IRJET- Effect of Applied Pressure Gradient on MHD Flow between Parallel Plates under the Influence of Inclined Magnetic Field by Differential Transform Method

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 10 | Oct 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1600
Effect of Applied Pressure Gradient on MHD flow between Parallel
Plates under the Influence of Inclined Magnetic Field by Differential
Transform Method
Aruna Sharma
Associate Professor, Department of Applied Mathematics, Shah and Anchor Kutchhi Engineering College, Mumbai,
Maharashtra, India
---------------------------------------------------------------------***----------------------------------------------------------------------
Abstract - This paper studies the magnetohydrodynamic flow of a viscous incompressible flow between two parallel infinite
plates under the influence of inclined magnetic field and applied pressure gradient. The upper plate is moving with constant
velocity and the lower plate is held stationary and a pressure gradient is applied to the system which is under the influence of
inclined magnetic field. The resulting governing partial differential equations are nondimensionalised and solvednumericallyby
using the Differential Transform Method. The effect of negative and positive applied pressure gradient, Hartmann number, the
angle of inclination of the magnetic field and the Reynolds Number on the flow field have been represented graphically. It is
observed that an increase in the Hartmann number and the angle of inclination of magneticfielddecreasesthevelocityprofileand
increasing the pressure gradient and Reynolds number effects the velocity profile.
Key Words: Magnetohydrodynamic, Reynolds number, Hartmann number, Pressure gradient, Differential
Transform Method.
1. INTRODUCTION
Magnetohydrodynamic flow between two parallel plates under the influence of inclined magnetic field has many
applications in different fields of Engineering and Technology. The interaction between the conducting fluid andthemagnetic
field modifies the fluid flow and effects the velocity profile depending on the orientation of the magnetic field. When a fluid
moves through a magnetic field an electric field, and consequentlya currentmaybeinduced.Thiscurrentinturninteractswith
the magnetic field to produce a force which effects the velocity of the fluid. In recent years MHD fluid flows has gained interest
due to its widespread application in geothermal, oil reservoir engineering, separation of matter from fluids, MHD power
generator, aerodynamics and nuclear engineering. The influence of magnetic field on a viscous incompressible fluid flow of
electrically conducting fluid is of use in extrusion of plastics, manufacture of rayon, nylon.
Hannas Alfvan [ 20] a Swedish electrical engineer initiated the study of MHD. Shercliff [19] considered the steady motion of
an electrically conducting fluid in pipes under transverse magnetic fields. Drake (1965) considered the flow in channel due to
periodic pressure gradient and solved by the method of separation of variables. Singh [10 ] studied steady MHD flow between
two parallel plates. Manyogne, W A Kiema, Iyaya C W [7] studied the MHD Poiseuille flow between two infinite porous plates
under the influence of magnetic field. Singh [14] investigated the hydromagnetic steady flow of viscous incompressible fluid
between two parallel infinite plates under the influence of inclinedmagneticfield.SinghandOkwoyo[17]carriedouta studyof
couette flow between two infinite parallel plates in the presence of transverse magnetic field. Agnes Mburu, Jackson Kwanza
and Thomas Onyango [21] studied Magnetohydrodynamic fluid flow between two infinite parallel plates subjected to an
inclined magnetic field under Pressure gradient. Despite the investigations done on MHD flow pastparallel platessubjectedto
inclined magnetic field, the effect of negative and positive pressure gradient has received little attention. Here the main
objective of the present investigation is to find the effect of applied pressure gradient and Reynolds number on MHD flow
between two parallel infinite plates under the influence of magnetic field using Differential Transform Method(DTM)
2. MATHEMATICAL FORMULATION
We consider steady viscous flow along the X axis of an electrically conducting fluid between two horizontal parallel infinite
plates located at y=-h and y=h and extending from from x=- ∞ to x=∞ and from z=-∞ to z=∞. The lower plate is stationary and
upper plate is moving with constant velocity U.

Fig 1. Geometrical Configuration of the flow.
3. GOVERNING EQUATIONS
A magnetic field of field strength represented by vector B is applied at right angletothe flowofanelectricallyconductingfluid
moving with velocity V. Assuming that steady state conditions have been attained the interaction of the two fieldsgivesriseto
an electric field E at right angles to both V and B i.e E=V×B. Assuming the conducting fluid is isotropic, we denote its electrical
conductivity by σ. The current density in conducting fluid J= σ E by Ohm’s law. Simultaneously with induced currentoccursan
induced electromotive force called the Lorentz force F= J×B. The equations that describe MHD flow are a combination of a
continuity equation, Navier Stoke’s equations of fluid dynamics and Maxwell’s equation of electromagnetism.
The equation of continuity for the incompressible fluid flow is given by
(1)
where u,v,w are the components of velocity of fluid in the x,y,z directions.
Momentum equations are given as follows:
x-momentum equation is
(2)
y-momentum equation is
(3)
z-momentum equation is
(4)
where are the components of F = J ×B in x, y and z directions respectively.
We are considering a two dimensional flow, therefore equation (1) reduces to
(5)
The plates are of infinite length, so we assume the flow is along x-axis only i.e velocity profile along the y and z axis v=w=0
and u depends on y only.

Therefore, (6)
Since we have assumed steady flow, i.e flow variables are independent of time,
(7)
Therefore, equations (2), (3) and (4) can be written as
(8)
(9)
Where, , and are the components of the Lorentz force F, as the body force is neglected and replaced by Lorentz force.
Since there is no flow in the y-direction, using (5) and (6), we can rewrite the equations (8), (9) as
(10)
(11)
There is no component of body force in y direction, and and as v=w=0, the equation of motion
becomes
(12)
(13)
Since we are considering the flow in x-direction then the flow will be affected by the magnetic flux which is perpendicular to
the flow. Since we want to study the effect of different angles of inclination of the magnetic field thenthevelocityandmagnetic
flux profiles will be
V=V (u,0,0)
B=B(0,B
Where is the angle between V and B
Equation (13) implies p does not depend on y.
Since, J=σE and E= , where V is the fluid velocity along x-axis, the direction of fluid flow
Now, E= = = uBsin θ (14)
Now, J=σE = σ uBsin θ
= = - σuB2

Therefore, - σ B2 u (15)
Using (15), the equation of motion reduces to
(16)
4. NON -DIMENSIONALIZATION
To simplify (16) we non dimensionalize to reduce the parameters in the equation by using the following non dimensional
quantities.
, , , , Re= where ν =
Now , =
=
(17)
Now, =
(18)
=
= (19)
Next, =
=
=
=
(20)
Similarly , (21)
Substituting in equation (13) and (16) we get,
(22)
(23)

(24)
Dividing throughout by
(25)
Now writing Re= and M2 = i.e M= Bh
Dropping the from equation (16) and (25) and simplifying we get
(26)
(27)
Where Re is called as the Reynold’s Number and M is the Hartmann Number.
Differentiating equation (27) w.r.t x , We get
(28)
Since P does not depend on y we express equation (28) as a total derivative
=0 (29)
From (29), we get
= (a constant) (30)
u depends only on y equation (27) reduces to
(31)
Equation (31) can be solved using boundary conditions
u=0, when y=-h
u=U, when y=h.
The non dimensional form of these boundary conditions are u=0, when y=-1
u=1, when y=1
The equation (31)) is solved numerically by Differential Transform Method (DTM)
5. METHODOLOGY
The Differential Transform Method (DTM) is a numerical method for solving differential equations which was proposed by
Zhou[1986] .The DTM gives exact values of the nth order derivative of the analytic function at a point in terms of known and
unknown boundary conditions in a fast manner, The DTM Technique uses the polynomials to approximatetheexactsolution.
The differential transform of the kth derivative of the function u(x) is defined as follows

and the differential inverse transform of U(k) is defined as
In real application, the function is expressed as a finite series.
We apply DTM to equation (31) and express it in the form
where is assumed to be negligible.
The following theorems can be deduced
Theorem 1. If then
Theorem 2. If then
, where ‘a’ is a constant.
Theorem 3. If , then
=0
6. SOLUTION
Applying DTM to equation (31) and using theorem 1 to 5, we get
(32)
Where and
(33)
and is assumed to be negligibly small.
From ( 32) we get the recurrence relation,
(34)

For k=0,1……… we find U(2), U(3),U(4) …….and so on in terms of U(0) and U(1).
Now from (33), we express u(y) as a series, taking n=11
u(y)=U(0)+U(1)y+U(2)y2+U(3)y3+…….+U(11)y11
(35)
Substituting the boundary conditions u(-1)=0 and u(1) =1 in above we get
U(0)-U(1)+U(2)-U(3) +…………..-U(11)=0
U(0)+U(1)+U(2)+U(3) +…………..+U(11)=1
Adding and subtracting the above two equations we get,
U(0)+U(2)+U(4) +…………..+U(10)=.5 (36)
U(1)+U(3)+U(5) +…………..+U(11)=.5 (37)
By assigning values to M, P ,Re and Theta, we obtain U(2),U(3) ,U(4),U(5)…….U(11) in terms of U(1) and U(0) using equation
(34)
These are further substituted in equation (36) and (37) to get U(0) and U(1) .
Using U(0) and U(1) thus calculated we resubstitute to obtain U(2),U(3) ,U(4),U(5)…….U(11)
These known values are substituted in the series u(y) in equation (33) and for different values of y the velocity profile is
obtained.
7. TABLES AND GRAPHS
From the above methodology, using MATLAB the velocity profile has been calculated for different values of angle of
inclination, Hartmann number, Pressure gradient P and Reynolds Number and the tables and graphs have been shown.
Table 1: Different Values of Theta
y theta=pi/6 theta=pi/4 theta=pi/3 theta=pi/2
-1 0 0 0 0
-0.8 0.0822 0.0554 0.0402 0.0308
-0.6 0.1596 0.1073 0.0773 0.0585
-0.4 0.2354 0.1597 0.1156 0.0875
-0.2 0.3127 0.217 0.1598 0.1227
0 0.3944 0.2836 0.2153 0.1696
0.2 0.484 0.3651 0.2889 0.2359
0.4 0.5849 0.4679 0.3894 0.3324
0.6 0.7013 0.6003 0.529 0.4747
0.8 0.8379 0.7731 0.7246 0.6858
1 1 1 1 1

Fig 2. Velocity profile for Different Values of Theta, M=2, P=1, Re=.2
In Table 1. The velocity of fluid has been calculated for different angles of inclination of the magnetic field by using DTM
method and it is observed that as angle of inclination of the magnetic fieldincreases,thevelocityprofiledecreases whichcanbe
observed in the graph shown in Fig 2.
Table 2: Different values of M
P=1, Theta=60, Re=.2
y M=.5 M=1 M=1.5 M=2
-1 0.0000 0.0000 0.0000 0.0000
-0.8 0.1223 0.0920 0.0621 0.0402
-0.6 0.2376 0.1788 0.1204 0.0773
-0.4 0.3466 0.2630 0.1789 0.1156
-0.2 0.4503 0.3470 0.2414 0.1598
0 0.5493 0.4334 0.3122 0.2153
0.2 0.6444 0.5249 0.3962 0.2889
0.4 0.7363 0.6241 0.4991 0.3894
0.6 0.8258 0.7341 0.6278 0.5290
0.8 0.9135 0.8582 0.7911 0.7246
1 1.0000 1.0000 1.0000 1.0000
Fig 3.Velocity profile for Different Values of M

In Table 2, for different values of Hartmann number the velocity profile has been calculated and shown graphically. Fig 3
shows that as Hartmann number increases there is a decrease in the velocity. This is because Hartmann number is ratio of
magnetic forces to viscous forces so larger the Hartmann number, stronger the magneticforceswhichreducesthe velocitydue
to action of Lorentz forces.
Table 3. Different values of Re (Reynolds number)
P=1, M=2, Theta= 60
y Re=.2 Re=.4 Re=.6 Re=.8
-1 0 0 0 0
-0.8 0.0402 0.0583 0.0764 0.0945
-0.6 0.0773 0.1075 0.1378 0.1681
-0.4 0.1156 0.1537 0.1917 0.2298
-0.2 0.1598 0.2022 0.2446 0.287
0 0.2153 0.2591 0.3029 0.3467
0.2 0.2889 0.3313 0.3737 0.4161
0.4 0.3894 0.4275 0.4655 0.5036
0.6 0.529 0.5593 0.5896 0.6199
0.8 0.7246 0.7427 0.7608 0.7789
1 1 1 1 1
Fig 4. Velocity profile for Different Values of Re, P=1
In Table 3, for different values of Re but P positive the values of velocity profile have calculated by DTM method and shown
graphically. Fig 4. Shows the effect of increase in Reynolds number when P is positive.
When P is positive, the pressure gradient is negative. This negative pressure gradient indicates the pressure is decreasing in
the x direction along with decreasing viscous forces because of increased Reynolds number causes an increase in velocity
profile.
Table 4. Different values of Re (Reynolds number)
P= , M=2, Theta= 60
Y Re=.2 Re=.4 Re=.6 Re=.8
-1 0 0 0 0
-0.8 -0.014 -0.0502 -0.0864 -0.1226
-0.6 -0.0136 -0.0742 -0.1348 -0.1953

Fig 5. Velocity profile for Different Values of Re, P=
In Table 4, for different values of Re but P negative the values of velocity profile have been calculated by DTM method and
shown graphically.Fig.5 shows the effect of increase in Reynolds number, when P is negative. When P is negative,thepressure
gradient is positive. This positive pressure gradient called as adverse pressure gradient means theflowismovingintoa region
of increasing pressure which will cause a decrease in velocity as the fluid motion created by the plate is not strong enough to
overcome this pressure gradient even as Reynolds number increases
Table 5: Different Values of P
-0.4 0.0013 -0.0748 -0.151 -0.2271
-0.2 0.0326 -0.0522 -0.137 -0.2218
0 0.084 -0.0036 -0.0912 -0.1788
0.2 0.1617 0.0769 -0.008 -0.0928
0.4 0.2751 0.199 0.1228 0.0467
0.6 0.4381 0.3775 0.317 0.2564
0.8 0.6704 0.6342 0.598 0.5618
1 1 1 1 1
y P=-3 P= -2 P=-1 P=0 P=1 P=2
-1 0 0.0000 0 0 0 0
-0.8 -0.0321 -0.014 0.0041 0.0221 0.0402 0.0583
-0.6 -0.0439 -0.0136 0.0167 0.047 0.0773 0.1075
-0.4 -0.0367 0.0013 0.0394 0.0775 0.1156 0.1537
-0.2 -0.0098 0.0326 0.075 0.1174 0.1598 0.2022
0 0.0402 0.084 0.1278 0.1716 0.2153 0.2591
0.2 0.1193 0.1617 0.2041 0.2465 0.2889 0.3313
0.4 0.2371 0.2751 0.3132 0.3513 0.3894 0.4275
0.6 0.4078 0.4381 0.4684 0.4987 0.529 0.5593
0.8 0.6523 0.6704 0.6884 0.7065 0.7246 0.7427
1 1 1 1 1 1 1

Fig 6. Velocity profile for Different Values of P for M=2, theta=60, Re=.2
In Table 5. The velocity profile has been calculated for different values of P using DTM methodandshowngraphically.Fig.6
shows the effect of pressure gradient on the fluid flow. It is observed that when P is positive (P=1, 2), the pressure gradient
.That is we have a negative pressure gradient which favors the flow and overcomes the shear stress and the
velocity increases across the plate.
When P is negative (P=-3,-2,-1),the pressure gradient .That is we have a positive pressure gradient or
adverse pressure gradient which fluids find difficult to negogiate therefore the velocity becomes negative in the lower half
region and then increases slowly across the plate. .As P increases from negative to positive it is observed that the velocity of
fluid increases as the pressure gradient is increasing from positive to negative.
8. VALIDATIONS OF RESULTS:
The results obtained by using DTM were compared with Singh (2014) who usedananalyticmethodandwerefoundtointotal
agreement. However he had not considered the effect of negative andpositivepressuregradientand Reynoldsnumberonfluid
flow.
9. RESULTS AND DISCUSSION
The problem of the effect of inclined magnetic field, pressure gradient on MHD flow between two infinite parallel plates with
upper plate moving with constant velocity and lower plate stationary along with applied pressure gradient has been
investigated. From the analysis the following results were observed
9.1 As the angle of inclination of magnetic field increases it is found that there is a decrease in the velocity profile.
9.2 As the strength of the magnetic field increases, there is a decrease in the velocity profile.
9.3. Negative and positive pressure gradient increase or decrease the velocity
9.4 Increase in Reynolds number effects the velocity of flow.
10. CONCLUSION
The study concerns the effect of inclination of magnetic field, Pressure gradient, Reynolds number on MHD flow between
parallel plates. The results obtained using DTM are in agreementwiththeanalyticmethodandshowthatforanincreasedangle
of inclination of magnetic field the velocity decreases. An increase in the magnetic field strength M also results in decrease in
the velocity. Further, the effect of pressure gradient on the fluid flow has been observed, where negativeandpositivepressure
gradient increases and decreases the flow rate respectively. Also it is observed that increase in Reynolds number results in
increase or decrease of velocity depending on whether a negative or positivepressure gradientisapplied,whichcanbeused in

controlling the flow in some engineering problems. Pressuregradientisoneofthefactorsthatinfluencea fluidflow immensely.
Differential Transform method is found to be fast, accurate and converges very fast to the exact solution.
REFERENCES
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4) D.W. Kiema, WA Manyonge, J K Bitok, “On the steady MHD Poiseuille flow betweentwo infiniteparallel porousplates”,
International Journal of Scientific research and Innovative Technology, Vol 2, No.2, February 2015.
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BIOGRAPHIES
Prof. Aruna Sharma is an Associate Professor in Department of Mathematics at Shah and Kutchhi Engineering
College, Mumbai. She has completed her M Sc. from Mumbai University and is pursuing her PhD at Pacific
University, Udaipur. She has a total Teaching experience of over thirty years in Applied Mathematics. Her area of
research is Fluid Dynamics.

IRJET- Effect of Applied Pressure Gradient on MHD Flow between Parallel Plates under the Influence of Inclined Magnetic Field by Differential Transform Method

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