ANSYS Fluent - CFD Final year thesis

Computational aerodynamic analysis of a
rear spoiler on a car in two dimensions
By
Dibyajyoti Laha
(Student No: 1227201)
Supervisor
Dr. Ahad Ramezanpour
A dissertation submitted in partial fulfilment for the degree
Of
Bachelor of Engineering Honours (Engineering: Mechanical)
In
Mechanical Engineering
Faculty of Science & Technology

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ACKNOWLEDGMENT
This research paper is a report of “Aerodynamics of a rear spoiler on a car in 2D using CFD
software to analyse the results”. It was only possible through the help of the course moderators including:
Lecturers, industrial CFD consultants, and in essence, all sentient beings. On the same occasion, please allow
me to dedicate my acknowledgment of gratitude towards the following significant lectures and contributors
for the research project.
First and foremost, I would like to show my gratitude and thanks to Dr. Ahad Ramezanpour for his
dedication to teach the every bits and parts of the thermodynamics and ANSYS Fluent which have been a
major use in the research project and devoting his invaluable time along with advice to hold a grip on the
report writing. He spent his class lectures to find the best possible solutions to the problems generated while
studying and helping to improve the standard of the brainstorming the solutions for the report. Not only being
a professor, he has been a great mentor & supervisor for the project with priceless feedback.
Secondly I would like to thank Dr. Habtom Mebrahtu in advising to write a research report referring IET
publications as my personal tutor at Anglia Ruskin University, Anglia Ruskin University for providing the
infrastructure and the ANSYS Laboratory for conducting the research. I would also like to extend my
gratitude to my colleague Miss Ambika Samanta for assisting and explaining the research survey, software
at times when needed.
Alongside my parents, my father Mr. Dilip Kumar Laha, Deputy Site Manager, Jacobs Engineering India
Pvt. Ltd, a Jacobs Engineering for briefing me and making me understand the investment of potential in the
world of designing and Finite Element Analysis in industrial background and my mother Mrs. Chaitali Laha
for boosting my enthusiasm while studying abroad while also funding me financially for the project.

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DECLARATION BY THE AUTHOR
I hereby declare that the work in this report is my own except for quotations and summaries which have been
duly acknowledged by in citation references. I have clearly stated the contribution of others to the production
of this work as a whole. I have read, understood and complied with the Anglia Ruskin University academic
regulations regarding the assessment offences, including but not limited to plagiarism.
I have not used material contained in this work in any other submission for an academic award or part thereof.
I acknowledge and agree that this work may be retained by Anglia Ruskin Ruskin University and made
available to others for research and study in either an electronic format or paper format or both of these and
also may be available for library or inter-library loan. This is on the understanding that no quotation from this
work may be made without proper acknowledgment.
Candidate Signature: ……………………………………………………..
Candidate Student Number: ……………………………………………….
Date: ………………………………………………………………………..

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Table of Contents
Table of Figures................................................................................................................................................... 8
List of Tables:................................................................................................................................................ 11
ABSTRACT ..................................................................................................................................................... 12
NOMENCLATURE:............................................................................................................................... 13
Terms used: ....................................................................................................................................... 13
Variables relating to CFD results: ..................................................................................................... 13
CHAPTER - 1 ................................................................................................................................................... 14
INTRODUCTION......................................................................................................................................... 14
1.1 PROJECT INTRODUCTION.................................................................................................... 15
1.2 PROBLEM BACKGROUND..................................................................................................... 16
1.3 PROJECT AIM & OBJECTIVE............................................................................................... 17
1.4 DISSERTATION DESCRIPTION ............................................................................................ 17
1.5 PROJECT SURVEY & OBSERVATION ................................................................................ 18
1.6 PROJECT LIMITATION .......................................................................................................... 19
CHAPTER 2...................................................................................................................................................... 20
LITERATURE REVIEW & THEORITICAL BACKGROUND ................................................................ 20
2.1 LITERATURE REVIEW........................................................................................................... 21
2.2 GENERAL CONCEPTS............................................................................................................. 24
2.2.1 LIFT CONCEPT ................................................................................................................... 24
2.2.2 DRAG CONCEPT................................................................................................................. 25
2.2.3 BERNOULLI’S EQUATION ............................................................................................... 26
Application in the research model:.................................................................................................. 27
2.3 AERODYNAMIC FORCES....................................................................................................... 28
2.3.1 DRAG FORCE...................................................................................................................... 28
2.2.2 LIFT FORCE......................................................................................................................... 28
2.3.3 DOWNFORCE...................................................................................................................... 29
2.4 AERODYNAMIC PRESSURE DISTRIBUTION.................................................................... 30
Application in the research work:...................................................................................................... 34
2.5 RELATION BETWEEN COFFICIENTS OF DRAG & LIFT............................................... 34
2.6 AERODYNAMIC PRODUCT - REAR SPOILERS................................................................ 34
2.6.1 HEIGHT OF REAR SPOLIERS ........................................................................................... 35

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2.7 CONTINUTY EQUATION........................................................................................................ 37
Application in the research:............................................................................................................... 38
2.8 NAVIER STOKES EQUATION................................................................................................ 38
2.9 DIMENSIONAL ANALYSIS & SIMILITUDE ....................................................................... 40
CHAPTER 3...................................................................................................................................................... 41
METHODOLOGY........................................................................................................................................ 41
3.1 INTRODUCTION ...................................................................................................................... 42
3.1.1 QUALITATIVE VS. QUANTITATIVE: QUESTIONS & APPROACH............................ 42
 Qualitative Methods: ..................................................................................................................... 42
Coherence of qualitative method in the research work: .................................................................... 42
 Quantitative Methods: ................................................................................................................... 43
Coherence of qualitative method in the research work: .................................................................... 43
3.2 ENGINEERING DETERMINING METHODS ..................................................................... 44
3.2.1 EXPERIMENTAL METHOD: ............................................................................................. 44
3.2.2 ANALYTICAL METHOD: .................................................................................................. 45
3.2.3 NUMERICAL METHOD: .................................................................................................... 45
1. Finite Difference Method: ......................................................................................................... 45
2. Finite Element Method:............................................................................................................. 46
3. Finite Volume Method: ............................................................................................................. 46
3.3 COMPUTATIONAL FLUID DYNAMICS ............................................................................. 47
3.3.1 INTRODUCTION TO CFD.................................................................................................. 47
3.3.2 HOW DOES CFD MAKE PREDICTIONS?........................................................................ 47
3.3.3 CFD ANALYSIS PROCESS ................................................................................................ 48
3.3.4 MESHING............................................................................................................................. 49
1. Structured mesh generation:.............................................................................................................. 49
a. Algebraic grid generation: ............................................................................................................. 50
b. PDE Mesh generation:................................................................................................................... 50
2. Unstructured mesh generation:...................................................................................................... 51
3.3.5 MESH QUALITY ................................................................................................................. 53
1. Mesh Element Distribution:.......................................................................................................... 53
2. Cell Quality: ................................................................................................................................. 54
3.3.6 BOUNDARY CONDITIONS ............................................................................................... 54

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Inlet & Outlet Boundary:................................................................................................................... 54
3.3.7 COMPUTING SETUP .......................................................................................................... 55
3.3.8 CONVERGENCE ................................................................................................................. 56
3.3.9 ERRORS................................................................................................................................ 56
Physical Errors: ................................................................................................................................. 56
Discretization Error: .......................................................................................................................... 57
Programming Errors:......................................................................................................................... 57
Computer-round off Errors:............................................................................................................... 57
Iterative Convergence Error: ............................................................................................................. 57
CHAPTER 4...................................................................................................................................................... 58
NUMERICAL SETUP.................................................................................................................................. 58
4.1 INTRODUCTION ....................................................................................................................... 59
4.2 DEVELOPING THE DIGITAL BASE LINE MODEL .......................................................... 60
4.2.1 GEOMETRY......................................................................................................................... 60
4.3 MODELING IN THE INVENTOR 2014...................................................................................... 61
4.4 DESIGNING THE BLM............................................................................................................... 61
Original Specifications:......................................................................................................................... 61
Inventor Steps:....................................................................................................................................... 62
Step 1: Initial Setup ........................................................................................................................... 62
Step 2: Selecting the design sketch.................................................................................................... 62
Step 3: Selecting the work plane ....................................................................................................... 63
Step 4: Importing Image based design .............................................................................................. 63
Step 5: Designing using points.......................................................................................................... 64
Step 6: Finalising the sketch and dimensioning ................................................................................ 64
Step 7: Creating the boundary walls.................................................................................................. 65
Step 8: Generating the Boundary surface.......................................................................................... 65
4.4.1. BLM PRESENTATION........................................................................................................ 67
4.5 MODEL WITH BUILT-IN SPOILER BY MANUFACTURER............................................ 68
4.6 MODEL WITH DECKLID SPOILER...................................................................................... 69
4.7 MODEL WITH OPEN TYPE SPOILER ................................................................................. 71
4.8 ANSYS WORKBENCH SETUP................................................................................................ 72
Step 1: Extracting the CAD file......................................................................................................... 72
Step 2: Updating the boundary condition for the FLUENT .............................................................. 73
Step 3: Setting the Meshing........................................................................................................... 76

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Step 4: FLUENT Setup................................................................................................................. 79
4.9 POST PROCESSING SET UP................................................................................................... 80
4.10 RESIDUALS & ERRORS ......................................................................................................... 86
CHAPTER 5...................................................................................................................................................... 87
ANSYS FLUENT RESULTS & ANALYSIS............................................................................................... 87
5.1 INTRODUCTION ....................................................................................................................... 88
5.2 ANALYSIS FOR BLM ............................................................................................................... 88
Velocity Contours:............................................................................................................................. 88
Pressure Contours:............................................................................................................................. 89
Static pressure.................................................................................................................................... 90
Turbulence Contours: ........................................................................................................................ 90
5.3 ANALYSIS FOR MANUFACTURER MODEL...................................................................... 91
5.4 ANALYSIS FOR DECK LID SPOILER .................................................................................. 96
5.5 ANALYSIS FOR OPEN STYLE SPOILER............................................................................. 99
Pressure Contours:........................................................................................................................... 100
Turbulence Contours: ...................................................................................................................... 101
5.6 VELOCITY MAGNITUDE COMPARISION TABLE: ....................................................... 102
5.7 PRESSURE COMPARISION:................................................................................................. 104
5.8 TURBULENCE COMPARISION........................................................................................... 107
5.9 RESULTANT FORCES............................................................................................................ 109
CHAPTER 6.................................................................................................................................................... 111
CONCLUSION & FUTURE SCOPE ......................................................................................................... 111
Conclusions ............................................................................................................................................ 112
Future Scope .......................................................................................................................................... 113
REFERENCES................................................................................................................................................ 114
APPENDICES................................................................................................................................................. 118
APPENDIX 1 ......................................................................................................................................... 118

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What Are the Navier-Stokes Equations?............................................................................................. 118
How Do They Apply to Simulation and Modeling?................................................................................ 118
Example: Laminar Flow Past a Backstep................................................................................................ 118
Different Flavours of the Navier-Stokes Equations................................................................................. 120
About the Reynolds and Mach Numbers............................................................................................. 120
Low Reynolds Number/Creeping Flow............................................................................................... 120
About the Experiment...................................................................................................................... 121
Modeling the Experiment................................................................................................................ 121
Flow Compressibility .......................................................................................................................... 123
Incompressible Flow ....................................................................................................................... 123
Compressible Flow.......................................................................................................................... 123
What Flow Regimes Cannot Be Solved by the Navier-Stokes Equations?............................................. 125
APPENDIX 2 ......................................................................................................................................... 127
RESEARCH PROPOSAL .................................................................................................................... 127
1. RESEARCH INTRODUCTION ................................................................................................. 127
2. RESEARCH AIM ................................................................................................................... 128
3. RESEARCH OBJECTIVE...................................................................................................... 128
4. RESEARCH LITERATURE REVIEW .................................................................................. 129
5. RESEARCH METHODOLOGY ............................................................................................ 130
PROJECT LIMITATIONS.......................................................................................................... 130
6. OBSERVATIONS & CALCULATIONS ............................................................................... 131
7. RESEARCH CONCLUSION.................................................................................................. 131
RESEARCH ETHICS APPLICATION FORM................................................................................. 132
CV, Cover Letter and Exit Plan........................................................................................................... 138

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Table of Figures
Figure 1 Showing spoiler at the back of a sedan car ......................................................................................... 15
Figure 2 Front Spoiler on Maserati ................................................................................................................... 15
Figure 3 Open type rear spoiler......................................................................................................................... 15
Figure 4 Flow of air around a car generating pressure areas & lift directions .................................................. 16
Figure 5 Built-in spoiler .................................................................................................................................... 18
Figure 6 Aftermarket deck lid spoiler................................................................................................................ 18
Figure 7 Different types of spoilers available in market. .................................................................................. 18
Figure 8 Wind tunnel test .................................................................................................................................. 20
Figure 9 Failed La Bomba car........................................................................................................................... 21
Figure 10 Dimitris first aerodynamic car design............................................................................................... 21
Figure 11 Water drop shape .............................................................................................................................. 21
Figure 12 Water drop shaped car Persu............................................................................................................. 21
Figure 13 Porsche 911 streamline car................................................................................................................ 22
Figure 14 Volkswagen Beetle ........................................................................................................................... 22
Figure 15 Coefficient of drag value of cars changing over decade ................................................................... 22
Figure 16 Opel's GT a failure model with spoiler ............................................................................................. 23
Figure 17 shows the direction of flow, Lift and drag ........................................................................................ 25
Figure 18 Flow of air/ fluid around a spherical body to demonstrate low and high pressure regions............... 26
Figure 19 a.) Left shows the low pressure. b) Values of coefficient of pressure around the geometry .......... 27
Figure 20 shows downforce generated due to spoiler. ...................................................................................... 29
Figure 21 shows airflow in profile for the Nissan R35 GTR ............................................................................ 30
Figure 22 shows region of high (blue) & low (yellow) pressure of a corvette Stingray ................................... 31
Figure 23 Pressure Coefficients Plotted Normal to surface............................................................................... 32
Figure 24 Region of high & low pressure around a car..................................................................................... 32
Figure 25 Variation of Cp along with the geometry.......................................................................................... 33
Figure 26 shows the region of high & low pressure along with the car geometry. ........................................... 33
Figure 27 Gillespie experiment of how height of spoiler affects the pressure. ................................................. 35
Figure 28 Variance of pressure coefficient along.............................................................................................. 35
Figure 29 Pressure coefficient along the front end and rear end with & without spoiler.................................. 36
Figure 30 shows values change when spoiler retracts and in action ................................................................. 36
Figure 31 shows different mounting of the rear spoilers affect the Lift and the Drag coffieicient value.......... 36
Figure 32 Body used to show equation of continuity........................................................................................ 37
Figure 33 showing the use of continuity in ANSYS Fluent.............................................................................. 38
Figure 34 Wind Tunnel test of spoiler on Porsche 911 Carrera ........................................................................ 41
Figure 35 Pie chart showing the three different methods of prediction ............................................................ 44
Figure 36 shows a fine structured mesh on a model.......................................................................................... 50
Figure 37 mapping of the physical coordinates on the x, y coordinates............................................................ 50
Figure 38 Generation of unstructured mesh of BMW 3 series model............................................................... 51
Figure 40 adjusting the element sizes and finding the number of elements...................................................... 52
Figure 39 Meshing of the model with minimum 2 & maximum 4 mm element size........................................ 52
Figure 41 meshing with default configurations................................................................................................. 53
Figure 42 meshing obtained adjusting sizing .................................................................................................... 53

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Figure 43 defining the boundary conditions on geometry in ANSYS............................................................... 55
Figure 44 obtaining convergence of the operating equations in ANSYS Fluent before post processing.......... 56
Figure 45 Top and bottom shows analysis of the models in the ANSYS.......................................................... 58
Figure 46 BMW 3 series dimensions ................................................................................................................ 61
Figure 47 Initial steps using inventor ................................................................................................................ 62
Figure 48 generating a 2D sketch on inventor................................................................................................... 62
Figure 49 creating a sketch................................................................................................................................ 63
Figure 50 using image pointing system to generate BMW 3 series model ....................................................... 63
Figure 51 importing the image .......................................................................................................................... 64
Figure 52 creating the constrained sketch ......................................................................................................... 64
Figure 53 creating the boundary walls for ANSYS........................................................................................... 65
Figure 54 creating the boundary patch for boundary walls............................................................................... 66
Figure 55 finishing the boundary patch............................................................................................................. 66
Figure 56 Deck-lid model spoiler...................................................................................................................... 70
Figure 57 ANSYS workbench........................................................................................................................... 72
Figure 58 generating the named boundaries...................................................................................................... 73
Figure 59 generating the named boundary and geometry condition in built-in the model................................ 74
Figure 61 generating the boundaries for Open Spoiler model........................................................................... 75
Figure 60 generating boundary conditions for deck-lid spoiler model.............................................................. 75
Figure 62 default mesh...................................................................................................................................... 76
Figure 63 adjusting the mesh to 1 mm minimum and 2 mm maximum............................................................ 76
Figure 64 Updated mesh of BLM...................................................................................................................... 77
Figure 65 updated mesh of built-in model spoiler............................................................................................. 77
Figure 66 updated mesh of deck-lid spoiler ...................................................................................................... 78
Figure 67 updated mesh for open spoiler .......................................................................................................... 78
Figure 68 Fluent setup....................................................................................................................................... 79
Figure 69 applying the general settings............................................................................................................. 80
Figure 70 changing the velocity formulation .................................................................................................... 81
Figure 71 adjusting the model settings.............................................................................................................. 82
Figure 72 adjusting the fluid selection .............................................................................................................. 82
Figure 73 assigning the input velocity (similar for all 4 cases)......................................................................... 83
Figure 74 selecting the initialization ................................................................................................................. 83
Figure 75 selecting number of iterations for accuracy ...................................................................................... 84
Figure 76 shows converging the equations........................................................................................................ 85
Figure 77 showing the converged equations ..................................................................................................... 85
Figure 78 Velocity magnitude picture from Fluent........................................................................................... 88
Figure 79 pressure contours............................................................................................................................... 89
Figure 80 shows static pressure graph............................................................................................................... 89
Figure 81 shows the stagnation point ................................................................................................................ 90
Figure 82 shows turbulence graph of the BMW Body and the tyres (in red).................................................... 90
Figure 83 Velocity in X axis ............................................................................................................................. 91
Figure 84 Velocity magnitude in manufacturer’s –built in model .................................................................... 91
Figure 85 shows velocity in Y direction............................................................................................................ 92
Figure 86 shows the pressure contours.............................................................................................................. 92
Figure 87 shows the static pressure graph......................................................................................................... 93

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Figure 88 shows same stagnation region as the base line model....................................................................... 93
Figure 89 shows the turbulence in case 2.......................................................................................................... 94
Figure 90 shows the kinetic energy of the turbulence region............................................................................ 95
Figure 91 shows velocity magnitude in deck-lid spoiler................................................................................... 96
Figure 92 shows velocity in x direction ............................................................................................................ 96
Figure 93 enlarged picture showing the lesser velocity around the model........................................................ 97
Figure 94 showing the pressure contours for deck-lid model............................................................................ 97
Figure 95 showing the static pressure region in graph ...................................................................................... 98
Figure 96 shows turbulence in the deck-lid spoiler car..................................................................................... 98
Figure 97 shows the velocity contours for open style spoiler model car........................................................... 99
Figure 98 shows the velocity in x direction....................................................................................................... 99
Figure 99 shows enlarged image of the velocity magnitude ........................................................................... 100
Figure 100 shows the pressure contours in open style spoiler model.............................................................. 100
Figure 101 shows the graph for the static pressure along with the geometry.................................................. 101
Figure 102 shows the turbulence contours for the open style spoiler model................................................... 101
Figure 103 shows the velocity magnitude. From top to bottom Case 1, 2, 3, 4 respectively......................... 102
Figure 104 shows the pressure contours for cases 1, 2, 3, 4 respectively........................................................ 104
Figure 105 shows the pressure graphs for cases 1, 2, 3, 4 respectively........................................................... 105
Figure 106 shows the turbulence regions in cases 1, 2, 3, 4 respectively........................................................ 107
Figure 107 shows region of wake turbulence.................................................................................................. 108
Figure 108 figure of a deck-lid spoiler at rear of BMW 3 series..................................................................... 111

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List of Tables:
Table 1 Upper body velocity magnitude for case 1, 2, 3, 4............................................................................. 103
Table 2 Lower body velocity magnitude for cases 1, 2, 3, 4........................................................................... 103
Table 3: Upper body pressure comparison for cases 1, 2, 3, 4....................................................................... 106
Table 4: Lower body pressure comparison for cases 1, 2, 3, 4........................................................................ 106
Table 5: Comparison table for turbulence in cases 1, 2, 3, 4........................................................................... 108
Table 6: Resultant forces on the model car body for cases 1, 2, 3, 4 .............................................................. 109
Table 7: Resultant forces from tyres for cases 1, 2, 3, 4.................................................................................. 109
Table 8: Total drag and lift forces in cases 1, 2, 3, 4....................................................................................... 110

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ABSTRACT
Performance, safety, manoeuvrability of a car depends on multi-disciplinary elements/ factors such as car
engine, tyres, aerodynamics, and ergonomics of design and most proficiently the driver. With the recent years,
inflation in the fuel prices & the demand to have reduced greenhouse emissions has played a significant role
in redefining the car aerodynamics. This concentrated on the utilization of negative lift called the down force
and resulting in several improvements. Aerodynamic drag created by the car results in the maximum fuel
consumption on highway, almost 50%. These aerodynamic properties are used to study the drag & stability of
car’s performance. Improvement in the aerodynamic drag can be achieved in multiple ways of introducing
active and passive air flow control. Rear spoilers are an example of the passive air flow control of the
aerodynamic drag. Generally rear spoilers are used to slower down the air flow and accumulate air which
helps increasing the pressure around the trunk and removing any chance of low pressure. The research
investigates on the effect of the rear spoiler in the aerodynamic drag, stability and efficiency. The research
focuses on 2D model of BMW 3 series sedan car with & without spoilers and the iterations of the rear spoilers
are designed in Auto desk inventor software. Modifications in the rear spoilers are done to obtain the minimal
drag and maximum downward force. The 2D surface model is extracted as CAD file with, without on the car
and individual rear spoilers are analysed on the CFD software ANSYS Fluent. The use of CFD software is to
calculate the estimated drag and lift values acting on the car as well as the drag force and the coefficient of lift
to improve the drag & stability. It involves understanding the basic applications of the post processing tools.
The results showed that the rear spoilers help in reducing drag by creating high pressure at the rear of the car.
Key Words: CFD, Fluent, Aerodynamics, Drag, Lift, Meshing, FVM, Inventor, Pressure, Velocity, Turbulence.

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NOMENCLATURE:
CD : Coefficient of drag
CL : Coefficient of Lift
CP : Coefficient of Pressure
P : Pressure
ρ : Density
v : Velocity
φ : Quantity
A : Area
m : Mass
𝛻 : Divergence
𝜕 : Partial Diffentiation
t : Time
ε : Epsilon
ω : Omega
Terms used:
CFD : Computational Fluid Dynamics
CAD : Computer Aided Engineering
BLM : Base Line Model
Free Stream : Stream line fluid flow
2D : Two dimensional object having length and breadth.
Variables relating to CFD results:
Drag Force : Component of force acting in the x direction
Lift Force : Component of force acting in the Y direction
Downforce : Negative of lift force.

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1.1 PROJECT INTRODUCTION
The 20th
century has seen some of the finest sedan cars. From highest speed Hennessey Venom GT
reaching up to 270.49 mph, Bugatti Veyron to the luxurious Rolls Royce phantom and much more. Personal
cars ranging from hatch backs, sedans & SUV have seen major changes in their design and ergonomics
depending on their customer’s choice. Aerodynamics for the cars has changed gradually from initial designers
to the manufacturers’ to obtain more power under the hood. This means more stability; better performance,
better grip and most prominently increase the comfort of the car. People seem to have sportier look to have the
best output performance. This certainly does mean that the cars are equipped with more additional parts such
as air dams, front and rear spoilers, and use of VGs (vortex generators) on the surface of the cars. Most widely
used are the rear spoilers in the passenger cars. This aids in greater drag reduction and in the same occasion
increases the stability of the car.
Mostly mounted on the car’s rear depending on the fixing location of the car rear (figure 1,3 ) either a
fastback, notch-back or square back. Spoilers can even be mounted in the front of the car as air dams with the
bumpers (figure 2). However rear spoilers provide the maximum contribution to the aerodynamic drag and
lift. This occurs as rear spoilers stagnant the flow of the air at the rear of the car generating a high pressure
region and reducing the low pressure. This directs the flow and offer greater drag reduction, increasing the
downward force at the rear and more stability.
Figure 1 Showing spoiler at the back of a sedan car
Figure 2 Front Spoiler on Maserati Figure 3 Open type rear spoiler

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1.2 PROBLEM BACKGROUND
Usually when a person drives the car, the car breaks through the barrier of the air. This creates a
region of high pressure as the air flows from the windscreen to the top surface of the car. Gradually there is a
region of the low pressure created at the rear of the car. In a worst case scenario, the air which possibly makes
way to the rear window creates a notch due to the window dropping down to the trunk, creates a region of
vacuum or low pressure which lifts the car and acts on the surface area of the trunk. This is possibly because
of the lack of the air being refilled in that region.
Technically a spoiler regulates the flow of air around the rear end by accumulating more air refill in
the region of the low pressure so that more high pressure region is created with better stability and the car
always sticks to the ground. Use of spoiler is quite unique and impressive as most of the sedan & hatch back
cars tends to become light at the rear end lifts the car while the spoilers help acting as an air barrier. This also
allows reducing the axle-lift and reduction of dirt in the rear surfaces of the car.
Figure 4 Flow of air around a car generating pressure areas & lift directions

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1.3 PROJECT AIM & OBJECTIVE
The research project aims to accumulate all possible information & Knowledge of a model car BMW
3 series sedan class aerodynamics focusing on the rear spoiler use. Aerodynamic forces can be used to
improve the tyre adhesive nature and find the vehicle performance. It describes the side slipping forces acting
on the tyre. Using three different types of the rear spoilers & their CFD analysis results to achieve the aim
using following objectives in the research project.
 Analysis of the air flow around the car without the rear spoiler,.
 Analysis of the air flow around the car with a concept rear spoiler.
 Effect of the aerodynamics on the car
 Analysis with the variation of the rear spoilers on the down force, drag and the stability of the car.
 Estimating the CD (Coefficient of Drift) & CL (Coefficient of Lift) on a high speed run of the car.
 Comparison of the CD and CL values with (variations in rear spoiler designs) and without rear spoilers.
 Analysis of all the models on the CFD software ANSYS Fluent.
 Drawing out the possible outcomes comparing the results & establishing the relation of using rear
spoilers for better performance, reduced lift and drag.
1.4 DISSERTATION DESCRIPTION
The dissertation report focuses on the investigation of the rear spoiler uses and its effect to the
aerodynamic drag, stability and lift as calculated by CD and CL. This obtained by a series of consecutive tests
and steps and research. The dissertation report starts with a literature review covering the basic standard
principles of aerodynamics which is easy to be understood by a layman. This is followed by theory which
focuses of the laws of physics and engineering of aerodynamics governing the equations and results. This also
includes the predominant theories and concepts used in the project.
As the title reflects Aerodynamics of a car using rear spoiler, a series of the CAD files are generated of the
different types of spoilers. This also includes the design of the model car with and without the rear spoiler
along with the spoilers. All the designs are generated on the Auto Desk Inventor 2014 as 2D surface. The
designs are exported as .iges or .step file to be extracted to the CFD package. ANSYS Fluent is used to run the
models for analysis. The CFD software interprets and results the value of CD & CL which is explained in the

18
observations & calculations. The obtained results are explained and plotted on a graph. Iteration of the
spoilers is compared to the base model.
Finally finishing the report with conclusion, future works are also included to underpin the potentials of the
further research that could be extended by potential candidates.
1.5 PROJECT SURVEY & OBSERVATION
According to a recent study (Stavros, 1995-2015) survey observation, a prominent feature was
observed that most of the passenger cars have started using spoilers with ranges from variation in their height.
Besides the research reports, surveys from different leading magazines like Car magazine UK, (Tim Pollard,
2015) and observing the inbuilt spoilers built by the car manufacturers were studied. It was found that there
were many different types of spoilers that could be used on the cars. Our study focuses on the fast sedan car
which has sufficient rear space to have the spoilers mounted on it. Since the fast sedan cars have rear boot
space called the notchback, spoilers like deck-lid and free standing spoilers can be used. This results in
eliminating the square hatchback car and hatchback spoilers. Most of the fast sedan car manufacturers provide
with deck-lid spoilers. This is usually done to minimize any errors during analysing.
Figure 6 Aftermarket deck lid spoilerFigure 5 Built-in spoiler
Figure 7 Different types of spoilers available in market.

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1.6 PROJECT LIMITATION
One of the major limitations of the project was the system requirements. Most of the designs were
generated and simulated on a 4 core processor computer with 4 GB of ram. This underscored and limited the
designs to be in 2D surface models. As making in 3D would consume more memory power and the lab was
equipped with only above specification computers. Using 2D geometry has a major drawback as a restriction
of boundary. Other major dependencies were the designs were generated on the Auto Desk inventor
professional 2014. The researcher has previous knowledge of using auto desk inventor instead of the
designing geometry in ANSYS Fluent. This consumed a major time as modifications and iterations based on
the basic model, the researcher had to refer back to the initial models in the CAD format in inventor.
Although the project started with a delay in analysis, much of the major time loss was a result of the
initial geometry design and using ANSYS Fluent.

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CHAPTER 2
LITERATURE REVIEW & THEORITICAL BACKGROUND
Figure 8 Wind tunnel test
Picture Courtesy: GTR Blog, 2015

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2.1 LITERATURE REVIEW
The purpose of this chapter is to have a generic view on the background of spoilers in the automobile
industry. The evolution of the spoilers from a mere product to a must need requirement in the modern period.
Alongside with the changes, it also describes the basic concepts and theories of aerodynamics that play a
crucial role in the research.
It all started in late 1890. The earliest design of a car based on the concepts of aerodynamics was made by
Camille Jenatzy, a Belgium race car driver (Dimitris, 2007). This was followed by a conceptual design by
Alfa Romeo in 1914. The car was “La Bomba” which was an aerodynamically designed but failed because of
world war era and its weird design (Altecc, 2001-2015)
After the post-world war era the concept of the aerodynamics on the cars were more focused. Number of
concept designs was analysed. This resulted in water dropped shaped cars as, water drops were considered to
be aerodynamically perfect (Patrascu, 2011).
Figure 11 Water drop shape
Figure 10 Dimitris first aerodynamic car design Figure 9 Failed La Bomba car.
Figure 12 Water drop shaped car Persu

22
In the same era, Germany played an active role in understanding the aerodynamics involved in a car. Infact
Germany was forbidden in building aircrafts after the war. This led the aerodyamic engineers to convert their
aero ideas into cars and make it an aeronautical flavored (World War planes, 2001).
Edmund Rumpler an Viennese pioneer in aerodynamics in cars tested the first car in wind tunnel. The car he
tested was Trophenwagen which showed a drag of about 1/3rd
of the contenporary vechiles. In the same
period Paul Jaray, an Austo-Hungarian designer well know for his aerodynamic and streamline design of cars.
He innovated the smooth surfaces of the body of the car, headlamps and cambered windsheilds. Much of his
work were copied or adopted in big car manufacturing players like BMW, Mercedes, Audi, Diamler-Benz
(Dimitris, 2007). However the streamline shaped cars were never a hit since they generated a high drag
cofficient of around 0.4. Some of the streamline designs still in use are like Porsche 911, Vokswagen Beetle.
In early 1970’s the crisis for petrol and more efficiency resulted in Kammback cars. Wunibald Kamm an aero-
dynamist from Germany brought the concept of aerodynamics in cars, which was the use of air foils. He
showed that the air foils with slight truncated tailing edge have slightly lesser drag coefficient compared to
completely air foil shaped cars. The post-world war 2 era saw a drastic change in the automobile shapes from
brick designs to rain drop and streamline shapes.
Figure 14 Volkswagen BeetleFigure 13 Porsche 911 streamline car
Figure 15 Coefficient of drag value of cars
changing over decade

23
All these changes in the car designs were the result of the detailed optimization of the drag improvement in
1970s. It was based on the numerous minor and major modifications in the drag reductions. Detail
optimization included the modifications in curvatures, pillars, location of spoilers and much more but reached
it limits quiet early. Some of the failure example was Opel’s GT which had a drag coefficient of 0.42 even
with streamline design and spoiler.
Figure 16 Opel's GT a failure model with spoiler
Even yet the detail optimization resulted in the dramatic change but the prior concentration of the car
manufacturers was in the reduction of the drag. By this time, shape optimization was given more priority. Re-
evaluation of work by the aero dynamists from early 1930s was conducted. This led to a realistic car design
and shape with lower drag coefficient. Audi 100 was the first manufactured which a drag coefficient of 0.3
(Edgar, 2006).
Current State of Art
 The current state of art in aerodynamics utilizes both the detail and the shape optimization.
 The reasonable drag coefficient can vary from 0.25 to 0.35 for modern cars.
 For future aspects and reasonable target a drag coefficient of 0.25 is idealistic.
The evolution of the car spoilers involved use of general concepts & theories of physics. These were flow of
air around the streamlined body, effect of the pressure, way the air as a fluid acts when the car is in motion
and much more. It is hence very important to discuss them in brief to get a clearer view of the working science
behind the aerodynamic product spoiler and the car. From the aircrafts to the cars, the aerodynamicists have
invested a mixture of aeronautics in cars that has resulted in more efficient models. Much of the credit in the

24
research work of the evolution is involved in experimental coherence with the laws of physics and
computational analysis.
2.2 GENERAL CONCEPTS
To provide a clear view to the literature review, the whole literature review has been sub categorized
into different parts. Each part defines & makes the concepts of the theory easier to be understood.
2.2.1 LIFT CONCEPT
In aerodynamics lift (figure 17) is a force that holds an object in the air. In automobiles the pressure
difference of the high pressured frontal end to the low pressure rear end generates the lift.
But how actually it is generated with velocity?
The answer lies in simple physics. Whenever air flows over an object or vice versa, the molecules of the gas
move freely. According to David Bernoulli (Bernoulli’s concept explained: 2.1.*) the pressure is directly
proportional and relates to the local velocity of the air (NASA, 2013). This explains why velocity varies and
pressure too. Lift is always perpendicular to the flow of the air on the automobiles. It is explained by the
following equation in aerodynamics:
𝑳 𝑫 =
𝟏
𝟐
𝛒𝐯 𝟐
𝑪𝒍 𝑨 Equation 1
Where 𝑳 𝑫 is the Lift force
𝛒 is the density of the fluid.
v speed of the object
CL is the lift Coffieicient
A is the cross sectional area.
This equation will be used further in the chapter of results to find the lift force obtained in the car body.
Generally the lift force will be the total force of the forces in y direction in addition to the viscous forces in the
y direction.

25
2.2.2 DRAG CONCEPT
Drag in general physics is referred or defined as the resistive force experienced by an object/ body
when it is in motion with respect to the fluid surrounding it. Drag forces are dependent on the velocity of the
object and is shown by a formula defined as:
𝑭 𝑫 =
𝟏
𝟐
𝛒𝐯 𝟐
𝑪 𝑫 𝑨 Equation 2
Where FD is the drag force
𝛒 is the density of the fluid
v is the speed of the object in the fluid
CD is the drag Coffieicient
A is the cross sectional area
Drag force is highly dependent on the density of the fluid, velocity of the object and cross sectional area of the
body acting with the fluid. This means the sleeker the body is less the drag coefficient (which is a
dimensionless value) less is the drag force is. However the velocity and density is also proportional to the drag
force. This will be used to calculate the net force acting on the x direction on the car body along with the
viscous forces.
Figure 17 shows the direction of flow, Lift and drag

26
2.2.3 BERNOULLI’S EQUATION
𝐏 +
𝟏
𝟐
𝛒𝐯 𝟐
+ 𝛒𝐠𝐡 = 𝐂𝐨𝐧𝐬𝐭𝐚𝐧𝐭 Equation 3
The Swiss mathematician & physicist (1700 – 1782) put forward a principle called Bernoulli’s equation (Eqn
3) which held for fluids in ideal state; pressure and density are inversely related: in other terms slowing
moving fluids exert more pressure than fast moving fluids. This equation is the fundamentals of the study of
the airflow around vehicles.
Bernoulli’s equation obtained by integrating Newton’s law F = ma (Munson, Young, and Okishi.
2006) is supported with the following assumptions:
 Air density does not change with the pressure.
 Viscous flow of the fluid is neglected.
 Steady state flow is assumed and always maintained.
 The fluid flow is compressible.
 The formula can be applied at any point in the streamline flow.
This resulted in the formula being derived to
𝐏 +
𝟏
𝟐
𝛒𝐯 𝟐 + γz = Constant Equation 4 (Munson 2006)
Or can be written as
𝐏
𝛒
+
𝟏
𝟐
𝐯 𝟐
= 𝒌 Equation 5 (Katz 1995)
The above equation is valid when height is not accountable.
Region of Low pressure Region of high pressure.
Figure 18 Flow of air/ fluid around a spherical body to demonstrate low and high pressure regions

27
Whenever the air flows over the body, it generates a velocity distribution resulting in the aerodynamic loads
acting on the body of the vehicle. The first is the shear force acting tangentially on the surface of the vehicle
body generating the drag force which is because of the viscous boundary layer. The second force is the
pressure force. The pressure force acts perpendicular to the surface of the body and has a contribution to both
drag and lift. Technically the vehicle’s downforce is the added effect of the pressure distribution (Katz, 1995)
Application in the research model:
As the model car/ car pass through a region of fluid, velocity changes with the geometry. This means the
geometry will have regions of high velocity and low pressure or vice versa. This is established by the equation
3, that when pressure is maximum, the velocity is zero as they equate to constant and vice versa.
Figure 19 a.) Left shows the low pressure. b) Values of coefficient of pressure around the geometry

28
2.3 AERODYNAMIC FORCES
2.3.1 DRAG FORCE
As already explained in 2.2.2 drag force opposes the motion of the car which is travelling. This
ultimately affects performance of the car, fuel economy as well as greater power is required to overcome the
force. As usually given by the expression in which is
𝑭 𝑫 =
𝟏
𝟐
𝛒𝐯 𝟐 𝑪 𝑫 𝑨
A: “A” is the frontal area in square of meter (m2
). The size of vehicle is directly related to the drag properties
and is characterised by the value of CDA. However the frontal area is slightly less than the total width &
length of the car measured in (m2
)
CD: Coefficient of Drag is a function of Shape, Reynold number (Re), Mach number (Ma), Froude number
(Fr) and relative roughness ε/l and is given mathematically by:
CD = Ø (Re, Ma, Fr, ε/l) (Munson, 2006)
The density of the air ρ is dependent on the temperature, humidity, altitude and pressure. On in any standard
condition the density of the air is 1.23 kg/m3
. Any change in the pressure is denoted by PX and temperature by
TX using the equation to find the density ρ (Gillespie, 1995).
𝛒 = 𝟏. 𝟐𝟐𝟓 [(
𝑷 𝑿
𝟏𝟎𝟏.𝟑𝟐𝟓
) (
𝟐𝟖𝟖.𝟏𝟔
𝟐𝟕𝟑.𝟏𝟔+𝑻𝒙
)]
In the eqn [ ] the term
1
2
ρv2
is the dynamic pressure of the air and v is the final velocity of the car.
2.2.2 LIFT FORCE
With the Drag force there is one more component of the force called the Lift force which tends lift the
car and reduces the friction between the tyres and the road. This means the force acts as the stability of the car
and handling too. Given by the eqn 1, i.e. 𝑳 =
𝟏
𝟐
𝛒𝐯 𝟐 𝑪 𝑳 𝑨 , lift force plays a significant role in the
aerodynamic optimization of the car.

29
The lift force is a dependent on the shape of the car. In the present modern day passenger cars, the coefficient
of lift ranges from 0.3 – 0.5 for any wind angle at zero degrees (Huco, 1998). However in crosswind
conditions the value of CL can vary from 1 and increases on.
This clears that even L is a function of geometry i.e. Ø (geometry).
2.3.3 DOWNFORCE
The force that is exerted on to the car by the aerodynamic properties of the rear spoiler is called the
downforce. This actually follows Newton’s third law. Every action has equal and opposite reaction. Hence the
downforce is the opposite force to the lift and is usually greater. The downforce is responsible for the car to
keep on to the track and provide more traction to the wheels.
Downforce is usually generated when air mover through and over the parts of the car (Fig ). This occurs when
the wing pans are set at angle which forces the air up and through it naturally generating a force downwards –
or the opposite force. The positive aspect of having a downforce is that since it adds traction to the wheel, it
also adds more stability to the car.
The down force can be given by the formula (T. Glossop, S. Jinks, R. Hopton, 2011):
𝑭 𝒘𝒊𝒏𝒈 =
𝟏
𝟐
(𝑾𝑯𝑨𝒐𝑨)(𝑪 𝑫 𝝆𝒗 𝟐
) Equation 6
Figure 20 shows downforce generated due to spoiler.

30
Where Fwing is downforce per wing
W is the wing span
H is the height of the spoiler.
AoA is the angle of attack.
CD is the coefficient of drag
𝝆 Is the density
𝒗 𝟐
Is the velocity, squared.
However the equation can be simplified as ß the effective area of each wing.
𝟏
𝟐
(𝑨𝒐𝑨)(𝑪 𝑫 𝝆𝒗 𝟐
)ß Equation 7
With the number of the spoilers (front & rear usually ranging from 3 to 5 this equation changes to
𝟏
𝟐
(𝑨𝒐𝑨)(𝑪 𝑫 𝝆𝒗 𝟐
)(ß 𝟏 + ß 𝟐 + ß 𝒏) Equation 8
2.4 AERODYNAMIC PRESSURE DISTRIBUTION
As the car moves through an ambient mass of air, the body of the car displaces bundle of imaginary
streamline filaments that constituent of the airflow field. Now as the stream line is displaced these streamlines
are made to accelerate from rest up to a velocity. This creates a pressure distribution across the air field and
the boundary of the body of the car (fig 22 ). The high static pressure also referred as the zero velocity is
Figure 21 shows airflow in profile for the Nissan R35 GTR

31
generally the stagnation point in the front of the car while the low static pressure area is the wind screen
header and the top roof peak of the car. (John D. Smidth, 2014)
The coefficient of pressure at any point on the surface of the car is characterised by the following equation
given by: 𝑪 𝒑 =
(𝐩−𝐩 𝟎)
(
𝟏
𝟐
𝝆 𝒗 𝟐)
[Eqn ] where Cp is the coefficient of pressure, p is the static pressure at the
vehicle surface, p0 is the free stream static pressure and rest of the variables are defined earlier.
Usually the value of Cp at the stagnation point is 1 & zero when the local as well as free static pressure is
same all over the flat section of the car body. The negative pressure coefficients can be obtained in certain
cases when the local velocities are greater than the free stream velocities.
The coefficient of the pressure depends upon the geometry of the car, hence is a function of the shape. The
distribution of pressure on most of the surface of the car is done by using Bernoulli’s equation [Eq. ]. The net
upward force is calculated by the integration of the total pressure distribution. The force obtained (Which is
usually negative) means that there is no requirement to enhance the stability of the car. The exact opposite
reactive force is the downforce (explained in 2.2.3) (Duysinx, 2014-2015)
Certain experiments on the pressure distribution calculated by different car manufactures and individual
research analyses are shown below. This will help to generate a clear concept of the pressure distribution
around a car.
Region of stagnation
Region of low pressure Corvette
Stingray.
Figure 22 shows region of high (blue) & low (yellow) pressure of a corvette Stingray

32
Figure 23 Pressure Coefficients Plotted Normal to surface
Figure 24 Region of high & low pressure around a car

33
Figure 25 Variation of Cp along with the geometry
Figure 26 shows the region of high & low pressure along with the car geometry.

34
Application in the research work:
We will further use this to find the coefficient of pressure in different models of the BMW 3 series model car.
The use of the pressure distribution will be important to understand the region of the high concentration of
pressure and low concentration along the geometry of the model car. Apart from the pressure distribution, this
topic will help in establishing the concept of topic 2.2.3.
2.5 RELATION BETWEEN COFFICIENTS OF DRAG & LIFT
Before we study and the application of the coefficient
From an experimental study of a generic car, it was concluded that the coefficients of drag and lift for the flow
around the body of the car is predominantly dependent on the slant angle. It was observed with the generic
model that from 0o
to 29o
the growth of the lift is linear and drastically changes to negative when the angle
reaches 30o
. The drag coefficient is minimum at angle of 15o
which means the lift coefficient is close to zero
and becomes 50% greater when the slant angle reaches 29o
.
However beyond the slant angle of 30o
the lift and drag becomes nearly constant. (Ivan Dobrev, Fawaz
Massouh, 2014).
Coefficient of Drag is given by: CD =
𝑭 𝒅
(
𝟏
𝟐
𝛒𝐯 𝟐 𝑨)
⁄ Equation 9
Coefficient of Lift is given by: CL=
𝑭 𝑳
(
𝟏
𝟐
𝛒𝐯 𝟐 𝑨)
⁄ Equation 10
Both CD and CL are dimensionless values.
2.6 AERODYNAMIC PRODUCT - REAR SPOILERS
The aerodynamic product spoilers are devices that increase the stability of the car, reduce the drag and
regulate the pressure difference resulting in the better performance of the car. The spoilers constitute of the
front and the rear spoilers. However the rear spoilers contribute to a major aerodynamic stability of the car
(Xu-xia Hu, 2011). The aerodynamic devices – rear spoilers acts as a diffuser. Usually mounted on the top
surface of the rear trunk to create/ generate pressure difference (explained in 2.3). Rear spoilers provide the
following advantages.

35
 Increases the tires capability to produce the required forces.
 Offering stability at a very high speed.
 Better traction generating fuel efficiency
 Improves braking performance.
2.6.1 HEIGHT OF REAR SPOLIERS
The way in which drag and lift happened is depend on the height of the spoiler. The influence on the
pressure distribution is shown below. The possibility of reducing drag is comparatively low. In fact on sporty
cars, and even more so on racing cars, even an increase in drag is accepted in order to ensure that the rear-axle
lift gets low.
Figure 28 Variance of pressure coefficient along
a.) angle of application b) with spoiler height
Figure 27 Gillespie experiment of how height of spoiler affects the pressure.

36
The extended rear spoiler can increase the pressure on hatch; as a result, rear axle lift is reduced about a third.
Figure shows how a rear spoiler influences in reducing lift force at rear. The spoiler causes a clear rise in
pressure on the rear slope in front of it. If the pressure is plotted versus the vehicle’s z/h for the centre
cross section, the reduction in drag is obvious
Figure 29 Pressure coefficient along the front end and
rear end with & without spoiler
Figure 31 shows different mounting of the rear spoilers
affect the Lift and the Drag coffieicient value
Figure 30 shows values change when spoiler
retracts and in action

37
The relation between the spoiler height, lift and drag follows a linear predictable trend obtained from a
research work on BMW sport 6 series at Johannesburg (Aberu, 2013). Increasing the spoiler height further
slows down the flow field passing over the roof line reducing the dynamic pressure drop to decrease the total
lift.
2.7 CONTINUTY EQUATION
According to the law of conservation, it can be stated that the mass can neither be created nor be destroyed.
This law can be used in the steady flow process which means that there is no change in the flow rate with time
through a control volume when the stored mass of the control does not change. (Engineering Tool, 2014)
 This means inflow is equal to the outflow.
The equation for the continuity equation can be shown as:
m = ρi1 vi1 Ai1 + ρi2 vi2 Ai2 + ρin vin Aim
= ρo1 vo1 Ao1 + ρo2 vo2 Ao2 + ρom vom Aom
Equation 11
Where:
m = mass flow rate (kg/s)
ρ = density (kg/m3
)
v = speed (m/s)
A = area (m2
)
With uniform density equation (1) can be modified to
q = vi1 Ai1 + vi2 Ai2 +vin Aim
= vo1 Ao1 + vo2 Ao2 + vom Aom (2)
Where:
q = flow rate (m3
/s)
ρi1 = ρi2 = ρin = ρo1 = ρo2 = ρom
Figure 32 Body used to show equation of continuity

38
Application in the research:
For all flows, FLUENT solves conservation equations for mass and momentum. For flows involving heat
transfer or compressibility, an additional equation for energy conservation is solved. For flows involving
species mixing or reactions, a species conservation equation is solved or, if the non-premixed combustion
model is used, conservation equations for the mixture fraction and its variance are solved. Additional transport
equations are also solved when the flow is turbulent (figure 33).
Figure 33 showing the use of continuity in ANSYS Fluent
Now since we will use the model of an original car, we will obtain the results for the model. To compare the
model with the original car, the easiest and the fastest way is dimensionally analyse the model and the car.
This will help in obtaining the values for the original car. Let’s discuss dimensional analysis and similitude in
brief.
2.8 NAVIER STOKES EQUATION
The Navier Stokes equation provides the foundation for fluids in motion. It is one more important
topic along with equation of continuity. It is important to discuss Navier Stokes equation as it forms the base
of the analysis if the fluid flows in CFD. Fluid has no limits for distortion when forces are applied. This means
that the fluid goes through number of forces. To simplify Navier derived an equation for the viscous fluid
Stokes slightly modified the equation to form a basic equation called Navier-Stokes equation:

39
The easy way to remember Navier Stokes equation is by understanding the concept1
. The whole process is
categorised into following three sections:
Transient
Convection
Diffusion.
Transient: It refers to the rate of change of the quantity in an infinite volume for a temporary time. Assuming
φ is any random physical quantity like mass, pressure, density, temperature or any other factor. Hence
mathematically transient process can be defined as
𝜕 𝜌φ
𝜕𝑡
Convection: If there is any presence of the velocity within the field, the quantity is transported. This is
defined as the convection method and is the first derivative multiplied by the velocity. Mathematically
represented as
𝛻. ( 𝝆𝒖 𝛗)
Diffusion: It refers to the transport of the quantity due to the presence of gradients of that quantity. It is
referred in the mathematical terms as
𝛻. λ𝛻𝛗
Where λ refers to the diffusion constant. This is equal to the thermal conductivity in the heat transfer.
Finally all the three equations are combined to obtain an accumulated equation referred to general transport
equation shown as
. Transient + Convection = Diffusion + Source
𝜕 𝜌φ
𝜕𝑡
+ 𝛻. ( 𝝆𝒖 𝛗) = 𝛻. λ𝛻𝛗 + 𝑆𝑜𝑢𝑟𝑐𝑒 𝛗
When obtaining the equation of continuity it can be said that 𝛗 is 1 (for compressible flows). When the
diffusion is not present and absence of the source all the terms can be set to 0.
𝜕 𝜌
𝜕𝑡
+ 𝛻. ( 𝝆𝒖) = 0
To obtain the Navier Stokes equation the physical factor φ can be replaced by the velocity component at the
time t. This represents the Navier Stokes equation as:
1
Shown in Patankar’s brief for understanding Navier Stokes Equation.

40
𝜕 𝜌 𝑢
𝜕𝑡
+ 𝛻. ( 𝝆𝒖 𝑢) = 𝛻. 𝜇𝛻𝑢 −
𝜕 𝜌
𝜕𝑥
+ 𝜌𝑔 𝑥 Equation 12
Similarly in the equation if u is replaced by v and w for y and z coordinates’.
In the ANSYS Fluent, the software that will be used to analyse the results in CFD, uses Navier Stokes
equations in the final volume discretization method. This equation provides a filtering operation. Mainly used
in the mesh grid sizing and grid spacing. This largely affects the mesh quality too. The background of the
meshing runs the Navier Stokes equations as in form of Fourier series to obtain a high quality mesh.
The literature review focused on the background history of the research product – spoilers along with the basic
laws & concepts of physics and aerodynamics acting on the product. This helped to give a depth idea of the
mechanism of the spoiler and how these laws still govern the digital analysis for the product.
The next chapter introduces and familiarizes with the use of different methods for comparative analysis and
introduces CFD.
2.9 DIMENSIONAL ANALYSIS & SIMILITUDE
Generally very few real flows can be solved by analytical methods. It requires huge laboratories and
more consumption of energy to run a wind tunnel as for example in this research project. Generating huge
forces in the wind tunnel can alone consume electricity of an entire village. As a result alternately, models of
the prototypes are generated and tested. This means the models and the prototypes need to match certain
criteria which are geometrical similarity and kinematic similarity. Satisfying the above mentioned criteria
results in dynamic similarity which means the results of the model can be equated to the prototype to find the
results of the forces in the prototype.
In the research results we will try to dimensionally analyse and similitude the actual value of the force in the
car from the obtained values of the model. There will be a limitation since, the model being used in the
research work is 2D has limitation on the results as they would have absence of forces in z coordinates.

41
CHAPTER 3
METHODOLOGY
Figure 34 Wind Tunnel test of spoiler on Porsche 911 Carrera
Picture Courtesy: website Pressebox.

42
3.1 INTRODUCTION
The research focuses on the application of the rear spoilers on the personal cars. Hence it was
important to discuss the vital aspects of the aerodynamics involved in the car and the effect of the spoilers on
the aerodynamics of the car in the literature review. The research work is meant to be aerodynamics of a rear
spoiler on a car in two dimension using Computational Fluid Dynamics software to analyse the results.
Throughout the research work there will be application of two approaches to compare and illustrate the
results. It is important to have an appropriate methodology of both qualitative and quantitative methodology to
obtain the final result.
3.1.1 QUALITATIVE VS. QUANTITATIVE: QUESTIONS & APPROACH
When compared to both qualitative and quantitative research work both methodology enquires &
implements statements of philosophy, enquiring strategies, surveying to collect the data, analysing and
interpreting the results. Qualitative approach emphasises on the essence and the ambience of the entities of the
research work. Putting the statement in other way means that qualitative approach focuses on the quality,
intensity of the matter, and amount that cannot be experimentally determined. This means that the
concentration is led on to the concepts, theories, metaphors, symbols and description. The research statement
often stressed on how socio – economic experience is obtained by giving a meaningful name to the research
work. The quantitative methodology on the other hand focuses on the analytical approach, statistics and data,
use of the numerical methods to interpret the research and approach the results with validation. This includes
the use of different numerical software to calculate the values and document the research work for future use.
 Qualitative Methods:
Quantitative method is the narrative way to explain the research work. This includes the theories, concepts
implications in everyday applications, decontructivism, phenomenon, past research, industry practice,
standards, implications, explore processes, the cultural studies, market research, products descriptions and
implementations. The researcher focuses on the best methods to draw the results for the research work.
Coherence of qualitative method in the research work:
The research work on aerodynamics of a rear spoiler on a car in two dimension using Computational Fluid
Dynamics software to analyse the results has explained the main qualitative methods. The entire research
work focuses on the use of the spoiler by the automotive industry from market point of research to the

43
factual reasons of using the product. Chapter 1 introduces the research project, and supports the socio
economic need for the product in the modern automotive industry, ways to design and analyse the product
as well as the project limitation. This is followed by Chapter 2, which emphasizes on the history of the
spoiler to evolution and practical implementation as a literature review & the general concepts and
theories of fluid dynamics working behind the product. The method of qualitative analysis is not only
restricted to the first two chapters instead it follows with the market survey and data collection of
applications of most used spoiler in industry and after market in chapter 3 as well as comparing the
obtained results with the quantitative methods.
 Quantitative Methods:
The quantitative method is more independent of the qualitative method. This implies that the researcher
has greater influence on the qualitative method. Quantitative method focuses on the application of
techniques to solve the problem statement of the project, conducting the research with different software
tools, illustrating the results, documenting the results, comparing with the historiography and stating the
conclusions.
Coherence of qualitative method in the research work:
The research uses more quantitative method to find the solutions. This focuses on the use of designing
software for the BLM and spoiler designs, using different methods of flow simulation, explaining the use
of ANSYS Fluent, comparing the methods of numerical flow analysis, importance of meshing and
selection the method, validating the simulation results and comparing it with the qualitative methods.
Each method has advantages and limitations depending on the level of illustration, opportunity to review the
collection process, proximity to obtained values and amount of biased based on the researcher.
The next topic discuses on the CFD in general.

44
3.2 ENGINEERING DETERMINING METHODS
Engineers have always been interested in understanding and predicting the behaviour of fluid flow
system behaviour & variables. There are three way of predicting methods which are included below:
Figure 35 Pie chart showing the three different methods of prediction
3.2.1 EXPERIMENTAL METHOD:
The most reliable and easiest way to predict the natural phenomenon is usually done by gathering the
information about the measurements. This is the common way of gathering the information of the full scale
equipment and predicts how the equipment would behave in real life application.
Pros:
 The actual model can be used for the experimental analysis for prediction.
 Accurate results can be used to understand the phenomenon
 This method plays an important role in deriving the statistics and data for future use.
Cons:
 Sometimes the actual equipment costs too much. This can be expensive method to apply in large
applications like in aeronautics or automobile industry.
Experimen
tal Method
Analytical /
Mathametical
Methods
Numerical
Methods

45
 This method of using actually collecting the information can result time loss as rigorous experiments
needs to be conducted to find the minute changes.
Application: In small scale product development, in using the past data for future design and development.
Examples include: Aeroplanes.
3.2.2 ANALYTICAL METHOD:
This method works on the consequences of the mathematical model. These mathematical models
describe the behaviour of the system. Usually the mathematical model is a set of differential equations which
are used to solve the problem.
Pros:
 Use of pre-set/ pre-defined differential equations
 These methods help engineers’ fundamentals of controlling and behaviour of engineering systems.
Cons:
 Limitations of validity of the solutions if too many assumptions and simplifications are made.
3.2.3 NUMERICAL METHOD:
It use the to find the behaviour of the physical properties on the product using set of defined
differential equations by means of digital computing. It uses the physical properties of the product from the
experimental data and pre-defined set of differential equations to understand the behaviours and effects. It
breaks the problem into discrete parts where it uses set of equations on each discrete part.
Numerical method can be classified into three categories of discretization methods to understand the meshing:
1. Finite Difference Method:
This is the simplest procedure used to derive the discrete form of differential equations. The finite
difference method uses Taylor series using approximate derivatives. It is the simplest form to apply
differential equations on the uniform grids.

46
2. Finite Element Method:
This method was developed at the time of 1960, especially to analyse the structural dynamics
problems. In other terms is based on the weigh residual method. This is a beneficial over the
difference method as it can handle complex geometries and use arbitraries on irregular shapes.
3. Finite Volume Method:
The Finite Volume Method (FVM) is one of the most robust discretization techniques used in CFD.
FVM usually divides the domain into small control volumes (cells, elements) where the variable of
interest is located at the centroid of the control volume. The next part is that it integrates the
differential form of the governing equations (very similar to the control volume approach) over each
control volume using interpolation. The resulting equation that is derive is discretized or discretization
equation. In this manner, the discretization equation expresses the conservation principle for the
variable inside the control volume.
The most prominent feature of the FVM is that the resulting solution satisfies the conservation of
quantities such as mass, momentum, energy, and species. This is exactly satisfied for any control
volume as well as for the whole computational domain and for any number of control volumes.
FVM is the ideal method for computing discontinuous solutions arising in compressible flows. FVM
is also preferred while solving partial differential equations containing discontinuous coefficients.
Use in the research work:
The finite volume method is widely used in the generation of mesh (described below) in ANSYS
Fluent. The research focuses on the behavioural properties of a rear spoiler in air. Hence FVM is the
only method to be used for it.

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3.3 COMPUTATIONAL FLUID DYNAMICS
3.3.1 INTRODUCTION TO CFD
Fluids (gasses and liquid) are governed by partial equations that represent the general laws of
conservation of mass, momentum and energy. CFD is the art of replacing such PDE by set of equations which
can be solved by the digital computers (Kuzmin, 2013).
Computational Fluid Dynamics (CFD) provides quantitative and qualitative predictions of the fluid flow by
means of the following:
 Modelling by applications of mathematics of partial differential equations
 Use of discretion and solution tools i.e. numerical methods.
 Use of the software tools like solvers, pre and postprocessing utilities.
CFD is essential software which enables the engineers to virtually simulate the numerical experiments carried
in the laboratories resulting in less time consuming process and better accurate results. CFD gives an insight
to the pattern of the fluid flow that is difficult to predict with regular experiments, expensive to conduct and
sometimes impossible to study by the regular experiments.
3.3.2 HOW DOES CFD MAKE PREDICTIONS?
The CFD software use mathematical tools to solve the problem which is a pre-set of equations. The
main factor of CFD is
 The researcher who feeds the problem into the computer
 Scientific knowledge that is expressed mathematically.
 The computer code that consists of the algorithms that embodies the knowledge
 Hardware of the computer that performs the calculations
 The researcher who simulates and interprets the data
CFD is a highly disciplinary subject that indulges into the research area and lies at the interface of physics,
applied maths and computer science.

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3.3.3 CFD ANALYSIS PROCESS
CFD analysis process can be summarised in the following steps:
1. Problem Statement:
 It deals with the problem statement of the problem and the fastest way to achieve it.
 It also includes the physical phenomenon to be taken in considerations.
 Operating conditions and the geometry of the body.
 Type of fluid flow i.e. Laminar/ Turbulent/ Multiphase.
 Objective of the CFD analysis i.e. in this research case will be the drag, lift and
downforce.
2. Mathematical Model:
 Defining the symmetries and the flow view.
 Defining the computational domain.
 Formulating the law of conservation of mass, energy and momentum
3. Discretization Process
 It includes the mesh generations, sizing of mesh and inflation
 Changing the mesh structures.
 Time discretization
 Space discretization
4. CFD Simulation
 Generating the simulation.
 Changing the quality of the simulation
5. Post Processing and Analysis
 It is the method of extracting required results from the computation flow field.
 Visualization and debugging of CFD model.
 Validation of the CFD model.
 Using systematic data analysis by means of statistical tools.

49
6. Uncertainty and errors
 Uncertainty includes the lack of knowledge specially the turbulence.
 Acknowledging the local and the global errors.
7. Validation of the CFD models.
 Trying different models or iterations with the boundary and geometric conditions.
 Documenting the findings in report.
 Assessing the uncertainty and errors by performing sensitivity analysis and
parametric study.
8. Validation of CFD Codes
 Examining the computer program by visually checking it and documenting it
 Checking the consistency of the trial.
 Cross checking the results obtained with analytical results.
3.3.4 MESHING
Usually the discretion process converts every continuous system to a discrete one. This means that the
grids or the mesh generation is done to obtain the approx. solution at each discrete grid.
Grid generation of mesh is either of the two types.
1. Structured Mesh generation
2. Unstructured mesh generation
1. Structured mesh generation:
Mesh is generated to fit on the boundaries. The benefit of having structured mesh is to generate the
high and good quality of mesh. This regulates the fastening go the solution algorithm. It is difficult to
have complex domains in mapping from a rectangular grid. Generating the grid is followed by the
physical problem discretion and solved on that grid. The most useful method is to convert the
equations in to the model problem of computational space (figure 36)

50
a. Algebraic grid generation:
Algebraic grid generation is called transfinite interpolation. This method uses the interpolation value
from the boundaries of the computational domain. This can be a beneficial for the grid/mesh density
also in assigning one to one mapping.
However this method generates singularity corner into interior of the domain.
b. PDE Mesh generation:
This method enables the generation of the regular mesh & higher accuracy. There is a single a single
value relationship between the generalised coordinates and simple coordinates. Since the model of
the car in this research project is in 2 dimensional, it will easier to explain.
There is a single value relationship between the generalised coordinates and the simple coordinates.
It can be explained as
ε =ε (x,y) n=n(x,y)
i.e.
x=x (ε,n) y=y( ε,n)
Figure 37 mapping of the physical coordinates on the x, y coordinates.
Usually the functional relationships are determined by the mesh generation process and converted to
the governing equations.
Figure 36 shows a fine structured mesh on a model

51
Conclusion:
This method dominated the CFD methods in the early developed codes. It required more computational
storage. The old fashioned was replaced by the unstructured mesh generation which generated mesh more
automated fashion and is more accurate to determine for the complex geometries.
2. Unstructured mesh generation:
They were initially created for the finite element discretion method. However for the variety of applications
available in the finite volume discretion they are used in meshing the fluid domain. In the finite volume
unstructured meshing there are large possibilities of different mesh sizes ranging from triangles, square in 2D
to the prisms, tetrahedral and bricks (figure 38). The instructed meshing in the final volume discretion follows
mainly four different methods of mesh/ grid generations. These four different methods follow a basic set of
rules mentioned below:
1. Generation of the valid mesh. This means that the mesh should have no holes or self-intersection.
2. Conformation of the mesh with the boundary.
3. Balancing the density of the mesh to control the accuracy and computational requirements.
Figure 38 Generation of unstructured mesh of BMW 3 series model.
The popular methods to generate finite volume meshing in CFD are:
1. Surface Meshing

52
2. Advancing front method
3. Delaunay triangulation method
4. Other methods like paving & plastering, Octree and semi unstructured mesh generation.
Application in the research methodology:
Automatic unstructured meshing has been used in the mesh generation. However the mesh sizes have been
defined to as low values approx. – 1 mm to 2 mm (fig 39, 40) to increase the mesh quantity and quality for
better accuracy in results.
Figure 39 adjusting the element sizes and finding the number of elements
Figure 40 Meshing of the model with minimum 2 & maximum 4 mm element size

53
3.3.5 MESH QUALITY
Mesh quality plays a crucial role in the determination of the accuracy of the results, irrespective of the
types of mesh being used.
1. Mesh Element Distribution:
It is important to have a fine mesh element distribution. Since the domain is discretely defined, the salient
features of the fluid flow depend on the mesh density and distribution. The mesh distribution in the research is
fine and uniform. The automated mesh generated is further modified by the researcher (fig 41, 42).
Figure 42 meshing obtained adjusting sizing
Figure 41 meshing with default configurations

54
2. Cell Quality:
It depends on the skewness and aspect ratio. Skewness is defined as the difference between the shape of the
cell and shape of the equilateral cell of equivalent volume while aspect ratio is the measure of stretching the
cell. In a general rule for a good mesh is to have the triangular mesh with skewness less than 0.95
3.3.6 BOUNDARY CONDITIONS
Boundary conditions serve the important and most required conditions for the mathematical model
(Bakker, 2002). These direct the motion flow of the fluid in the domain. They are also defined as the face zone
in CFD.
There has been significant use of the boundary conditions in the research. The boundary conditions in the
research work consist of the inlet, outlet, similar symmetries, the model car with or without the spoilers and
tyres.
Inlet & Outlet Boundary:
The inlet & outlet boundary is the condition which serves as the input and output or inlet & outlet of the fluid
flow in the domain. They can be of different types, such as:
 For incompressible flows: Velocity inlet and outflow.
 General: Pressure inlet and outlet.
 For compressible flow: Mass inlet and outlet
 Special cases: Inlet and outlet vent.
Most of the time, the selection of the inlet and outlet depends on the type of geometry.
Application in the research methodology:
Since the geometric model is the car and the study needs to find the significant resistive drag forces, the
incompressible flow; input and output boundary condition is applied. This means that the model has an
velocity input and output resembling similar to the wind tunnel.
The other boundary conditions that have been used are the model car. The car surface is the region of
study for the effects of drag forces, down forces, pressure difference. Tyres have also been defined as a

55
boundary. The reason for using tyres separate from the car model is to study the similar forces affecting
the tyres (fig 43).
3.3.7 COMPUTING SETUP
Parallel computing for processing has been used in the processing set up for the models. The reason of
using parallel computing is because; single processing allows solving one discrete problem at one time.
Parallel processing is used to make more than one processing at a time. This is time efficient while double
precision is used to change the magnitude order of the residuals (explained in chapter 4, 4.10).
Figure 43 defining the boundary conditions on geometry in ANSYS

56
3.3.8 CONVERGENCE
Convergence is the way of obtaining accuracy. All the models in the research work have been
converged before they are proceeded to post processing analysis. Convergence is the way of obtaining
accuracy for the model. Number of iterations is made to run to check the convergence of the governing
equations. This is usually estimated by the RMS value depending on the precision of the processor (either
single or double). RMS value usually varies between 106
to 1012
. Once the convergence is achieved, the
results can be more precise.
Application in the research work:
Every model before post processing in the ANSYS Fluent is checked for convergence. This is obtained by the
successfully running the iterations along with the equations. The solutions once converged (fig 44) results in
better accuracy of the results.
Figure 44 obtaining convergence of the operating equations in ANSYS Fluent before post processing
3.3.9 ERRORS
Physical Errors:
Errors that are generated due to the uncertainty in the formulation of the models are called physical errors.
They can be mainly due to mathematical rounding off, initial conditions, and mathematical assumptions or
form

57
Discretization Error:
They occur often from the governing flow equations. Discretization errors can be defined as the difference
between the perfect solution to the discrete equations and analytical solutions to PDE. They can be classified
as:
1. Spatial and temporary discretization of the flow
2. Truncation Error: This error can be defined as the difference between the partial differential equation
and the finite equation.
Programming Errors:
Generally happens due to bugs or referred as mistakes in the programming.
Computer-round off Errors:
These errors can cause inaccuracy or may prevent convergence. Usually when the exact solution could not be
extracted from the discrete equations, they are rounded off as finding the determining the difference between
the two discrete points can consumed huge memory.
Iterative Convergence Error:
This usually happens when slow computing power and time consuming iterations are generally truncated to
the final solutions which lead to the numerical error in the solution called the iterative convergence error.

58
CHAPTER 4
NUMERICAL SETUP
Figure 45 Top and bottom shows analysis of the
models in the ANSYS

59
4.1 INTRODUCTION
The designs were constructed as models in Autodesk Inventor 2014 and exported as .iges extension
format so that the file could be easily simulated on the ANSYS CFD for analysis. The analysis of the CFD is
the results, refined after continuous changes of different spoilers to find the values of coefficients of drag and
lift shown in the next chapter.
The survey is collaborative effort of the research of the designs available in the market from variety of
the websites and articles in magazines. Collectively three designs were selected after the survey. Before
proceeding to the next subtitles and topic there are certain parameters and pre requisite knowledge required.
Pre-requisites
Autodesk Inventor – 2014: The researcher has used Inventor professional 2014 ‘student edition’ for the
purpose of designing the spoilers. Hence it is important to know how to use inventor 2014. Alternatively other
software’s could be used. The final design has to be exported in either of the extension formats of
.iges/.igs/.stp/.step to be able to read the file on ANSYS CFD.
Limitation: Since the car base line model generated is 2 dimensional (dependent on subtopic 1.5) the models
of spoilers are also in 2 dimensional surfaces.

60
4.2 DEVELOPING THE DIGITAL BASE LINE MODEL
4.2.1 GEOMETRY
The concepts developed through the project needs to be applicable on the popular sedan classes and
should be beneficial for an average buyer. As discussed earlier most of the modern day cars experience the
aerodynamic forces. A generic car profile that represents the aerodynamic characteristics and geometry of the
cars in the notchback class is constructed and used as the base line model (BLM) for the research. Even
different car manufacturers have variety in design, geometry and features but substantially do not differ a lot
and have similar aerodynamic characteristics. According to Hucho (Dimitriadis, 2014) the general dimensions
of the car such as the frontal area, length, width and height of the cars do not vary significantly between
manufacturers. However they are optimised moderately to limits by most of the designers. This results is
similar properties, geometry and drag coefficients between the makes. This similarity between the
manufacturers means that the vehicle from one manufacturer closely represents the same aerodynamic
properties of the same class form most manufacturers.
The BLM used for the construction and analysis in the research is BMW 316i ES Saloon, a BMW automobile
car. The model has been chosen because of its god availability of the information. The proportions and
geometry of the BLM has also been extracted to a non-scale model in CAD file to ensure the accurate
aerodynamic simulation of vehicles in the class.
The aim and objective is to generate a CAD file of the BLM notchback which represents the similar properties
of the same class of manufacturers. The BLM is made up in 2 dimensional surface models as dependency and
project limitation of the computer specifications. According to the Katz (Katz, 2006), the average coefficient
of drag among the cars in the notchback class differs from 0.3 to 0.4 with an average frontal area ranging from
1.4m2
to 2.2m2
. It is not the aim to generate the BLM based entirely on the BMW 3 Series sedan mode ;
however the model needs to be a representative of vehicles in the same class.
Finally the methodology is followed by ANSYS CFD observations and calculations.

61
4.3 MODELING IN THE INVENTOR 2014
As mentioned there is variety of CAD software available in the market. For the ease of alterations and
modification it is recommended to use the CAE tool available with the FEA software. As an ease of use the
researcher has used Inventor Professional 2014. The designs of the BLM with and without the spoilers are
created as a 2 dimensional surface profile.
4.4 DESIGNING THE BLM
Original Specifications:
BMW 316i ES Saloon is a sedan class notchback series car. The specification of the car is mentioned
below (BMW UK, 2015). Since the design is two dimensional, the width can be ignored.
BMW 3 16i E Series
Specifications mm
Length 4,624
Height 1,429
Figure Courtesy: BMW UK, website
Using the original specifications, the BLM is designed in the Autodesk Inventor Professional 2014. One of the
features of the software is to generate the model of the actual type in compressing the size ratio. The steps of
design have been explained below.
Figure 46 BMW 3 series dimensions

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Inventor Steps:
Step 1: Initial Setup
Open the software. Since this is our first design of the BLM select “new” and consecutively confirm the
measurements in “standard – mm” for the metrics as shown in the figure 47.
Figure 47 Initial steps using inventor
Step 2: Selecting the design sketch
Once the workspace opens, select the type of sketch that needs to be drawn. This is done by selecting the
create sketch option and selecting “2D Sketch”.
Figure 48 generating a 2D sketch
on inventor

63
Step 3: Selecting the work plane
Once the 2D sketch is selected, generate the XY plane from the origin, displayed on the left panel. This
automatically confirms the XY plane (front) to draw the sketch.
The design of the car has been simplified by importing the picture of the car from the website (BMW UK,
2015). Measuring the size of the car in the picture and comparing the actual size will ease the ratio of model
to original prototype.
Step 4: Importing Image based design
Click on the image option on the tool bar and option for insert image has been selected. The image is imported
into the plane where the sketch is drawn (Autodesk Inventor Professional, 2014)
Figure 49 creating a sketch
Figure 50 using image pointing system to generate BMW 3 series model

64
Step 5: Designing using points
Using the point based way to design; points are clicked on the outer boundary of the car. This means the
point’s line on the surface of the car in the picture. The reason to use the image pointing system is to connect
the points at the end to generate the model car and then delete the picture.
Figure 51 importing the image
Step 6: Finalising the sketch and dimensioning
The dimension of the picture is calculated and the ratio of the actual to the model is derived. In the research
model the scaling of the model to the actual car is 1:28 length and height.
Figure 52 creating the constrained sketch

65
Step 7: Creating the boundary walls
The next step is to create a surface boundary that will be needed for the CFD analysis. This will feature the
boundaries like the inlet and outlet wall. The selection of the boundary is based on the length of the model.
The rear of the model has a length of 5’x’. This means five times the length of the model while the height
thrice of the length.2
The front of the model is at a distance of same length of the model.
Figure 53 creating the boundary walls for ANSYS
Step 8: Generating the Boundary surface
After the boundary layer is created, the final step is to create the boundary patch. This is to make the boundary
separate from the model sketch. In ANSYS the boundary patch acts as the region of fluid flow. Select the
option of boundary patch from the tool bar. Select the region without the sketch of the model to be confirmed
as boundary patch. Finish by confirming.
The selected region highlights with grey effect on the sketch.
2
The length and height of the boundary has been considered 5x and 3x where x is the length of the model. The reason for
selecting the boundary with the variable multiple lengths and height is the reason that the boundary should be well far of
the car. The existence of car should have no effect on the boundary.

66
Figure 54 creating the boundary patch for boundary walls
Figure 55 finishing the boundary patch

68
4.5 MODEL WITH BUILT-IN SPOILER BY MANUFACTURER

69
4.6 MODEL WITH DECKLID SPOILER

70
Most commonly used spoiler in automobile industry is the deck lid spoiler. There are two types of deck lid
spoilers. Spoilers that are added on the trunk of the car separately and the other type of deck lid spoilers with
elevation on the rear end of the trunk.
Figure 56 Deck-lid model spoiler

71
4.7 MODEL WITH OPEN TYPE SPOILER

72
4.8 ANSYS WORKBENCH SETUP
The model in the CAD format needs to be exported to the ANSYS Workbench. Since the model deals
with the research of the fluid flow, the analysis system that needs to be used is the ANSYS Fluent.
Procedure:
 Run the ANSYS Workbench 15
 Select the Analysis tool as Fluid Flow FLUENT CFD from the left tool selection bar.
 On the workspace in the right hand side CFD opens up.
 Simultaneously multiple models for analysis can be used to run and extract the results on one
workbench.
Figure 57 ANSYS workbench
Step 1: Extracting the CAD file
The CAD file is imported to Workbench. In the ANSYS setup for the research work, four models of the BMW
3 E 16 series car (three with manufacturer’s spoiler, deck lid spoiler and open spoiler along with the BLM) are
imported to 4 work space (fig 57).

73
Step 2: Updating the boundary condition for the FLUENT
As explained in the topic 3.7 of chapter 3, every model needs to have assigned the boundary conditions. The
inlet as mentioned will be the velocity inlet since we assume the car is in motion. The models depending on
whether BLM or spoiler models are defined as the car body.
 Select the edge selection from the top tool bar as shown in figure. This allows selecting the edges and
naming them. Manually feed the names. As for this research work all the four models have left wall as
Inlet, right wall as outlet, top and bottom wall as symmetries, model without the tyres as car body and
tyres separately as tyres in named selection. This is to ease the post processing and finding the result
as well as identifying the boundaries during post processing.
 BLM Geometry setting :
Figure 58 generating the named boundaries

74
 Manufacturer’s model with built-in spoiler (Geometry settings)
Figure 59 generating the named boundary and geometry condition in built-in the model

75
Similarly for Deck-lid and Open spoiler models
Figure 60 generating the boundaries for Open Spoiler model
Figure 61 generating boundary conditions for deck-lid spoiler model

76
Step 3: Setting the Meshing
Topic 3.5 in chapter 3 describes two types of meshing. ANSYS Fluent automatically uses unstructured
meshing. In the models the automated meshes needs to be adjusted3
.
 Select the option of mesh from the left hand tool box
 Select the option of sizing from the bottom menu.
 From the sizing, change the minimum size of the mesh from automatic to manually fed value in mm.
 Update the project to observe the change.
BLM Meshing
3
All the adjustments for the meshing in the models have been defined.
Standard 1 mm for the minimum size and 2 mm for the maximum size
of the mesh elements have been taken in considerations.
Figure 62 default mesh
Figure 63 adjusting the mesh to 1 mm minimum and 2 mm maximum

77
BLM updated mesh
Similarly the other models are updated top fine mesh.
Manufacturers’ built in spoiler model mesh
Figure 64 Updated mesh of BLM
Figure 65 updated mesh of built-in model spoiler

78
Deck lid Spoiler model
Open Spoiler model with updated mesh
Figure 66 updated mesh of deck-lid spoiler
Figure 67 updated mesh for open spoiler

79
Step 4: FLUENT Setup
After all the alterations and adjustments are done in the meshing, the set up needs to be checked and modified
before running the solutions.
This is done by the following ways (figure 68)
 Select the setup option from the work space.
 Select 2D for dimension
 Use Double Precision for options.
 For processing options select the parallel (refer Chapter 3) & use the value 4
Figure 68 Fluent setup

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4.9 POST PROCESSING SET UP
The analysis on the fluent is obtained with modifications and moderations in the processing setup.
This includes the selection of density of the fluid, assigning a fluid inlet speed, checking the convergence of
the model. All the models are followed with the steps below before analysing the results.
General Settings:
Two-equation turbulence models are very widely used, as they offer a good compromise between numerical
effort and computational accuracy. In two equation system, both the velocity and length scale are solved using
separate transport equations (hence the term ‘two-equation’). The k- Ɛ and k-ω are which are the two-
equation models use the gradient diffusion hypothesis to relate the Reynolds stresses to the mean velocity
gradients and the turbulent viscosity. The turbulent viscosity is modelled as the product of a turbulent velocity
and turbulent length scale. The solutions from the transport equation provide the turbulent velocity scale
computed from turbulent kinetic energy of the two equation model. There are other models which uses more
than two equation model example Transition SST (4 –Equations), LES, Reynold’s stress (7 equations). They
tend to have more accuracy but are more time consuming processing.
General Solver:
In the research work we will use, pressure based solver type. The reason for using pressure base
solver is: The pressure-based and density-based approaches differ in the way that the continuity, momentum,
and (where appropriate) energy and species equations are solved. Pressure-based solver traditionally has been
used for incompressible and mildly compressible flows. The density-based approach, on the other hand, was
originally designed for high-speed compressible flows (shown in fig 69).
Figure 69 applying the general settings

81
Choosing absolute or relative velocity formulation
It is used to result most of the flow domain having velocities in that frame. Hence forth It reduces the
numerical diffusion in the solution and generate more accuracy.
Usually absolute velocity formation is used for the applications where the flow in the domain is not
rapidly rotating for example a large room.
Application in research
Since the boundary condition is quiet large in the research model, we will use absolute velocity
formulation.
However the relative velocity formulation is used where the fluid domain is rapidly rotating for
example a mixer tank.
Energy Equation: It is used where there is a variance of the temperature effect in the fluent analysis.
Since the research model focuses just on reducing the lift and drag forces, we can ignore the energy
equation.
Using Steady time: It refers to flow being steady with the variance of time and takes lesser time to
converge.
Figure 70 changing the velocity formulation

82
Figure 72 adjusting the fluid selection
1. Model calculation Selection:
Set the fluid selection as air with constant density with K- omega of 2eqn from viscous laminar shown below.
Figure 71 adjusting the model settings
2. Fluid Value setup
Select the fluid that will be used to analyse the model as air with constant density of 1.225 kg/m3
. The reason
for selecting the constant density of the fluid is explained in chapter 3. [] figure []

83
3. Assigning values to the named boundary
It is important to assign values to the boundaries generated. The inlet wall needs to be velocity inlet, outlet
wall to be pressure outlet. All the models have been assigned a value of 60Km/hr i.e 16m/s of velocity inlet.
4. Running the solution initiation
This allows checking the model for any possible errors. Select the solution initialization and select Hybrid
Initialization as shown in figure
Figure 74 selecting the initialization
Figure 73 assigning the input velocity (similar for all 4 cases)

84
Difference between hybrid initialization & Standard initialization
Hybrid Initialization: It is a method of initialization in ANSYS Fluent. Hybrid initialization uses a mixture
of different interpolation methods. Using Laplace equation it solves the velocity and the pressure fields. Other
variables like the temperature, turbulence, specific fractions will be patched automatically depending on the
interpolation and domain averaged value.
Standard Initialization: This is the method of initialization in ANSYS Fluent by manually assigning the
variable and value. This can be used to monitor small changes and assign difference in pressure, velocity or
turbulent kinetic energy.
5. Running Calculations:
This feature enables to run assigned number of iterations. It is useful to find the convergence (explained in
chapter 3 [] ) of the equations being used in the CFD. Once the solution is converged, the accuracy of the
result increases. All the models have been assigned for 1000 iterations.
Figure 75 selecting number of iterations for accuracy

85
Figure 76 shows converging the equations
Figure 77 showing the converged equations

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4.10 RESIDUALS & ERRORS
Residuals:
When solver iterations are calculated, the residual sum of each conserved variable is computed and
stored. This helps in recording the convergence history. In ideal process with infinite precision the residuals
tend to be zero when the convergence occurs. However the scenario in actual computing is different. The
residuals tend to be small valued and then stop changing. Their magnitude differs with single precision to
double precision ranging from six to twelve orders of magnitude respectively before rounding off.
Errors:
2D geometry analysis on Fluent has certain errors on the pressure and the velocity contours. Since the
geometry defines a boundary layer, it assumes that the region in the front is closed with the tyres and the
bottom symmetry.

87
CHAPTER 5
ANSYS FLUENT RESULTS & ANALYSIS

88
5.1 INTRODUCTION
Every model is run on the ANSYS Fluent to obtain a simulated picture which shows different
physical properties that affect the model. The coloured picture depicts the values of the physical properties at
the instant. This half of the chapter is to analyse the models with the results obtained in the pictorial form and
find the coherence with the graphs and physical theories.
5.2 ANALYSIS FOR BLM
Velocity Contours:
The velocity magnitude is the instantaneous speed of the model car. The region of light brownish yellow
colour shows the normal velocity of the fluid (air) in the domain. As the model car travels with 16 m/s the
velocity of the air changes with the position of the car. In the figure 78, the air has velocity of 15 m/s. As the
air along the car model is brought closer towards the bonnet, the velocity rise from 20 m/s of the orange patch.
It keeps increasing to 24.20 m/s on the top roof surface of the car in pale red patchy region and drops slowly
on the top surface about a distance of almost twice the length of the model.
On the bottom part of the model car, the velocity of the air exhibits very low or negative value of no air
movement. This is shown as region of ocean blue colour having velocity of 4m/s to -3.79 m/s. This is one
limitation in 2D model. In real case, the model will have fluid velocity on the bottom surface too thus having a
value greater than zero. The error is explained in chapter 3, topic errors.
Figure 78 Velocity magnitude picture from Fluent

89
Pressure Contours:
Figure 79 pressure contours
Figure 80 shows static pressure graph

90
Static pressure:
From the image it can be observed that the static pressure on the body of the model car fluctuates a lot on its
boundaries. The front region of the car exhibits an extensive pressure. The region for the high pressure is
explained in the topic of errors and residuals in Chapter 4, topic 4.10.
Region of stagnation:
The stagnation point can be seen in the front of the car figure 81, which has ‘V’ shaped cut from the body
panel to the bumpers. This is the region which comes in contact to the air at first instance when the car is in
motion. The model shows a pressure of 250 Pa.
Relation of the image along with the graph
As the design is further analysed the static pressure fluctuates from 210- 200 Pa. to around 105 Pa. at the
lower surface of the model car. Similarly for the top surface of the car the pressure varies from the 5 Pa. at the
top bonnet drops, increases to air pressure taken as standard 0 Pa, again drops to about -225 Pa.
Turbulence Contours:
Stagnation point
Figure 81 shows the stagnation point
Figure 82 shows turbulence graph of the BMW Body and the tyres (in red)

91
5.3 ANALYSIS FOR MANUFACTURER MODEL
Velocity Contours:
As explained in the model car without any spoiler, the figure 84 below shows the velocity magnitude of the
model with built-in spoiler. The magnitude of velocity of the air as it hits the car bonnet top surface starts to
increase from 16.40 m/s and reaches at a maximum of 24 m/s or greater on the surface of the bonnet. Similar
phenomenon happens at the top surface of the model car roof. Further moving with the top geometry of the
model car to the rear part the velocity approaches to 0. Both the figures 84 & even in the x direction figure 84
the velocity of the air reaches to 0. This is a case of error and residuals explained in chapter 3, topic 3.3.9
Magnitude:
Figure 84 Velocity magnitude in manufacturer’s –built in model
Figure 83 Velocity in X axis

92
Figure 85 shows velocity in Y direction
The figure 85 above shows the velocity of the air in Y direction. The frontal region shows a high velocity of
air reaching up to 19.20 m/s from 7.3 m/s in the regions of the change in geometry. Since the flow of air is in
x direction, there is more contribution of the velocity contours toward the x axis opposite to the motion of the
model.
Pressure Contours:
The region of the static pressure across the manufacturer model remains similar with high concentration of the
pressure around the frontal types. The point of stagnation does not change. However the region of the pressure
across the body has minute changes from the frontal to the rear geometry.
Figure 86 shows the pressure contours

93
Comparing the picture with the graph:
The lower graph with the position depicts the top surface of the model car with manufacturer’s built-in
spoiler. The graph of the static pressure increases from a negative -155 Pa. approx. pressure (shown in slight
ocean blue colour region) to the normal environment pressure of 1 Pa. shown in greenish effect colour.
Further moving along the geometry to the top surface the pressure drops exactly where the dash broad screen
and the roof meet dropping to -245 Pa. (in royal blue colour). With the further observation moving towards
positive x direction the pressure starts to increase and come to normal air pressure.
The same happens to the bottom surface shown in the upper graph. The value of pressure increase to
approximately 201 Pa. maximum and further beyond the front tyres it starts to fall to the normal air pressure
till it reaches the rear of the car model.
Figure 87 shows the static pressure graph
Figure 88 shows same stagnation region as the base line model

94
Error in model CFD:
The pressure starts to increase and keeps on increasing to approximately 201 Pa. This seems to show that the
velocity of air is very less or negligible. This is an example of error in 2D geometry. Since in 2D geometry,
the computer assumes the boundary to be closed and no possibility of the air movement. However in reality is
a different case. The air passes underneath the car trunk. Thus the pressure should not be that high which can
make the model car lose control.
As discussed in chapter 2 of general concept and theories, turbulence generated by the built-in model of the
car is different than the generic BLM. The turbulence at the rear of the built-in spoiler model makes a ‘V’
shape. The region of higher turbulence is present almost thrice the distance of the rear of the model.
Comparing the model picture with the graph:
The region of the higher turbulence can be observed around the region of higher chaotic properties. The
turbulence reaches to a significant 26.20 m2
/s2
from normal of 0. And slowly diffuses back.
Figure 89 shows the turbulence in case 2

95
The region of high turbulence is shown by the red dotted line in the picture.
Reason of the V shaped push and higher turbulence.
Since the built-in model of car has a spoiler with steep divergence on the top, it diverts the air from the rear
trunk of the car. This indirectly diverts the flow. Once the flow is diverted and it joins again the top velocity,
causing different flow mixtures. Once the velocity of the air flow reduces, it introduces low momentum
diffusion, high momentum convection & rapid variation of pressure and flow at that instant of time and
distance generating higher turbulence.
Figure 90 shows the kinetic energy of the turbulence region

96
5.4 ANALYSIS FOR DECK LID SPOILER
Velocity Contours:
The magnitude of the velocity increases from 16 m/s to 24.60 m/s (Yellow to red region figure 91) as it hits
the bonnet of the car. Thus it reduces the pressure which can be visible when we compare the static pressure
pictures and data. The velocity contours keep on increasing as we move further on the top surface towards
positive Y direction. As the air strikes the top surface it increases the velocity and then to move in a parabolic
path till it reduces.
However there is a reduced velocity magnitude at the bottom surface of the car and at the rear part. The
velocity reduces to 1.23 m/s and has a curved line shaped at the rear in royal blue colour. There is mixture of
different velocity magnitudes at the rear ranging from 16m/s to 4.91 m/s
Figure 91 shows velocity magnitude in deck-lid spoiler
Figure 92 shows velocity in x direction

97
However the velocity in the x direction shows least circulation around the spoiler region. And variation of the
velocity magnitude figure shows velocity changes of patchy region ranging 2.46 m/s to or below 4.91 m/s
Pressure Contours:
The pressure distribution for the deck-lid model of the car is quite different when compared to the previous
two models. The region of high pressure is the frontal part of the car. The pressure rises to a stagnation value
of 280 Pa. in the frontal part.
As we move along the geometry of the car, since the velocity increase, the pressure decreases at the bonnet of
the car. This can be established by the Bernoulli’s equation [] where velocity increase, the pressure reduces.
Patchy region within the box which
shows variation in the velocity
magnitude of the air near the spoiler.
Figure 93 enlarged picture showing the lesser velocity
around the model
Figure 94 showing the pressure contours for deck-lid model

98
Again comparing the picture 94 and the graph 95 shows the similar fluctuation in the pressure. The top of
surface of the model shows negative distribution of the pressure over the bonnet and increases to the normal
pressure. Further moving over the top surface the dark blue patchy region shows the drop in the pressure to
almost -240 Pa. approx...
The turbulent contours shown in the picture is different than the other two previous models. The region of
turbulence is wide spread showing a ovular patchy region with core of red region of 19.50 m2
/s2
and gradually
decreasing to 9.77 m2
/s2
and finally into the blue region of value to 0. This time the region of turbulence is
further away from the vehicle almost more than double the model length.
Figure 95 showing the static pressure region in graph
Figure 96 shows turbulence in the deck-lid spoiler car

99
5.5 ANALYSIS FOR OPEN STYLE SPOILER
Velocity Contours:
The velocity magnitude for open style spoiler also varies with the BLM and other two models. The velocity
magnitude also varies as with the other model along with the geometry. The velocity around the bonnet
increases up to 23.20 m/s falls little around the start of the dash board and again increases.
The region around the spoiler shows a velocity magnitude of between 2.44 m/s. The region behind the rear of
the car shows a drop in the velocity. Slowly the velocity magnitude increases too an resumes to the 16 m/s
Figure 97 shows the velocity contours for open style spoiler model car
Figure 98 shows the velocity in x direction

100
Error:
The region around the front end of the model, the rear end as well as the base shows very little movement of
the air. This is the limitation of using 2D model. The computer assumes that the regions are fixed and closed.
However in the realistic model or 3D analysis, there exists velocity underneath the car.
Pressure Contours:
The pressure distribution across the geometry of the open spoiler model is again different to that of the others.
However the region of stagnation remains the same. Pressure decreases at the top surface of the bonnet where
the velocity is high and on the start of the roof top. The pressures around two regions are approx... -213 Pa.
Error:
The region of stagnation is similar to the region of least velocity (using Bernoulli’s equation). This is because
of the geometrical limitation of the 2D model which assumes the boundary to closed and definite underneath
the car. The region has a very high pressure value of 207 Pa making it unrealistic figure 100. The same reason
follows for the underneath of the model car which shows value around 141 Pa.
Unrealistic region around the tyres
showing very less or no velocity
magnitude.
Figure 99 shows enlarged image of the velocity magnitude
Figure 100 shows the pressure contours in open style spoiler model

101
Comparison of the picture with the graph:
The graph shows exactly what the figure depicts in contours. The lower graph shows the top surface of the car
while the top graph shows the lower surface. As we analyse the pressure values from the region of low
pressure it increases up to a normal standard air pressure value and again drops around the roof and slowly
regains.
The region around the spoiler has a pressure value ranging in between -40 Pa.
The region of turbulence is quiet near to car rear. It shows an unfavourable or chaotic region of velocity,
regaining the momentum. The region of high turbulence can be seen in patchy red and slowly regaining to
normalcy.
Figure 101 shows the graph for the static pressure along with the geometry
Figure 102 shows the turbulence contours for the open style spoiler model

102
5.6 VELOCITY MAGNITUDE COMPARISION TABLE:
Figure 103 shows the velocity magnitude. From top to bottom Case 1, 2, 3, 4 respectively

103
Table 1 Upper body velocity magnitude for case 1, 2, 3, 4
Comparison Table:
Table 2 Lower body velocity magnitude for cases 1, 2, 3, 4
Model
Upper Front
Velocity magnitude
in m/s
Upper Rear Velocity
magnitude in m/s
Upper region of high velocity magnitude
BLM –
Normal car
16 – 24
Gradually decreases from
24- 20 and then to 16
Red Patchy areas on the surface of the car
bonnet, top surface where geometry changes
i.e. dashboard meets the roof.
Built-in
spoiler
model
16 – 24
Decreases from 23 to 20
and finally to 16
Shown in the dark red coloured region on the
bonnet and starting of the roof surface.
Deck-lid
Spoiler
model
16 – 24
Decreases leaving a large
area on the top of about a
value 22
Bonnet of the car and almost more than
twice the distance of the car on the top
surface.
Open
Spoiler
model
16 – 24
Follows a gradual
decrease from 23 - 16
Same region as of the BLM model.
Model
Lower front velocity
magnitude in m/s
Lower rear velocity
magnitude in m/s
Lower region of low velocity
magnitude
BLM –
Normal car
6.01 – 1.81
4.61to negative 2.39
The region is showed by the patchy blue
colour changing from light blue to dark
blue colour.
Built-in
spoiler
model
3.82 - 0
9.81 to a value of 0
Shown in the light regions to the dark
effect.
Deck-lid
Spoiler
model
2.66 - 0
Decreases from a value
of 2.46 to a value of zero.
The entire lower region shows a very low
velocity magnitude from 4.91 to zero in
blue regions.
Open Spoiler
model
4.89 - 0 Decreases from 1.22 to 0 Same region as of the BLM model.

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5.7 PRESSURE COMPARISION:
Figure 104 shows the pressure contours for
cases 1, 2, 3, 4 respectively

105
Pressure Graphs:
Figure 105 shows the pressure graphs for cases 1, 2, 3, 4 respectively

106
Table 3: Upper body pressure comparison for cases 1, 2, 3, 4
Table 4: Lower body pressure comparison for cases 1, 2, 3, 4
Model
Upper front pressure in
Pascal
Upper rear pressure in
Pascal
Discussion of upper region of
pressure
BLM –
Normal car
Region of low pressure is
visible of about 0 – 5
Shows a very low pressure
on the top roof surface of
the model
The top surface shows a variation of
the pressure from low to the normal
air pressure.
Built-in
spoiler model
Region of the low
pressure is visible similar
to the BLM model
Shows the region of the
distributed low pressure
around the spoiler about -
85
The top region shows a greater area
of the low pressure since the
velocity magnitude is very high
Deck-lid
Spoiler model
Region of low pressure
starts at the same region
as shown in the BLM
Top surface has the
minimum pressure
The pressure around the upper
region stays at the same pressure of
-92.50 around the spoiler
Open Spoiler
model
The region has less low
pressure compared to the
other models.
The roof of the car has the
lowest pressure varying
from -235
There is a patch of low pressure of
about 102 over the spoiler.
Model
Lower front pressure
in Pascal
Lower rear pressure in
Pascal
Discussion of lower region of
pressure
BLM –
Normal car
Region in the front of
the car shows a
stagnation of 205
The lower rear region
shows the pressure
varying about a value of -
102
The region underneath the trunk of
the car is an unrealistic image
showing high pressure
distribution.
Built-in
spoiler model
The region of high
pressure is similar to the
BLM
The lower rear pressure is
low with similar to the
upper rear part.
The pressure underneath the trunk
lies between 35
Deck-lid
Spoiler
model
The region of front part
exhibits the same high
stagnation point.
The pressure in the rear
part is similar to the BLM
model.
The pressure underneath the trunk
of the car is around -31.17 which
unrealistic.
Open Spoiler
model
The stagnation point is
same.
The rear lower part has
the same values of
pressure as the upper rear
part with few difference.
The pressure under the trunk is
about 119 which is again not
idealistic due to 2D geometry
limitation and error.

107
5.8 TURBULENCE COMPARISION
Figure 106 shows the turbulence regions in cases 1, 2, 3, 4 respectively

108
Comparison table:
Table 5: Comparison table for turbulence in cases 1, 2, 3, 4
Wake Turbulence:
Usually wake turbulence is formed behind the aircraft as it passes through the air. Similarly wake turbulence
is formed behind the air foils of the cars. But these are so less that it can be considered no effect on the other
automobiles on the road.
Model
Turbulence region/
value
Description
BLM –
Normal car
The region of turbulence
is way behind the car.
The turbulence does not have or matches with the streamline flow.
The wake region is quiet near to the car rear field.
Built-in
spoiler model
The region of the
turbulence is not very far
from the model.
The wake region and the area of the recirculation lies very close
approximately twice the distance of the car.
Deck-lid
Spoiler model
The turbulent region is
quiet widespread almost
very far
The turbulent region shows a stream line recirculation. The wake
is widespread but obviously stream lined.
Open Spoiler
model
The region has the similar
effect as that of the Deck-
lid Spoiler.
The turbulent region follows the similar streamline flow. The
wake field is quiet far from the model car and hence would have
negligible effect on it.
Figure 107 shows region of wake turbulence

109
5.9 RESULTANT FORCES
Table 6: Resultant forces on the model car body for cases 1, 2, 3, 4
Representation is done in (x, y, z) coordinate system.
Table 7: Resultant forces from tyres for cases 1, 2, 3, 4
Model Pressure Forces (Net) N Viscous Forces (Net) N Total Forces (N)
BLM – Normal
car
(-1.0449, 31.3209, 0) (0.1317, 0.04291, 0) (-0.8832, 31.3685,0)
Built-in spoiler
model
(-1.007358, 22.5983,0) (0.15941, 0.04293, 0) (-0.847946, 22.64123, 0)
Deck-lid Spoiler
model
(-1.114174, 23.351746, 0) (0.1559896, 0.03976, 0) (-0.95818, 23.39153, 0)
Open Spoiler
model
(-1.1551695, 31.0380, 0) (0.1558332, 0.0416366, 0) (-0.99683402, 31.0796, 0)
Model tyres Pressure Forces (Net) N Viscous Forces (Net) N Total Forces (N)
BLM – Normal
car
(5.710411, 0.24515, 0) (0.020252245, -0.00025567, 0) (5.7306627, 0.24489, 0)
Built-in spoiler
model
(5.5206733, 0.30913989, 0) (0.016064, -0.0005722, 0) (5.536738, 0.3085676, 0)
Deck-lid Spoiler
model
(5.56199, 0.075365, 0) (0.017534, -0.00045973, 0) (5.579523, 0.074950, 0)
Open Spoiler
model
(5.741489, 0.2409329, 0) (0.02036237, 0.000258597,0) (5.761852, 0.2406744, 0)

110
Total drag and lift forces:
Table 8: Total drag and lift forces in cases 1, 2, 3, 4
Comment from the table:
From the above comparison of the total drag forces and the total lift we can say that all the three models have
contributed somehow to reduce the drag and lift. However spoiler which is closed with the rear trunk has been
beneficial in reducing the drag and the lift up to 10 N from the actual model without any spoiler.
Model tyres Total Drag Forces (N) Total Lift Forces (N)
BLM – Normal car 4.8474577 31.608742
Built-in spoiler model 4.6887922 22.949804
Deck-lid Spoiler model 4.6213429 23.466435
Open Spoiler model 4.7650178 31.320337

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CHAPTER 6
CONCLUSION & FUTURE SCOPE
Figure 108 figure of a deck-lid spoiler at rear of BMW 3 series.
Picture courtesy: BMW website

112
Conclusions
 Different types of cars in sedan class use rear trunk spoilers. The research focused on the application
of the rear spoiler designed in 2D and explained in CFD processing tools which address the problem
statement by allowing the model car ‘BMW 3 series’ to withdraw its drag and reducing the lift. This
has the effect of streamlining the model car to attain the lowest possible drag and lift when required in
high velocity.
 The system was successfully simulated and compared against the performance of the BLM and other
three models. The CFD simulation allowed a direct comparison of the three different types of spoiler
along with the car model. This comparison also helped in comparing the post process values obtained
from ANSYS Fluent. The first set up was to analyse the background and possible scope of the product
in the automobile industry.
 The research focused generalising the basic concepts of the governing laws and theories of the fluid
flow around the spoilers. This helped in establishing the concept with the product. Apart giving a
broad introspect to the concepts, this was followed by the research methodology which dealt with the
basic approach of the research work. Being quantitative in nature and mixture of qualitative
techniques resulted in the scope of understanding the different ways of approaching the problem
statement.
 Understanding prediction methods and reason of using the numerical method is well established by
the fact that, the problem statement needed a discretization technique to approach the solution. This
was a great leap by using the FVM (Finite Volume Method). Using the digital computing, the solution
could be achieved.
 As the geometry is obtained, it is scaled to a smaller model. Using inventor, the design for the
different models was obtained. The pre-processing setup was used to analyse the standard tools used
in the fluent setup.
 The research post processing chapter 5 – Fluent results and analysis shows the region of the high and
low velocities of air, turbulent region of the car models and pressure analysis across the geometry of
the models.

113
 The resultant comparison of the drag forces and lift forces well establish that a normal car without the
rear spoiler has higher values than that of the drag and lift compared to the model with the spoilers.
Compared to other models, the built-in model provided the best results for the aerodynamic forces.
Future Scope
This research project is a general introduction towards the application of aerodynamic rear spoilers in the
Sedan class cars. Because of this a lot of possible future work can be conducted undertaking this project as a
base to initiate.
For instance in order to understand the application of aerodynamics in a two dimensional car surface,
simulations can be carried out with different model of spoilers ranging from built-in and open type can be
created. Mapping of the pressure distribution, velocity contours and turbulence behind the cars with ANSYS
CFD Fluent simulation can be a leap to map the aerodynamic forces. This is a very useful tool in obtaining the
information about the trends and behaviour of the complete car in motion. As mentioned in the result section;
simulated model of the BLM and the models with spoilers can generate results that can be dimensionally
analysed, however the accuracy of the result depends on the limitations and errors of the two dimensional
geometry.
On the other hand if the generic dimensions are used for the same simulation, the results could be applied to
any Sedan class cars exceeding 4.5 metres in length. Another important point would be confirming and
validating the conclusion of the rear spoiler not working properly as a result of multiple simplifications
applied to the future model. Finally due to the heavy unsteady behaviour of the vehicles around wake
turbulent region can be investigated including unsteady simulations which could be a future aspect or
compliment to tis research project(obviously in two dimensional Analysis) along with the wind tunnel test.

114
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J. Smagorinsky, General circulation experiments with the primitive equations. I. The basic experiment,
Monthly Weather Review 91 (1963) 99–164.
S. Murakami, Overview of turbulence models applied in CWE-1997, Journal of Wind Engineering and
Industrial Aerodynamics 74–76 (1998) 1–24.
S.E. Kim, Y. Dai, E.K. Koutsavdis, S.D. Sovani, N.A. Kadam, K.M.R, Ravuri, A Versatile Implementation of
Acoustic Analogy Based Noise Prediction
Approach, AIAA 2003-3202, 2003.
S.V. Patankar, Numerical Heat Transfer and Fluid Flow, Hemisphere Publishing Corp., Washington
DC, 1980.
H.K. Versteeg, W. Malalasekera, Introduction to Computational Fluid Dynamics: The Finite Volume Method,
Prentice-Hall, Upper Saddle River, NJ, 1995.
P. Bergamini, M. Casella, D.F. Vitalt, Computational Prediction of Vehicle Aerodynamic Noise by
Integration of CFD Technique with Lighthill’s Acoustic
Analogy, SAE 970401, 1997.
B.R. Munson, D.F. Young, T.H. Okiishi, Fundamentals of Mechanics, forth ed., John Wiley & Sons, 2002.
R.H. Barnard, Road Vehicle Aerodynamic Design, Longman, 1988.

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About Spoilers | What Is a Car Spoiler. (n.d.). Retrieved from http://www.171car.com/about/
ANSYS Inc. PDF Documentation for Release 15.0. (n.d.). Retrieved from
http://148.204.81.206/Ansys/readme.html
Automotive Aerodynamic Efficiency Simulation with Exa PowerFLOW. (n.d.). Retrieved from
http://www.exa.com/aerodynamic_efficiency.html
The Bizarre German Car That Was Ultra-Aerodynamic?And Totally Impractical | WIRED. (n.d.).
Retrieved from http://www.wired.com/2014/09/german-aerodynamic/
Design Real. (n.d.). Retrieved from http://design-real.com/spoiler/
Drag Queens: Aerodynamics Compared ? Comparison Test ? Car and Driver. (n.d.). Retrieved from
http://www.caranddriver.com/features/drag-queens-aerodynamics-compared-comparison-test
Spoiler Alert: A History of Downforce. (n.d.). Retrieved from http://jalopnik.com/5659723/spoiler-
alert-a-history-of-downforce
Wings/Spoilers: You're probably doing it wrong. (n.d.). Retrieved from
http://oppositelock.jalopnik.com/wings-spoilers-youre-probably-doing-it-wrong-1665312667

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APPENDICES
APPENDIX 1
What Are the Navier-Stokes Equations?
The Navier-Stokes equations govern the motion of fluids and can be seen as Newton's second law of motion
for fluids. In the case of a compressible Newtonian fluid, this yields where u is the fluid velocity, p is the fluid
pressure, ρ is the fluid density, and μ is the fluid dynamic viscosity. The different terms correspond to the
inertial forces (1), pressure forces (2), viscous forces (3), and the external forces applied to the fluid (4). The
Navier-Stokes equations were derived by Navier, Poisson, Saint-Venant, and Stokes between 1827 and 1845.
These equations are always solved together with the continuity equation:
The Navier-Stokes equations represent the conservation of momentum, while the continuity equation
represents the conservation of mass.
How Do They Apply to Simulation and Modeling?
These equations are at the heart of fluid flow modeling. Solving them, for a particular set of boundary
conditions (such as inlets, outlets, and walls), predicts the fluid velocity and its pressure in a given geometry.
Because of their complexity, these equations only admit a limited number of analytical solutions. It is
relatively easy, for instance, to solve these equations for a flow between two parallel plates or for the flow in a
circular pipe. For more complex geometries, however, the equations need to be solved numerically.
Example: Laminar Flow Past a Backstep
In the following example, we numerically solve the Navier-Stokes equations (hereon also referred to as "NS
equations") and the mass conservation equation in a computational domain. These equations need to be solved
with a set of boundary conditions:

119
The fluid velocity is specified at the inlet and pressure prescribed at the outlet. A no-slip boundary condition
(i.e., the velocity is set to zero) is specified at the walls. The numerical solution of the steady-state NS (the
time-dependent derivative in (1) is set to zero) and continuity equations in the laminar regime and for constant
boundary conditions is as follows:
Velocity magnitude profile and streamlines.
Pressure field.

120
Different Flavours of the Navier-Stokes Equations
Depending on the flow regime of interest, it is often possible to simplify these equations. In other cases,
additional equations may be required. In the field of fluid dynamics, the different flow regimes are categorized
using a non-dimensional number, such as the Reynolds number and the Mach number.
About the Reynolds and Mach Numbers
The Reynolds number, Re=ρUL/μ, corresponds to the ratio of inertial forces (1) to viscous forces (3). It
measures how turbulent the flow is. Low Reynolds number flows are laminar, while higher Reynolds number
flows are turbulent.
The Mach number, M=U/c, corresponds to the ratio of the fluid velocity, U, to the speed of sound in that
fluid, c. The Mach number measures the flow compressibility.
In the flow past a backstep example, Re = 100 and M = 0.001, which means that the flow is laminar and
nearly incompressible. For incompressible flows the continuity equation yields:
Because the divergence of the velocity is equal to zero, we can remove the term:
from the viscous force term in the NS equations in the case of incompressible flows.
In the following section, we examine some particular flow regimes.
Low Reynolds Number/Creeping Flow
When the Reynolds number is very small (Re≪1) , the inertial forces (1) are very small compared to the
viscous forces (3) and they can be neglected when solving the NS equations. To illustrate this flow regime, we
will look at pore-scale flow experiments conducted by Arturo Keller, Maria Auset, and Sanya
Sirivithayapakorn of the University of California, Santa Barbara.

121
About the Experiment
The domain of interest covers 640 μm by 320 μm. Water moves from right to left across the geometry. The
flow in the pores does not penetrate the solid part (gray area in the figure above). The inlet and outlet fluid
pressures are known. Since the channels are at most 0.1 millimeters in width and the maximum velocity is
lower than 10-4
m/s, the maximum Reynolds number is less than 0.01. Because there are no external forces
(gravity is neglected), the force term (4) is also equal to zero.
Therefore, the NS equations reduce to:
Modeling the Experiment
The below plot shows the resulting velocity contours and pressure field (height).

122
The flow is driven by a higher pressure at the inlet than at the outlet. These results show the balance between
the pressure force (2) and the viscous forces (3) in the NS equations. Along the thinner channels, the impact of
viscous diffusion is larger, which leads to higher pressure drops.
Running such simulations using the NS equations is often beyond the computational power of most of today's
computers and supercomputers. Instead, we can use a Reynolds-Averaged Navier-Stokes (RANS) formulation
of the Navier-Stokes equations, which averages the velocity and pressure fields in time.
The Reynolds-Averaged Navier-Stokes (RANS) formulation is as follows:
Here, U and P are the time-averaged velocity and pressure, respectively. The term μT represents the turbulent
viscosity, i.e., the effects of the small-scale time-dependent velocity fluctuations that are not solved for by the
RANS equations.
The turbulent viscosity, μT, is evaluated using turbulence models. The most common one is the k-ε turbulence
model (one of many RANS turbulence models). This model is often used in industrial applications because it
is both robust and computationally inexpensive. It consists of solving two additional equations for the
transport of turbulent kinetic energy k and turbulent dissipation ϵ.
To illustrate this flow regime, let us look at the flow in a much larger geometry than the pore scale flow: a
typical ozone purification reactor. The reactor is about 40 meters long and looks like a maze with partial walls
or baffles that divide the space into room-sized compartments. Based on the inlet velocity and diameter, which
in this case correspond to 0.1 m/s and 0.4 meters respectively, the Reynolds number is 400,000. This model is
solved for the time-averaged velocity, U; pressure, P; turbulent kinetic energy, k; and turbulent dissipation, ϵ:

123
The results show the flow patterns, flow velocity, and turbulent viscosity μT.
Flow Compressibility
The flow compressibility is measured by the Mach number. All the previous examples are weakly
compressible, meaning that the Mach number is lower than 0.3.
Incompressible Flow
When the Mach number is very low, it is OK to assume that the flow is incompressible. This is often a good
approximation for liquids, which are much less compressible than gases. In that case, the density is assumed
to be constant and the continuity equation reduces to ∇⋅u=0. The creeping flow example showing water
flowing at a low speed through the porous media is a good example of incompressible flow.
Compressible Flow
In some cases, the flow velocity is large enough to introduce significant changes in the density and
temperature of the fluid. These changes can be neglected for M<0.3. For M>0.3, however, the coupling

124
between the velocity, pressure, and temperature field becomes so strong that the NS and continuity equations
need to be solved together with the energy equation (the equation for heat transfer in fluids). The energy
equation predicts the temperature in the fluid, which is needed to compute its temperature-dependent material
properties.
Compressible flow can be laminar or turbulent. In the next example, we look at a high-speed turbulent gas
flow in a diffuser (a converging and diverging nozzle).
The diffuser is transonic in the sense that the flow at the inlet is subsonic, but due to the contraction and the
low outlet pressure, the flow accelerates and becomes sonic (M = 1) in the throat of the nozzle.

125
The results in these three plots show strong similarities, which confirm the strong coupling between the
velocity, pressure, and temperature fields. After a short region of supersonic flow (M > 1), a normal shock
wave brings the flow back to subsonic flow. This set-up has been studied in a number of experiments and
numerical simulations by M. Sajben et. al. [1-6].
What Flow Regimes Cannot Be Solved by the Navier-Stokes Equations?
The Navier-Stokes equations are only valid as long as the representative physical length scale of the system is
much larger than the mean free path of the molecules that make up the fluid. In that case, the fluid is referred
to as a continuum. The ratio of the mean free path, λ, and the representative length scale, L, is called the
Knudsen number, Kn=λ/L
The NS equations are valid for Kn<0.01. For 0.01<Kn<0.1, these equations can still be used, but they require
special boundary conditions. For Kn>0.1, they are not valid. At the ambient pressure of 1 atm – for instance,
the mean free path of air molecules – is 68 nanometers. The characteristic length of your model should
therefore be larger than 6.8 μm for the NS equations to be valid.
Finite Volume Method (FVM)
FVM is a discretization method for the approximation of a single or a system of partial differential
equations expressing the conservation, or balance, of one or more quantities. These partial
differential equations (PDEs) are often called conservation laws; they may be of different nature, e.g.
elliptic, parabolic or hyperbolic, and they are used as models in a wide number of fields, including
physics, biophysics, chemistry, image processing, finance, dynamic reliability. They describe the

126
relations between partial derivatives of unknown fields such as temperature, concentration, pressure,
molar fraction, density of electrons or probability density function, with respect to variables within
the domain (space, time,...) under consideration.
As in the finite element method, a mesh is constructed, which consists in a partition of the domain
where the space variable lives. The elements of the mesh are called control volumes. The integration
of the PDE over each control volume results in a balance equation. The set of balance equations is
then discretized with respect to a set of discrete unknowns. The main issue is the discretization of the
fluxes at the boundaries of each control volume: in order for the FVM to be efficient, the numerical
fluxes are generally
 conservative, i.e. the flux entering a control volume from its neighbour must be the opposite of the
one entering the neighbour from the control volume,
 consistent, i.e. the numerical flux of a regular function interpolation tends to the continuous flux as the
mesh size vanishes.
It is sometimes possible to discretize the fluxes at the boundaries of the control volume by the finite
difference method (FDM). In this case, the method has often been referred to as a finite difference
method or conservative finite difference method (see Samarskii 2001). The specificity of the FVM
with respect to the FDM is that the discretization is performed on the local balance equations, rather
than the PDE: the fluxes on boundaries of the control volumes are discretized, rather than the
continuous differential operator.
The resulting system of discrete equations depends on a discrete (finite) set of unknowns, and may
be either linear or non linear, depending on the original problem itself; this system is then solved
exactly or approximately, using for example direct or iterative solvers in the case of linear equations
and fixed point or Newton type methods in the case of nonlinear equations.

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APPENDIX 2
RESEARCH PROPOSAL
1. RESEARCH INTRODUCTION
With the increasing oil prices in earlier 20th
Century, requirement for more proficient performance, and efficient,
safer, ergonomic cars increased. Demand of the global greenhouse gas reduction has become one more significant factor
in the cars. This change leaded to tremendous brainstorm among car designers & manufacturers. This followed with the
significant questions regarding effect of shortage of the oil supply and the future of the automobile industry. Vivid
solutions were laid on the table which included the design of hybrid cars – electric & much more. Other proposed
approaches include the integration of air conditioning system with electronic devices to cut down energy consumption,
the redesign of car frame and body to reduce its total weight, and the modification of car external to improve the car
overall aerodynamic characteristics for better cruising conditions, greater stability of navigation, and lower energy
consumption. Feasibility of the solutions was given a second thought. The stage was turned on the focus on the
aerodynamics of car.
Aerodynamics for the cars has changed gradually from initial designers to the manufacturers’ to obtain more
power under the hood. This means more stability; better performance, better grip and most prominently increase the
Figure 1 showing the change of the drag coefficient along with years.

128
comfort of the car. People seem to have sportier look to have the best output performance. The 20th
century has seen
some of the finest sedan cars. From highest speed Hennessey Venom GT reaching up to 270.49 mph, Bugatti Veyron to
the luxurious Rolls Royce phantom and much more. Personal cars ranging from hatch backs, sedans & SUV have seen
major changes in their design and ergonomics depending on their customers’ choice. Aerodynamics plays a very crucial
role in increasing the fuel efficiency and safety of the driver. Efficiency of a car aerodynamically can be expressed by
coffieicient of drag denoted by CD while stability by CL coefficient of lift and is a dimensional less unit.
Fixing a rear spoiler at rear portion depends on shape of the rear portion whether the car is square back,
notchback or fastback because not all rear spoiler can be fixed at any type of rear portion of a car. However Rear spoiler
contributed some major aerodynamics factor which is lift and drag. The reduction of drag force can save fuel.
2. RESEARCH AIM
The aim of the research is to analyses how a rear spoiler helps in drag reduction by controlling the flow of the
air around the car body. The results obtained from the computational fluid dynamics (CFD) are validated and compared
to the model of a car designed as 2D surface in inventor with and without the spoiler.
3. RESEARCH OBJECTIVE
Understanding the drag coffieicient with the ground clearance, concepts of drag and lift in physics, pressure
distribution (Fundamentals of Physics, Resnick & Halliday), aerodynamic drag and lift acting on car, down force and
applying the above data on the model in designing and CFD to confirm the results. Using three different types of the rear
spoilers & their CFD analysis results to achieve the aim using following objectives in the research project:
 Analysis of the air flow around the car without the rear spoiler.

129
 Drawing out the possible outcomes comparing the results & establishing the relation of using rear spoilers for
better performance, reduced lift and drag.
4. RESEARCH LITERATURE REVIEW
Literature review should cover the basic standard principles of aerodynamics which is easy to be understood by
a layman. The equations are followed by the theory which focuses of the laws of physics and engineering of
aerodynamics governing the equations and results. This also includes the predominant theories and concepts used in the
project. Some of the concepts that will be discussed in brief in the literature review will be the following:
 Basic Drag & Lift concept along with their formulas.
,
 Understanding Bernoulli’s Equations for air flow over a moving object
Example of equations p + ½ ρ v2 + γ z = constant along streamline (Munson, 2006)
 Elaborate understanding of the aerodynamic for Drag & Lift forces.
 Pressure distribution across the surface of the car body.
 Understanding the down force.
 Coefficients of Drag and Lift CD & CL
 Applications of the above points on a rear spoiler of a model car.
Figure 2: showing Gillespie’s experiment results showing the effect of spoiler height to the aerodynamics of car.

130
5. RESEARCH METHODOLOGY
Followed by the literature review, would be the concept generation of the rear spoilers for the cars. A survey on
design of the aftermarket rear spoiler was done by surveying several spoiler designs in market that currently most used.
Because there several type of rear spoiler in market, so this step to ensure that the rear spoiler that will be used is most
used by car’s owner.
As the title reflects Aerodynamics of a car using rear spoiler, a series of the CAD files are generated of the
different types of spoilers. This also includes the design of the model car (Bugatti Veyron) with and without the rear
spoiler along with the spoilers. All the designs are generated on the Auto Desk Inventor 2014 as 2D surface. The designs
are exported as .iges or .step file to be extracted to the CFD package. ANSYS Fluent is used to run the models for
analysis. The CFD software interprets and results the value of CD & CL which is later explained in the observations &
calculations. The obtained results are explained and plotted on a graph. Every design of the spoilers is compared to the
base model.
Wind tunnel tests are generally quiet expensive and quiet time consuming. It takes weeks of through study, while the
same effects & results can be obtained on CFD ANSYS Fluent in hours.
PROJECT LIMITATIONS
One of the major limitations of the project was the system requirements. Most of the designs were generated and
simulated on computer with 4 GB of ram. This underscored and limited the designs to be in 2D surface models. As
making in 3D would consume more memory power and the lab was equipped with only above specification computers.
One of the major dependencies were the designs were generated on the Auto Desk inventor professional 2014. The
researcher has previous knowledge of using auto desk inventor instead of the designing geometry in ANSYS Fluent. This
consumed a major time as modifications and iterations based on the basic model, the researcher had to refer back to the
initial models in the CAD format in inventor.
Although the project started with a delay in analysis, much of the major time loss was a result of the initial
geometry design.

131
6. OBSERVATIONS & CALCULATIONS
The values are interpreted and plotted on the graph. The results of the model car without and with the rear
spoiler are compared. Every different design of spoilers is compared to the base design. The final results will compared
to prove the effect of rear spoilers in reducing aerodynamic drag, lift and coefficients of drag & lift enhancing the car
performance & safety in a tabular form
7. RESEARCH CONCLUSION
Finally finishing the report with conclusion along with the project Gantt chart, future works are also included to underpin
the potentials of the further research that could be extended by potential candidates.

132
RESEARCH ETHICS APPLICATION FORM
(STAGE 1)
More information on ethics procedures can be found on your faculty website. You must read the
Question Specific Advice for Stage 1 Research Ethics Approval form.
All research carried out by students and staff at Anglia Ruskin University and all students at our
Franchise Associate Colleges must comply with Anglia Ruskin University’s Research Ethics
Policy (students at other types of Associate College need to check requirements).
There is no distinction between undergraduate, taught masters, research degree students and staff
research.
All research projects, including pilot studies, must receive research ethical approval prior to
approaching participants and/or commencing data collection. Completion of this Research Ethics
Application Form (Stage 1) is mandatory for all research applications*. It should be completed by
the Principal Investigator in consultation with any co-researchers on the project, or the student in
consultation with his/her research project supervisor.
*For research only involving animals please complete the Animal Ethics Review Checklist instead
of this form.
All researchers should:
 Ensure they comply with any laws and associated Codes of Practice that may be applicable
to their area of research.
 Ensure their study meets with relevant Professional Codes of Conduct.
 Complete the relevant compulsory research ethics training.
 Refer to the Question Specific Advice for the Stage 1 Research Ethics Approval.
 Consult the Code of Practice for Applying for Ethical Approval at Anglia Ruskin University.
If you are still uncertain about the answer to any question please speak to your Dissertation
Supervisor/Supervisor, Faculty Research Ethics Panel (FREP) Chair or the Departmental
Research Ethics Panel (DREP) Chair.
Researchers are advised that projects carrying higher levels of ethical risk will:
 require the researchers to provide more justification for their research, and more
detail of the intended methods to be employed;
 be subject to greater levels of scrutiny;
 require a longer period to review.
Researchers are strongly advised to consider this in the planning phase of their research
projects.

133
Section 1: RESEARCHER AND PROJECT DETAILS
Researcher details:
Name(s): Dibyajyoti Laha
Department: Engineering & Built Environment (Mechanical Engineering)
Faculty: Science &Technology
Anglia Ruskin email address: dl411@student.anglia.ac.uk
Status:
Undergraduate X Taught
Postgraduate
Postgraduate
Research
Staff
If this is a student project:
SID: 1227201
Course title: BEng Mechanical Engineering Honors
Supervisor/tutor name Dr. Ahad Ramezanpour
Project details:
Project title (not module title): “Computational aerodynamic analysis of a rear spoiler on
a car in two dimensions“
Data collection start date:
(note must be prospective)
1 st March 2015
Expected project completion date: 8th
May 2015
Is the project externally funded? No
License number (if applicable): No
CONFIRMATION STATEMENTS – please tick the box to confirm you understand these
requirements
The project has a direct benefit to society and/or improves knowledge and understanding. X
All researchers involved have completed relevant training in research ethics, and consulted
the Code of Practice for Applying for Ethical Approval at Anglia Ruskin University.
X
The risks participants, colleagues or the researchers may be exposed to have been considered
and appropriate steps to reduce any risks identified taken (risk assessment(s) must be
completed if applicable, available at: http://rm.anglia.ac.uk/extlogin.asp) or the equivalent
for Associate Colleges.
X
My research will comply with the Data Protection Act (1998) and/or data protection laws of
the country I am carrying the research out in, as applicable. For further advice please refer to
the Question Specific Advice for the Stage 1 Research Ethics Approval.
X
Project summary (maximum 500 words):
Please outline rationale for the research, the project aim, the research questions, research
procedure and details of the participant population and how they will be recruited.
Socio-economic factors have changed with the recent years. Hikes in fuel price (BP, histogram data, 2012) and
desperate need to reduce the greenhouse gas emissions have increased since 1970 (Reuters, 1970). This has leaded the
automobile industry to rethink on their product’s efficiency, ergonomics and safety. Studies and research came up with
varied solutions like electric car or hybrid cars (Tesla Motors, 2002). Among them was rethinking and designing of the
automobiles. Aerodynamics plays a very crucial role in increasing the fuel efficiency and safety of the driver. Efficiency
of a car aerodynamically can be expressed by coffieicient of drag denoted by CD while stability by CL coefficient of lift

134
and is a dimensional less unit
With the recent drop in the drag coefficient and use of more conventional methods based on the aftermarket of the cars
have increased. These methods include the regulation of the air flow around the vehicle to increase stability while driving
at higher speed and reduce drag coefficient. Rear car spoilers are one of the devices that are designed to ‘spoil’
unfavorable air movement across a car body. Fixing a rear spoiler at rear portion depends on shape of the rear portion
whether the car is square back, notchback or fastback because not all rear spoiler can be fixed at any type of rear portion
of a car. However Rear spoiler contributed some major aerodynamics factor which is lift and drag. The reduction of drag
force can save fuel.
Aim: The aim of the research is to analyses how a rear spoiler helps in drag reduction by controlling the flow of the air
around the car body. The results obtained from the computational fluid dynamics (CFD) are validated and compared to
the model of a car designed as 2D surface in inventor with and without the spoiler.
Objective: The research focuses on the basic concepts of the aerodynamics acting on the car. This includes David
Bernoulli’s equations to understand the effect of the flow of the air around a body in motion (Glenn Research Centre,
NASA, 2014). Understanding the drag coffieicient with the ground clearance, concepts of drag and lift in physics,
pressure distribution (Fundamentals of Physics, Resnick & Halliday), aerodynamic drag and lift acting on car, down
force and applying the above data on the model in designing and CFD to confirm the results. Using three different types
of the rear spoilers & their CFD analysis results to achieve the aim using following objectives in the research project.
 Analysis of the air flow around the car without the rear spoiler.
 Drawing out the possible outcomes comparing the results & establishing the relation of using rear spoilers for
better performance, reduced lift and drag.
Methodology: Thorough study of the spoilers available in the market is done to apply at least 3 different models of the
spoilers on the rear of the car and analyses the data on the CFD software package. Definite meshing and geometry
conditions are assigned along with the domains to find the drag coefficient value from ANSYS Fluent (CFD software).
The values are interpreted and plotted on the graph. The results of the model car without and with the rear spoiler are
compared. Every different design of spoilers is compared to the base design.
Expected Results: The final results will compared to prove the effect of rear spoilers in reducing aerodynamic drag, lift
and coefficients of drag & lift enhancing the car performance & safety in a tabular form.
Section 2: RESEARCH ETHICS CHECKLIST - please answer YES or NO to ALL of the
questions below.
WILL YOUR RESEARCH STUDY? YES NO

135
1 Involve any external organisation for which separate research ethics clearance is
required (e.g. NHS, Social Services, Ministry of Justice)?
X
2 Involve individuals aged 16 years of age and over who lack capacity to consent
and will therefore fall under the Mental Capacity Act (2005)?
X
3 Collect, use or store any human tissue/DNA including but not limited to serum,
plasma, organs, saliva, urine, hairs and nails? Contact
matt.bristow@anglia.ac.uk
X
4 Involve medical research with humans, including clinical trials? X
5 Administer drugs, placebos or other substances (e.g. food substances, vitamins)
to human participants?
X
6 Cause (or could cause) pain, physical or psychological harm or negative
consequences to human participants?
X
7 Involve the researchers and/or participants in the potential disclosure of any
information relating to illegal activities; or observation/handling/storage of
material which may be illegal?
X
8 With respect to human participants or stakeholders, involve any deliberate
deception, covert data collection or data collection without informed consent?
X
9 Involve interventions with children and young people under 16 years of age? X
10 Relate to military sites, personnel, equipment, or the defence industry? X
11 Risk damage or disturbance to culturally, spiritually or historically significant
artefacts or places, or human remains?
X
12 Involve genetic modification, or use of genetically modified organisms above
that of routine class one activities?
Contact FST-Biologicalsafety.GMO@anglia.ac.uk
(All class one activities must be described in Section 4).
X
13 Contain elements you (or members of your team) are not trained to conduct? X
14 Potentially reveal incidental findings related to human participant health status? X
15 Present a risk of compromising the anonymity or confidentiality of personal,
sensitive or confidential information provided by human participants and/or
organisations?
X
16 Involve colleagues, students, employees, business contacts or other individuals
whose response may be influenced by your power or relationship with them?
X
17 Require the co-operation of a gatekeeper for initial access to the human
participants (e.g. pupils/students, self-help groups, nursing home residents,
business, charity, museum, government department, international agency)?
X
18 Offer financial or other incentives to human participants? X
19 Take place outside of the country in which your campus is located, in full or in
part?
X
20 Cause a negative impact on the environment (over and above that of normal
daily activity)?
X
21 Involve direct and/or indirect contact with human participants? X

136
22 Raise any other ethical concerns not covered in this checklist? X
Section 3: APPROVAL PROCESS
Prior to application:
1. Researcher / student / project tutor completes ethics training .
2. Lead researcher / student completes Stage 1 Research Ethics Application form in consultation with co-
researchers / project tutor.
NO answered to all questions
(Risk category 1)
(STAGE 1 APPROVAL)
NO answered to question 1-13
YES answered to any question 14-
22 (Risk Category 2)
(STAGE 2 APPROVAL)
Yes answered to any question 3-13
(Risk Category 3B)
Research can proceed.
Send this completed form to your relevant
DREP for their records.
i) Complete Section 4 of this form.
ii) ii) Produce Participant Information
Sheet (PIS) and Participant Consent
Form (PCF) if applicable.
iii) Submit this form and PIS/ PCF where
applicable to your Faculty DREP (where
available) or Faculty FREP.
Two members of the DREP/FREP will review
the application and report to the panel, who
will consider whether the ethical risks have
been managed appropriately.
• Yes : DREP / FREP inform research
team of approval and forward forms
to FREP for recording.
• No: DREP / FREP provides feedback to
researcher outlining revisions
required.
The panel may recommend that the project is
upgraded to Category 3 - please see below for
procedure.
Complete this form and the Stage 2 Research
Ethics Application form and submit to your
FREP. FREP will review the application and
approve the application when they are
Yes answered to question 1 and /
or 2
(Risk Category 3A)
Submit this completed form to your FREP to
inform them of your intention to apply to an
external review panel for your project.
For NHS (NRES) applications, the FREP Chair
would normally act as sponsor / co-sponsor for
your application.
The outcome notification from the external
review panel should be forwarded to FREP for
recording.

137
Section 4: ETHICAL RISK (Risk category 2 projects only)
Management of Ethical Risk (Q14-22)
For each question 14-22 ticked ‘yes’, please outline how you will manage the ethical risk posed by
your study.
Section 5: Declaration
*Student/Staff Declaration
By sending this form from My Anglia e-mail account I confirm that I will undertake this project
as detailed above. I understand that I must abide by the terms of this approval and that I may not
substantially amend the project without further approval.
**Supervisor Declaration
By sending this form from My Anglia e-mail account I confirm that I will undertake to supervise
this project as detailed above.
*Students to forward completed form to their Dissertation Supervisor/Supervisor.
** Dissertation Supervisor/Supervisor to forward the completed form to the relevant ethics
committee.
Date: August 2014
V 5.2

138
CV, Cover Letter and Exit Plan

CV - Dibyajyoti Laha
G.P.A. 1st Year : 3.38/4.0 120 Credits Completed.
G.P.A. 2nd
Year: 3.86/4.0 120 Credits Completed
Dibyajyoti Laha
Flat above no 8., 10 B Broomfield Road. Chelmsford
Essex, England, U.K. CM1 1SN
M (+44 074 638 98808) Email : dlaha.cloud@hotmail.co.uk
CAREER OBJECTIVE
Seeking opportunities in Mechanical/ Manufacturing Engineering (Specialize in Design, Production, Procurement & Management)
AngliaRuskinUniversity, Chelmsford, England, U.K. Course:
EDUCATION Institutes:
BEng Mechanical Engineering Honours. (Pursuing 3rd Year) Date of completion:
Expected 30th May 2015.
Foundation: ManipalUniversity &KurukshetraUniversity, India
Course : BE Mechanical Engineering (A Levels and Foundation respectively)
Percentage: 74.5%
> Mathematics 1 & 2
RELEVANT COURSEWORK
> Mechatronics > Manufacturing
> Applied Mechanics > Engineering Materials > Statics & Dynamics
> Fluid Mechanics > Thermodynamics > CAM & Auto CAD
> Heat Transfers > Applied Software > Process Quality
> Technology Projects > Environmental Sciences > Engineering Physics 1&2
> Modelling and Simulation for Operation Management > CAE Ansys Workbench > Engineering Management.
> Stress & Dyanmics > Learning skills for HR & work
> Thermofluids.
ENGINEERING INTERNSHIPS / WORK EXPERIENCES
2007- NASA-ISSFinternship,JohnsonSpaceCentre, Houston, Texas, U.S.A.
Position: Aerospace Design Intern (Engineering)
Brief : Used AutoCAD to design rovers and parachute systems in the rocketry. Made 2D drawings for the
mission and presented powerpoint presentations of the project. The project was declared successful with a
graduation certificate from Astronaut Nicole P Scott in association with Jet Propulsion Laboratory. Networking
and teamwork were a major part of the internship program along with management roles in the project.
2010 - ThyssenKruppEngineering, Germany.
Position: Mechanical/ Constructional Engineering
Brief : Internship with ThyssenKrupp was more focused with the Deputy Site Manager. Performed surveys
on material engineering, procurement and production line of a large scale refinery plant along with
Engineering management in industry. Design of the prototypes and run descriptions. Lean Manufacturing skills
Like SPC, SPOIC, Lean factors, KANBAN
2011 - AdityaBirlaEngineeringLtd. India, Mumbai, India
Position: Mechanical / Built Construction Engineering (ALUMINIUM production unit)
Brief : Solved engineering problems on designs analysis, Gained exceptional problem solving, communication
leadership and interpersonal skills. Faced actual customer projects and real time responsibility.
Design Analysis, engineering sales, (for details on project please refer my linkedin account)
November 2013 - HewlettPackard(HPMicrosoft-CPM). Essex, UK,
Position : HP - Microsoft training and office products analyst at Currys PC World. Increase microsoft software
awareness.

Nov 2013 - January 2014 SONYElectronics,UK.Essex.
Worked as Sony’s business analyst for home theatre systems and television technology at
Currys PC World. Engineering Sales, audits, head office compliances and
January 2014 - Till date VAXUK– TTIFloorCareNorthAmerica.Essex
Description:
VAX - TTI Floorcare North America are currently the No 1 best-selling floorcare brand in the UK. With a rich
heritage and growing global position, we are a market-leader in floorcare innovation. Not only that, Vax is one of
The Sunday Times Top 100 Best Companies To Work For 2014 and the only floor care equipment manufacturer
business on the list!
Vax Commercial is fast becoming a highly respected and revered brand within the Commercial / Professional
sector in the UK, achieving phenomenal growth in the last year with the introduction of new products & industry
leading marketing campaigns.
The role
An excellent opportunity in commercial team to support the Commercial and Engineering sales function with
new and on-going projects and all associated activities appropriate to major accounts and building relationships
with major accounts’ key personnel. Engaging heavily with the sales team in store and be involved in the
effective running of the team day to day. This role is varied and offers a breadth of exposure to commercial areas
in the business.
Responsibilities will include:
Day to day account activity
Management of new and on-going projects and product launching
Processing product samples of in-warehouse products and maintaining sample log
Documentation, origination and co-ordination of sales and marketing data
Problem solving at customer interface with major accounts
Presentation support – including key account materials and analysis, manipulation and graphic representation of
market data
Assisting in organisation and preparation for exhibitions, trade shows and displays for major accounts
Maintenance and production analysis.
Product demonstration, training, auditng, Merchandising & aggressive marketing the new designed products for
VAX one of the TTI companies. Demonstrations, audits and feedback to HQ.
June 2014 – Till date Eppendorf CryoTech UK. (A subdivision of Eppendorf AG, Hamburg Germany)
Company background
Eppendorf CryoTech, Maldon, UK, is part of a group of leading life science companies that develops and sells
instruments, consumables, and services for liquid-, sample-, and cell handling in laboratories worldwide.
Products are most broadly used in academic and commercial research laboratories, e.g., in companies from the
pharmaceutical and biotechnological as well as the chemical and food industries. They are also aimed at clinical
and environmental analysis laboratories, forensics, and at industrial laboratories performing process analysis,
production, and quality assurance.
The company specializes in the design and manufacture of ultra-low temperature freezer products, which are
distributed world-wide.
Project details
Working with the manufacturing area manager and supervisors to assist in the data collection and analysis of the

assembly steps from receipt of component parts through the sub-assembly stages to final
assembly, finished product test, product clean and pack, ready to ship to finished product
warehouse for subzero temperature freezers.
Assisting with generating simple data collection documentation templates to assist in the effective
collection of work center efficiency data, and involved in the analysis of data and in the review and
recommendations for reduction in waste and efficiency improvements.
Development Focus
Eppendorf CryoTech, Eppendorf AG hopes to significantly improve the efficiencies in their
manufacturing process and reduce their waste in materials. Also to gain production data,
introduce standards and optimise production time. Therefore, this is an excellent opportunity to
really make a difference at this very busy time. Getting strong hands on experience in an
engineering/manufacturing environment.
March 2015 - Till date Computational aerodynamic analysis of a rear spoiler on a car in two dimensions:
Anglia Ruskin University.
It included the design of the model car BMW 3series and analyze the air flow around the body in
2D.
Apart from designing it included the use of ANSYS CFD tool to study the air flow.
March 2015 – Till date Nespresso
Nestle – UK
Field Sales
Engineering
Core brand team of over 140 permanent executives throughout the UK & Ireland Created an industry
leading reporting app that centralizes working schedules, GPS tracking to monitor
compliance, sales reporting tools and incentivized training modules to further
develop brand knowledge Nespresso’s exclusive consumer facing app enables
consumers to order coffee and sign up to the Nespresso’s Club at point of purchase
A tailor made recruitment and induction program that
Includes a 2 day training schedule for all new starters and refresher courses for existing
demonstrators Designed a bespoke, premium uniform to create stand out in-store Delivery
of experiential events in shopping centers across the UK
Additional Experience: AngliaRuskinManufacturingWorkshop: Construction of working hot air engine, machining,
assembly AngliaRuskinSoftwareDevelopment: Coded and worked on CNC machines
software and development. CPMUnitedKingdom&ChannelAdvantageUK : Performed
management operational duties across Essex.
CPMUnitedKingdom,HPCampaigns: Event manager at HP campaigns at PC Currys world
across Basildon, Essex. .
MASHStaffingUnitedKingdom: Worked as manager for momentum ASDA Harlow for Halloween.
Invited Student Experience: GoldmanSachs. London, United Kingdom. 2013
Invited to experience the culture of the organization and the working of technology infrastructure
TECHNICA
L SKILLS
> Project management > SAP manufacturing ERP > Solid Edge >Solid works
> Health and Safety training. > Welding Process & Theory > Designing > Rapid
> Lathe Machining & CNC operations > Metal Fabrication > Milling > Basic Hand tools
> Microsoft Office > KANBAN (JIT) > Operating Systems (Mac., Microsoft > C, C#, C++ &
> Adobe > Safety Handouts > Sig Sigma Belt for Manufacturing

HONOURS
● 9th position in International Science Olympiad
(Gold medal)
● High School Secretary
CERTIFICATES
● Safety & Health in Construction (Irish Certificate)
● Diploma in Fine Arts & Painting
● Diploma in Workplace Safety & Health
● Diploma in Project Management.
● Diploma in Human Resource Management.
PERSONAL STATEMENT
Born and raised in the family of an engineer. Throughout high school and college, my father a construction mechanical engineer has been an
ideal person for me. At school I was fascinated about aerospace and spent a year as a design intern at NASA, grew up as teenager with interest
in oil and gas in mechanical, did welding, milling, casting, forming in a small workshop. In the summers of high school worked as intern in
ThyssenKrupp India, analysed the designs of lifts, constructions, designs to development of a product. In nut mechanics and its engineering
runs in my veins. I am an inquisitive person by nature and like to learn more.
MEMBERSHIPS
● Student Member of IET (Institute of Engineering & Technology)
● Student Member of CIOB, UK (Chartered Institute of Building)
● Permanent member of IAC, France (International Aeronautical Congress)
● Alumni of NASA - ISSF, Texas, U.S. (International Space School Foundation)
● Member of SAE International.
REFERENCES
Dr. Ahad Ramezanpour (Academic)
Mr. Dilip Kumar Laha. D.S.M. Jacobs Engineering India (Colleague)
Dr. Mathias Schumann (Professional)
Available upon request
SOCIAL NETWORK
Linkedin: uk.linkedin.com/pub/dibyajyoti-laha/54/303/122
Skype : Netmash.inc

1Dibyajyoti Laha Exit Plan
Future Aspects
Exit Plan
Thermofluids
(MOD002684)
This module gave a theoritical approach to the study of thermodynamics but, at the same time it is a very
practical subject to understand fluids and heat laws.Studying this module enabled me to grasp a better
understanding of the following topics :
 · First law of thermodynamics
 · Properties of liquid and vapor, properties of gas
 · Second law of thermodynamics
 · Reciprocating air standard cycles
 · Chemical reactions, combustion
 · Fundamentals of heat transfer
 · Combined heat transfer modes
 · Fundamental of fluid mechanics, fluid statics
 · Fluid dynamics, steady flow process and momentum equation
 · Steady flow energy equation, dimensional analysis
Apart from the standard theoritical concepts, the final assignment for this module dealt with the Air
re-circulation inside a freezer, which focused on the application of a software ANSYS CFD (Computational
Fluid Dynamics) & EnSight 10.1 to understand a products thermodynamic behavior.
Learning Outcome
Looking for future in mechanical Engineering this module will play an active role . I personally look forward to
work in Oil & Gas production, where this module would play a very active role.
Materials and Processes
(MOD002634)
The module is a legitimate approach towards better understanding of the composite engineering and
important aspects of engineering materials if as mechanical engineer, the candidate wants to per-sue his
career in the field of process engineer or design engineer. The module course outlined the study on the
following topics and is an advanced level of the module Introduction to Engineering Materials
 Behavior of engineering material under stress.
 Effects of heat on materials, heat treatment of engineering materials and phase diagrams
 Stress concentration and finite element analysis
 Fatigue
 Creep
 Stress corrosion
 Corrosion and degradation
 Principles of composite design and applications
 Economics of manufacture processes
 Effects of manufacturing method on material properties including grain flow, residual stresses, etc
 Manufacturing processes including casting, forging, pressing, welding
 Re-cycling of materials
Learning Outcome

Future Aspects
Apart form the standard theoritical knowledge, the module gave market experience about the studies with
two iconic industrial visits to leading composite material manufacturing companies - Encocam UK Ltd & an
American company - TruckLite. The module encouraged visiting lecturers and guest speakers on the
application and broader spectrum
Introduction to Engineering
Materials (MOD002565)
This module improved the basic regarding to structure and properties of a range of engineering materials. It
also improved the knowledge about laboratory work where tensile tests were done for different materials in
different experiments
 Atomic configuration of metals and non metals
 Bonding in metallic and non metallic materials
 Simple concepts of alloying
 Single and binary alloy systems
 Equilibrium and non equilibrium transformations.
 Precipitation alloys
 Electronic structures of insulators ,semi conductors and conductors with reference to energy gap
 Valency band and conduction band
 Structure and application of polymeric materials
Learning Outcome
Future Aspects
The module is a pre requisite for the module Materials and Process. This module not only enhances the basic
understanding of material science and properties but also gives a standard idea of the industrial tests which
would be needed in the future or while at job.
Mathematics for Engineering
(Year 1 & 2) (MOD003214 ,
MOD002306)
The modules included the standard mathematics for engineering touching and explaining the theoritical
mathematics.
Learning Outcome
Matrices, Integration, differentiation, Basic geometry maths, applied mathematics and statics probability.
Along side in the module for Maths in year 2 focused on the more vital aspects of the hand in calculation of
the differentiation and integration, Lagrangian formula, Taylor series, Fourier series and heat maths and
probability. Statistics in the construction industry, linear regression, Normal distribution, Determinants,
Matrices. In fine, it was really an important module to solve difficult problems regarding to engineering
calculations.
Future Aspects
The module gives a better understanding in the everyday technology maths. Applications involve in plenty of
the subjects like Thermofluids (standard 2nd order differentiation, Double integration for heat and work
calculation, using the matrix based formulas on FEA analysis ) and much more.
Mechatronics
(MOD002584)
A combination of two disciplines : mechanical and electrical. A always demanded module for an overall
understanding of electrical and mechanical products.

Future Aspects
Future Aspects
Learning Outcome
In mechanical part, it was all about mechanical behavior and its calculation on pulley, gears, cam, bulb etc. On
the other hand, electrical part was about electrical components description and calculation as well as it
helped to teach the using of software called Multisim which can be used to draw circuit connection and to
observe the behavior of resistor, voltage, current etc. by changing some components inside the circuit
connection like, diode.
Future Aspects
This module can play an active role in the future specific job roles like automation and production engineers
where constant communication is needed between the electrical parts and the mechanical products like gear
box in a car and the dash board display.
Applied Software
(MOD002561)
Module based on the basic understanding and practical application of coding any software using C and C++
Learning Outcome
Applied software focused on the learning of the basic programming language called C. This included on the
programming for basic and complex. The assignment included designing a ticket vending machine based on
the platform of C. In nut this module gave on additional experience to the mechanical engineers to have
practical experience on coding.
With the knowledge of this module, it would be easy for mechanical engineers to code software or platform
for any opertions related to computer performance . Fopr example using a CNC machine.
Manufacturing
(MOD002554)
The module manufacturing focused on the understanding of the manufacturing world. This included the
simple steps and process involved for the product to come to market from the raw/ initial stage.
Learning Outcome
Manufacturing module taught to design and work in a workshop with machines like CNC machine and Lathe.
Other applications of the study included the basic foundry shop applications like moulding, casting and hand
axes and trimming, filing. It was a first module which helped to teach how a group work is important and how
to work in a group.
This module provided a broad spectrum of the knowledge required for the production - mechanical
manufacturing companies.
Engineering Principles
(MOD003120)
An more elaborate module on better understanding of the year 1 Mechatronics.
Learning Outcome
The electrical section consisted of the resistor, inductor, capacitor, voltage and current relationships in dc
and ac circuits and Kirchhoff’s laws relating to dc and ac circuits and thevenin. The mechanical discipline dealt
with the calculation of forces, velocity, acceleration, distance, moments. The assignment consisted on the
theoritical research in a summarized set of questions based on the practical experience in the laboratory too.

Future Aspects
Future Aspects
Future Aspects More understanding on the subject of statics and Dynamics of bodies in applied mechanics
Statistics and Process
Quality Assurance
(MOD002607)
A module designed to deliver the potentials of running a Quality control in an organization, understanding the
need and techniques invloved in it.
Learning Outcome · Understanding the Quality management systems and standards e.g. ISO 9000. & ISO 140001
· Improving the technical and non technical quality technique including Pareto, cause and effect diagrams,
Shew cycle, etc.
· Probability and statistics including: sampling, graphical representation of data, regression, binomial, Poisson
and normal distributions, measures of location and spread, expected values hypothesis testing, correlation.
· The role of inspection including costs and risks.
· Constructing & interpreting statistical process control charts including the following types: attribute,
average and range, average and standard deviation, moving average/moving range, multi-stream .
· Assessment of process capability and calculation of expected reject rates.
· The module will also give an appreciation of the wider aspects of quality management that are vital to the
survival of all organizations
· Understand the function and importance of quality assurance in the organization and management of a
company.
The module is an important course in the field of engineering as well as in non technical. This module helps in
understanding how to improve the profitability and meeting quality standards.
Applied Mechanics
(MOD002616)
It was a study of the statics and dynamics of particles and rigid bodies under the influence of forces. It can be
said that this module was proper physics. This module mainly dealt with shear force for simple beams and
bending moments including analysis of simple stress cases with shear and normal stress.
Learning Outcome
Understanding Pin joint forces, Dry friction motion on horizontal and inclined plane, Shear force and bending
moment diagrams; simply supported and cantilever beams. Better understanding of the Mechanisms; velocity
diagrams, four bar chains reciprocating mechanisms, Static And Dynamics of fluids concept of head;
Bernoulli equation, flow through pipes venture meter an dynamics
Applied Mechanics is a module which focuses on the knowledge of the structural mechanics, understanding
the construction forces. This is an ideal subject for mechanical construction or field based mechanical jobs.

Learning Outcome
Future Aspects
Computer-Aided Solid
Modelling (MOD002610)
As the name says, this module was an interactive approach and assessment based course which developed
the skills of designing any 3D product on 2D and generate the 3D structure of it.
This module focused on the use of the software Auto Desk inventor professional for designing the product.
Basic 2D sketches, Basic applications of assembling multiple parts, extrusion, filing and riveting designs.
Future Aspects
This module helped to design my own product for the assessment " A kid's scooter" . Even this module
helped to generate product for CAE analysis and CAM . In nut the module provided an interactive
approach to build and design own products.
CAE (Computer Aided
Engineering) (MOD002656)
One of the finest and most demanded subject, CAE plays an active role in shaping engineering products. CAE
offers an interactive software learning used in commercial industry.
Use of ANSYS Workbench 15.
Product research
Analysis of the static stress
Application of effects of stress
Generating CAM code for the physical product production in workshop
Comparisons of the physical part test and ANSYS Workbench results
Learning Outcome
CAE as a module can be used in FEA (Finite Element Analysis) industry, product development. Further studies
of CAE can include subjects like AEROSPACE - NASA (nastran) and much more in everyday engineering. -
Stress & Dynamics
(MOD002668)
A subject focused on the theoritical knowledge of the application of stress and vibrations on moving objects.
Learning Outcome Vibrations
Stress & Dynamics of the moving and static objects
Basic understanding of the laws and second order differentiation
Spring formulas and example
Design of the paper straw bridge.
Future Aspects The further prospects of this module is to gain more wide application in engineering construction.
Modelling & Simulation for
Operations Management
(MOD002665)
A subject which is a non technical aspect but helps engineering in determining profit, costs, labor and
budgeting

Future Aspects
Learning Outcome Operational issues
Manufacturing Industry application of Modelling and Simulation.
Description in flow chart
Generating model
Running model and find best possible outcomes.
Future Aspects
The module can help engineering to run softwares for budgeting and running profit. The wide applications
include softwares like info32, LN Info which records and makes modelling and simulations easy. Other
software includes SAP ERP
Project Management for
Technologists
(MOD002666)
A non technical subject focused more on the applications of HR and management strategies to be learnt at
university level. The subject focused on the engineering management point to increase efficiency of an
organization.
Planning & Control of projects
Operational research techniques
Use of Microsoft Project
Generating budgets
Learning Outcome
Future Aspects
As a future role this module can be helpful to be a part of engineering management decisions in real life
industry.
Research Methods &
Individual projects for
Mechanical Engineering
(MOD002387)
This module is focused on generating a piece of research report for undergraduate thesis.
To generate literature review
Present and conduct a research with a supervisor
Generate a piece of research (academic report) of 10,000 word that included the 2d study of the car rear
spoiler aerodynamics by the use of ANSYS CFD tool.
Learning Outcome
This module allows the students to understand the format of IET based report writing and conduct similar
reports while in actual engineering jobs.
Group Design Project
(MOD002309)
A module that encouraged team work and application of research ideas in engineering field. The module also
helped students to understand of selecting, conducting and soluting a research project.
Feasibility of a project
Selection of project
Market Research
Pugh Chart
Learning Outcome

Research report
Use of chart based selection methods
Presentations & patenting individual research
Future Aspects Future applications include real life understanding of selecting a project
Learning & Skills
Development for HE & Work
(MOD002579)
A non technical module similar to Project Management. It focused more on application of different
organization skills, encourage use of internet and blogging, better understanding of a difference between an
essay and technical report as well as an academic report.
Understanding report writing
understanding copyright
Internet & Blogging
Presentation
report and plagiarism
Learning Outcome
Future Aspects This module gave an introspect how to write an academic report, referencing and help to curb plagiarism
With the complete 3 years of the study, the modules have enabled me to get a better and dynamic picture of the Engineering
world and look forward to implement the broader ideas studied or gained from these modules in the organization I look to join.
Its a dream come true and a start to a proper full time professional mechanical engineering career.

To,
The recruitment Agency
Dear Sir/ Madam
Subject: Actively looking for Engineering roles in Production/ Mechanical Engineering/ Design
Engineering in DONG Energy.
I am Dibyajyoti Laha, an international undergraduate student from India in Mechanical Engineering at
Anglia Ruskin University. I have recently finished my 2nd year in Mechanical Engineering with 1st
division scores in core subjects of Mechanical Engineering. I come from an engineering background.
My engineering course of mechanical engineering undergraduate at Anglia Ruskin consists of modules:
Thermodynamics, Fluid Mechanics, Environmental science, Heat transfers and manufacturing
engineering, Engineering Mathematics and flow chart design for process, Data analysis. I am humble to
say that I finished my GSC with 86.5 % in STEM and Foundation in BS Mechanical with 74.5%
I started growing my interests in manufacturing industries since the age of 15. Alongside studying in my
GSC levels I applied for internship with NASA - JPL (National Aeronautics & Space Administration in
collaboration with Jet Propulsion Laboratory) based in Houston, Texas, US. I spent an extensive couple of
months in practising and designing rovers to be sent to Mars by NASA for research projects. My skills
enhanced in aerospace designs and tailored/ customer engineering including generating designs on
Inventor, test runs and model demonstrations along with propulsion systems. Simultaneously I had
presented the project with my team to an astronaut Nicole P Scott, who was our supervisor and received
a graduation certificate with the completion of the mission. Quiet acquainted with Engineering
manufacturing, I followed up in a tradition of gaining more work experiences. My project with
ThyssenKrupp Engineering Germany was in manufacturing gave me ample experience in the design
generation, market analysis, use of the structural analysis and successful run of the test products on
AutoCAD for analysis. I again spent time in an Indian MNC brand Aditya Birla, based in Mumbai India. This
gave me hands on experience in skills involving procurement, management, and application of 6 sigma
techniques. I also gained experience with, batch production, mat lab and computer aided manufacturing.
While studying in the UK I decided to gain experience with the market of England. I joined one of the
largest global work forces sales and marketing company’s CPM where I was involved in consumer
product analysis, training, feedback and complaints with the HQ, following up I wanted to practice more
in the core engineering sector. Sony UK was an opportunity to work closely with the sales and
engineering experiences but due to restriction of contract I had to switch to VAX UK where I am presently
working part time with Curry’s Colchester in training and development of the products, demonstrations,
consumer awareness and design analysis. Use of Microsoft office for data predictions and collection,
spread sheet, work and access were involved in work reporting.
I decided to opt for mechanical engineering as a core sector to achieve my aspirations in manufacturing
and design. I recently studied and made live practice in subjects like Materials and Process, Engineering
design and Analysis, Human factors in Ergonomics, Industrial process quality and control and
mechatronics. My 2nd year research project at university on Hydrogen Gas Turbine was well appreciated
by Siemens Energy UK student research which can be found on slide share along with my other projects.
For the last 6 months I have been working as a Production Optimisation Engineer intern(first 3 months)
and production engineer (presently) at Eppendorf CryoTech UK, a part of Eppendorf AG. The placement
has been an ideal dream job. From day to day timing, optimising with lean techniques, Kaizen methods for
efficient production, the placement has amazed me with the potentials involved working with Eppendorf.
I am finishing my university course with an honours degree in 2:1 by May 2015. I am a hardworking and
ambitious Engineering undergraduate, who is a team player with excellent time management skills. I am
intellectually curious and a quick learner and would love to have the opportunity to extend my
experience by working with the Organization.
Sincerest Regards
Dibyajyoti Laha

ANSYS Fluent - CFD Final year thesis

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