CFD Lecture (1/8): ZNTutor CFD- An Introduction

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ZNTutor-CFD: An Introduction
Freeware CFD Software for learning the basics of CFD
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©ZeusNumerixPvtLtd:ConfidentialDocument
Overview of Presentation
 Philosophy
 Wizard mode
 1D Shock tube problem
 Converging-Diverging Nozzle
 Interactive mode
 Flow over a ramp
 Analysis
16 June 2020 Introduction to ZNTutor-CFD: Zeus Numerix Training Software
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Philosophy
 ZNTutor-CFD™ is aimed at introducing students and beginner engineers to CFD
 It serves as a virtual fluid mechanics lab
 The purpose is to give a feel of CFD but not solving industrial problems
 It takes you through the whole CFD process
 You can download your free copy from www.zeusnumerix.com
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The Two Modes
 Wizard Mode
 Pre-defined problems from fluid mechanics textbooks
 Problems can be solved in few minutes
 At all steps, guidance is given to the user
 Interactive Mode
 Learn to define a problem
 Make new geometries for simulation
 Inbuilt geometric modeler and post-processor
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Wizard mode
Functioning of wizard mode
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Wizard Mode: GUI
Menu Bar
Problem stage
Problem selection
Commands and feedback line
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1D Shock Tube Problem
 Shock tube problem is defined as sudden change of properties in space
 Define Numerical Schemes – to inform participants about the merits and demerits of
each scheme
 Select Solver Control – define the domain, CFL, time step
 Define Initial Condition – Physical properties like pressure, density, velocity
 View Solution – shows the actual solution in red and the simulation result in green
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GUI
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Result: Analytical & Computed
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2D wizard
Example problem in 2D wizard
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The 2D Wizard
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The 2D Wizard
 Define problem – choose from a list of problems
 Define geometry – the menu gives a description of geometry and in some cases
parameters can be changed
 Define grid – problems give choice of structured and unstructured grid
 Select solver control – choose solution algorithm, accuracy etc
 Define flow condition – supply the flow conditions at which the problem is to be
solved
 View solution – choose initial conditions, number of iterations, time marching etc
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Final Grid
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Solution
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Interactive mode
To define and solve a problem in interactive mode
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Problem Definition
 Problem definition has to be thought of by user and then appropriate tools must be
chosen to create geometry
 Here we chose flow over an inclined ramp
 Figure show the problem statement
 Expected an oblique shock on the ramp
Supersonic
inflow
Outflow
1 m
0.3 m
0.5 m
0.04 m
0.36 m
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Creation of Topology & Grid
 Create a domain
 Menu Grid2D Structured Create Init Block
 Input X = 1.0 and Y=0.4
 Divide the block in three parts
 Grid2D Structured Create Input Values
 Input – X = 0.5, Y=0.1
 Input – X = 0.3, Y=0.2
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Complete Geometry
 We can complete the geometry the moving the two vertex in bottom right upward
 Select the vertex to move up
 Use Grid 2D Structured  Edit  Edit Operation
 Input X = 0, Y=0.04, Z=0
 Select other vertex and repeat the same
Grid generated
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BCs and Clustering
 Clustering is increase of density in a location of high gradients
 Assumed by experience like near wall gradients are high
 Use Grid2D Structured Clustering  All Blocks
 Input: One side, 17 points, 0.4%
 Boundary conditions
 Select leftmost edge and assign inflow
 Boundary Condition  Define as Inflow
 Similarly define rightmost edge as outflow
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Simulation
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Simulation
 Fluid Model
 Compressible flow; 2nd order accurate in space
 Flow Conditions
 Freestream Mach – 3.0, pressure and temperature
 Execution Setup
 Time marching – LOCAL – Every cell marches with own speed; CFL number
 Desired residue fall for convergence; Number of iterations for convergence and display after
every iteration
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Result
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Analysis
 We measure the ramp angle – 11.3 degree
 Shock angle obtained ~ 28 degree vs. Theoretical angle – 28.5 degree
 Good matching between theoretical and experiment
Ref: Jet propulsion laboratory
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www.zeusnumerix.com
+91 72760 31511
Abhishek Jain
abhishek@zeusnumerix.com
Thank You !

CFD Lecture (1/8): ZNTutor CFD- An Introduction

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CFD Lecture (1/8): ZNTutor CFD- An Introduction