Numerical solution of free convection MHD micropolar fluid flow between two parallel porous vertical...
Transcript of Numerical solution of free convection MHD micropolar fluid flow between two parallel porous vertical...
Numerical solution of free convection MHD micropolarfluid flow between two parallel porous vertical plates
R. Bhargava a, L. Kumar a, H.S. Takhar b,*
a Department of Mathematics, Indian Institute of Technology, Roorkee 247667, Indiab Department of Engineering, Manchester Metropolitan University, Manchester M1 5GD, UK
Received 7 August 2002
(Communicated by E.S. S�UHUB_II)
Abstract
The fully developed electrically conducting micropolar fluid flow between two vertical porous parallel
plates is studied in the presence of temperature dependent heat sources including the effect of frictional
heating and in the presence of a magnetic field. Profiles for velocity, microrotation and temperature are
presented for a wide range of Hartmann numbers and the micropolar parameter. The skin friction, couple
stress and Nusselt numbers at the plates are shown in the tables.
� 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
With the enormous expansion of engineering industries based on non-Newtonian fluids, such aspseudoplastic, dilatant, rheopetic, suspension flows, a lot of research attention has been given inthis direction. The theory of microfluids as developed by Eringen [1], which includes the effect oflocal rotary inertia, the couple stresses and inertial spin satisfactorily provides a model for thenon-Newtonian behavior observed in the polymers, paints, lubricants, suspended fluids and bloodetc.Eringen [2] also developed the theory of micropolar fluids for the case where only microrota-
tional effects and microrotational inertia exist. He [3] extended the theory of thermomicropolarfluids and derived the constitutive laws for fluids with microstructure. Simple problems on the
*Corresponding author. Tel.: +44-161-247-3668.
E-mail address: [email protected] (H.S. Takhar).
0020-7225/03/$ - see front matter � 2002 Elsevier Science Ltd. All rights reserved.
PII: S0020-7225(02)00157-X
International Journal of Engineering Science 41 (2003) 123–136www.elsevier.com/locate/ijengsci
flow of such fluids were studied by a number of researchers and a review of this work was given byAriman et al. [4].Balaram and Sastry studied the fully developed free convection flow in a micropolar flow [5].
Later Jena and Mathur [6] examined the free convective heat transfer to a micropolar fluid along anon-isothermal vertical plate. Agarwal and Dhanapal [7] have analysed the effect of temperaturedependent heat sources on the fully developed free convection micropolar fluid flow when aconstant suction (or injection) is applied on the plates and the fluid.The extension of above type of flows to include magnetohydrodynamic effects has become
important due to several engineering applications such as in MHD generators, designing coolingsystem for nuclear reactors, flow meters, etc. where the microconcentration provides an impor-tant parameter for deciding the rate of heat flow. By simulating it, one can obtain the desiredtemperature in such equipments. Several investigators have made theoretical and experimentalstudies of micropolar flow in the presence of a transverse magnetic field during the last threedecades.Kasivishwanathan and Gandhi [8] have studied a class of exact solutions for the MHD flow of
a micropolar fluid confined between two infinite, insulated, parallel, non-coaxially rotating disks.Mohammeadein and Gorla [9] investigated the transverse magnetic field on mixed convection ina micropolar fluid flowing on a horizontal plate with vectored mass transfer. Later Gorla andTakhar [10] examined the simultaneous occurrence of buoyancy and magnetic forces in the flowof an electrically conducting micropolar fluid along a hot vertical plate in the presence of astrong cross magnetic field. The results indicate that the micropolar fluids reduce drag andsurface heat transfer rate. The general theory of magneto-micropolar fluids can be found inEringen [11].In the present paper, we have analysed the effect of temperature dependent heat sources on the
fully developed free convection electrically conducting micropolar fluid between two parallelporous vertical plates in a strong cross magnetic field. The governing differential equations havebeen solved by using the Quasi-linearization method. The velocity, microrotation and temperaturefunctions are shown graphically and the effects of magnetic field and micropolar parameter arestudied.
2. Mathematical formulation
Consider the fully developed steady, laminar free convection flow of an incompressible mi-cropolar fluid flowing between two infinite parallel porous flat plates distance h apart and orientedin the direction of the body force. The plates are maintained at constant temperature T1 and T2, inthe presence of strong magnetic field H0 normal to the plate. The x axis is taken along one of theplates and y axis normal to it. Since the boundaries in the x direction are of infinite dimensionstherefore without any loss of generality we assume that the physical quantities, for example ve-locity, microrotation and temperature depends on y only. The velocity field is taken to be ðu; t; 0Þand microrotation as ð0; 0;NÞ.It is assumed that the fluid possesses constant properties except the density variation due to
temperature difference is used only to express the body force term as the buoyancy term. Thus thegoverning equations of such type of flow can be written as:
124 R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136
otoy
¼ 0; giving t ¼ t0 ðconstantÞ ð1Þ
qt0ouoy
¼ ðl þ KÞ o2uoy2
þ KoNoy
þ qf � opox
þ rH 20 u ð2Þ
qjt0oNoy
¼ co2Noy2
� K 2N�
þ ouoy
�ð3Þ
qcpt0oToy
¼ Kfo2Toy2
þ ðl þ KÞ ouoy
� �2
þ coNoy
� �2
þ 2K N 2
�þ N
ouoy
�þ c0t0ðT � T0Þ ð4Þ
where c0 is the constant of proportionality, c0t0ðT � T0Þ the amount of heat generated per unitvolume in unit time is assumed to be a linear function of temperature, p the pressure, q thedensity, f the body force, cp the specific heat, l the coefficient of viscosity, K the gyroviscosity,c the material constant, j the microinertia and Kf the coefficient of thermal conductivity andT0 is the temperature in hydrostatic state.The boundary conditions are given by
at y ¼ 0 : u ¼ 0; t ¼ t0; T ¼ T1; N ¼ 0
at y ¼ h : u ¼ 0; t ¼ t0; T ¼ T2; N ¼ 0ð5Þ
where t0 < 0 implies injection at y ¼ h and suction at y ¼ 0 while t0 > 0 represents injection aty ¼ 0 and suction at y ¼ h.The body force term is expressed as a buoyancy term,
qf � opox
¼ qbðT � T0Þfx ð6Þ
where fx ¼ �f , pD ¼ ðp � p0Þ is the pressure difference, p0 being the hydrostatic pressure and b isthe coefficient of volumetric expansion.As the plates are infinitely long, the pressure p can be taken equal to the hydrostatic pressure p0,
i.e. pD ¼ 0:Using Eq. (6), Eqs. (2)–(4) can be written as
d2udy2
� qt0ðl þ KÞ
dudy
þ Kðl þ KÞ
dNdy
þ qbfxðT � T0Þðl þ KÞ � rH 2
0 uðl þ KÞ ¼ 0 ð7Þ
d2Ndy2
� qjt0c
dNdy
� Kc
2N�
þ dudy
�¼ 0 ð8Þ
R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136 125
d2ðT � T0Þdy2
� qcpt0Kf
dðT � T0Þdy
þ ðl þ KÞKf
dudy
� �2
þ cKf
dNdy
� �2
þ 2KKf
N 2
�þ N
dudy
�
þ c0t0ðT � T0ÞKf
¼ 0 ð9Þ
Introducing the following dimensionless variables
y ¼ gh; u ¼ KfUqfxbh2
; ðT � T0Þ ¼Kfl:T �
q2f 2x b2h4
; N ¼ KfN �
qfxbh3ð10Þ
and substituting the above transformations into the Eqs. (7)–(9), we obtain
d2Udg2
� Reð1þ RÞ
dUdg
þ T �
ð1þ RÞ þR
ð1þ RÞdN �
dg� H 2
a CU ¼ 0 ð11Þ
d2N �
dg2� Reb
AdN �
dg� RA
2N ��
þ dUdg
�¼ 0 ð12Þ
d2T �
dg2� RePr
dT �
dgþ ð1þ RÞ dU
dg
� �2
þ AdN �
dg
� �2
þ 2R N �2�
þ N � dUdg
�þ c1RePrT
� ¼ 0
ð13Þ
where R ¼ ðK=lÞ is the micropolar parameter, Re ¼ ðqt0h=lÞ the cross flow Reynolds number,A ¼ ðc=lh2Þ, B ¼ ðj=h2Þ and C ¼ ðh2=ð1þ RÞÞ the micropolar material constants, Pr ¼ ðlcp=Kf Þthe Prandtl number, c1 ¼ ðc0h=qcpÞ the dimensionless vertical distance, Ha ¼ ððrH 2
0 =lÞÞ1=2
is thelocal Hartmann number.The corresponding boundary conditions given in Eq. (5) then reduces to
at g ¼ 0; U ¼ 0; N � ¼ 0; T � ¼ Q
at g ¼ 1; U ¼ 0; N � ¼ 0; T � ¼ eQð14Þ
where Q ¼ ðPrGrbfxh=cpÞ is a dimensionless group, Gr ¼ ðq2bfxh3ðT � T0Þ=l2Þ is the Grasshofnumber and e ¼ ððT2 � T0Þ=ðT1 � T0ÞÞ is the non-dimensional heating parameter.The dimensionless shear stress, couple stress and the Nusselt number at the plates are given by
s� ¼ ð1�
þ RÞ dUdg
�at g¼0;1
M� ¼ dN �
dg
� �at g¼0;1
ð15Þ
126 R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136
Nu ¼ � 1
QdT �
dg
� �at g¼0;1
; for e ¼ 1
¼ 1
ðe � 1ÞQdT �
dg
� �at g¼0;1
; for e 6¼ 1
ð16Þ
3. Method of solution: Quasi-linearization method
The set of Eqs. (11)–(13) are highly non-linear therefore this system of equations cannot besolved analytically. The Quasi-linearization method has been used to solve it, which is illustratedas follows:The Quasi-linearization method, which is also known as the generalized Newton–Raphson
method, was given by Bellman and Kalaba, details of which can be seen in [12]. However anexplanation of the method is given in Appendix A. This method is used due to following ad-vantages.
(1) The method is quadratically convergent, starting from the initial guess value.(2) The solution is valid for a large range of parameters. Even when the required number of initial
conditions are not given, this method converges at a fast speed.
In order to implement the quasi-linearization technique, the system of Eqs. (11)–(13) is con-verted to a system of first order differential equations as follows:
U ;U 0;N �;N �0 ; T �; T �0� �
¼ ðx1; x2; x3; x4; x5; x6Þ ð17Þ
The Eqs. (11)–(13) are replaced by the following equivalent system of six first order ordinarydifferential equations,
dx1dg
¼ x2
dx2dg
¼ Reð1þ RÞ x2 �
Rð1þ RÞ x4 �
x5ð1þ RÞ þ H 2
a Cx1
dx3dg
¼ x4
dx4dg
¼ ReBA
x4 þRAð2x3 þ x2Þ
dx5dg
¼ x6
dx6dg
¼ RePr x6 � ð1þ RÞx22 � Ax24 � 2R x23�
þ x3x2�� c1RePr x5
ð18Þ
R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136 127
Applying the quasi-linearization algorithm as given in Appendix A on the set of Eq. (18) we get:
dxðkþ1Þ1
dg¼ xðkþ1Þ2
dxðkþ1Þ2
dg¼ Re
ð1þ RÞ xðkþ1Þ2 � R
ð1þ RÞ xðkþ1Þ4 � xðkþ1Þ5
ð1þ RÞ þ H 2aCx
ðkþ1Þ1
dxðkþ1Þ3
dg¼ xðkþ1Þ4
dxðkþ1Þ4
dg¼ ReB
Axðkþ1Þ4 þ R
A2xðkþ1Þ3
�þ xðkþ1Þ2
�
dxðkþ1Þ5
dg¼ xðkþ1Þ6
dxðkþ1Þ6
dg¼ RePr xðkþ1Þ6 � ðRþ 1Þ 2xðkþ1Þ2 xk2
h� xk2x
k2
i� A 2xðkþ1Þ4 xk4
h� xk4x
k4
i
� 2R 2xðkþ1Þ3 xk3h
� xk3xk3 þ xk2x
ðkþ1Þ3 þ xk3x
ðkþ1Þ2 � xk2x
k3
i� c1RePr x
ðkþ1Þ5
ð19Þ
Boundary conditions given by (14) now reduces to:
xkþ11 ð0Þ ¼ 0; xkþ11 ð1Þ ¼ 0
xkþ13 ð0Þ ¼ 0; xkþ13 ð1Þ ¼ 0
xkþ15 ð0Þ ¼ Q; xkþ15 ð1Þ ¼ eQ
ð20Þ
The system given by Eq. (19) is linear xðkþ1Þi and its general solution can be obtained by using theprinciple of superposition.The initial values for xðkþ1Þi are chosen as follows:
(i) For the particular solution
P ðkþ1Þi ð0Þ ¼ ð0; 0; 0; 0;Q; 0Þ ð21Þ
(ii) For the homogeneous solution
Hi2ð0Þ ¼ ð0; 1; 0; 0; 0; 0ÞHi4ð0Þ ¼ ð0; 0; 0; 1; 0; 0ÞHi6ð0Þ ¼ ð0; 0; 0; 0; 0; 1Þ
ð22Þ
The general solution of system of Eq. (19) is given by
xðkþ1Þi ðgÞ ¼ P ðkþ1Þi ðgÞ þ C2Hi2ðgÞ þ C4Hi4ðgÞ þ C6Hi6ðgÞ ð23Þ
128 R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136
where C2;C4 and C6 are the unknown constants and are determined by considering the boundaryconditions at g ¼ 1:The following expressions obtained for C2;C4 and C6 arise, viz
C2 ¼D1
D; C4 ¼
D2
D; C6 ¼
D3
D
where
D ¼ H12ð1Þ H34ð1ÞH56ð1Þ½ � H36ð1ÞH54ð1Þ � H14ð1Þ H32ð1ÞH56ð1Þ½ � H36ð1ÞH52ð1Þþ H16ð1Þ H32ð1ÞH54ð1Þ½ � H52ð1ÞH34ð1Þ
D1 ¼ �P ðkþ1Þ1 ð1Þ H34ð1ÞH56ð1Þ½ � H36ð1ÞH54ð1Þ � H14ð1Þ
h� P ðkþ1Þ
3 ð1ÞH56ð1Þ
� eQ�
� P ðkþ1Þ5 ð1Þ
�H36ð1Þ
iþ H16ð1Þ
h� P ðkþ1Þ
3 ð1ÞH54ð1Þ � eQ�
� P ðkþ1Þ5 ð1Þ
�H34ð1Þ
i
D2 ¼ H12ð1Þh� P ðkþ1Þ
3 ð1ÞH56ð1Þ � eQ�
� P ðkþ1Þ5 ð1Þ
�H36ð1Þ
iþ P ðkþ1Þ
1 ð1Þ H32ð1ÞH56ð1Þ½
� H36ð1ÞH52ð1Þ þ H16ð1Þ eQ�h
� P ðkþ1Þ5 ð1Þ
�H32ð1Þ þ P ðkþ1Þ
3 ð1ÞH52ð1Þi
D3 ¼ H12ð1Þ eQ�h
� P ðkþ1Þ5 ð1Þ
�H34ð1Þ þ P ðkþ1Þ
3 ð1ÞH54ð1Þi� H14ð1Þ eQ
�h� P ðkþ1Þ
5 ð1Þ�H32ð1Þ
þ P ðkþ1Þ3 ð1ÞH52ð1Þ
i� P ðkþ1Þ
1 ð1Þ H32ð1ÞH54ð1Þ½ � H34ð1ÞH52ð1Þ
The set of differential equations given in (19), have been solved by employing the fourth orderRunge Kutta method for the boundary condition given in (20) and solution is obtained by in-voking the principle of superposition. The whole range is divided into 40 equal parts with equalsub intervals of width 0.025; and accuracy has been taken as 0.0005.
4. Results and discussion
On solving the system of equations, given by (11)–(13), with boundary conditions (14), thevelocity, microrotation and temperature distribution are obtained. The Prandtl number Pr, ma-terial constant c1 and the micropolar material constants A, B and C are taken to be constant, at0.733, 1.0, 1.0, 0.001 and 1.0 respectively whereas the effect of other important parameters, namelymicropolar parameter R, the cross flow Reynolds number Re and local Hartmann number Ha hasbeen studied for these functions and the corresponding profiles are shown in the Figs. 1–6.Fig. 1 depicts the variation of velocity function U with Hartmann number Ha for a prescribed
value of micropolar parameter R ¼ 3: Profiles are shown both for positive Re ð¼ 2Þ (i.e. for in-jection at g ¼ 0 and suction at g ¼ 1) and negative Re ð¼ �2Þ (i.e. for suction at g ¼ 0 and in-jection at g ¼ 1). The velocity profiles are parabolic in nature and attain their maximum near themiddle. However for negative cross flow Reynolds number, the maximum is shifted towards
R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136 129
g ¼ 0. It is observed that the velocities are higher for injection as compared to suction at g ¼ 0.The velocity continuously decreases with an increase in Hartmann number. The same pattern isobserved for both values of cross flow Reynolds number Re. This indicates that the fluid velocitycan be reduced by an increase in the magnetic field, a similar phenomenon is observed in [10].The variation in the velocity with reference to the variation in micropolar parameter R for
constant magnetic field is presented in Fig. 2. The results are given for both positive and negativecross flow Reynolds number Re. It is observed that the velocity values for injection are more thanthat for suction at g ¼ 0. As the micropolar parameter R increases, the velocity continuouslydecreases, the maximum being shifted towards g ¼ 1. But for suction the maximum is closer tog ¼ 0. This is however different as compared to viscous flow which correspond to R ¼ 0. It isreally interesting to observe this behavior of micropolar flow. The boundary layer thickness, asexpected, continuously decreases with increase in microconcentration.
Fig. 1. Velocity distributions for various H 2a .
Fig. 2. Velocity distributions for various R.
130 R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136
The effect of the Hartmann number Ha on microrotation when the micropolar parameter R
kept fixed at 3, is shown in Fig. 3. The values of microrotation are negative in the first halfwhereas in the second half, these are positive, thus showing a reverse rotation near the twoboundaries. Moreover for injection these are higher numerically as compared to suction at g ¼ 0.An increase in the magnetic field leads a to decrease in microrotation. The intensity of themagnetic field thus can be used for decreasing the angular rotation especially in suspension flows,commonly arising in lubrication problems.Fig. 4 illustrates that the microrotation continuously increases with an increase in the micro-
polar parameter R for a fixed value of the magnetic field. As expected the increase in micro-concentration enhances the angular rotation. It is clear from this figure that the microrotation is
Fig. 3. Microrotation for various H 2a .
Fig. 4. Microrotation for various R.
R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136 131
negative in the first half while it is positive in the second half. The values for injection are againhigher numerically as compared to suction at g ¼ 0.The temperature variation is shown in Figs. 5 and 6 both for the injection and suction cases. It
is observed that the temperature distribution depends upon e, however for Re > 0; it increases anda attains maximum and then decreases. While for Re < 0; it continuously decreases. This happensfor e > 1 as well as for e < 1:The skin friction and Nusselt number has been given for Re ¼ 2 and �2 in the Tables 1 and 2
respectively which show their variation with respect to the micropolar parameter R and Hartmannnumber Ha. From the numerical results obtained as given in Table 1, it is noticed that the skin
Fig. 5. Temperature distribution for various H 2a .
Fig. 6. Temperature distribution for various R.
132 R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136
friction for injection increases with an increase in the Hartman number Ha while keeping themicropolar parameter R fixed, thus causing more resistance. However it decreases with an in-crease in the micropolar parameter R, for a fixed Ha. But for the suction case, the skin frictiondecreases with an increase in Hartmann number Ha, for a fixed R. A similar pattern is observedfor injection with an increase in the micropolar parameter R with a fixed Hartmann number Ha.From Table 2, it is observed that the rate of cooling increases with an increase in the Hartmann
number Ha and also with the micropolar parameter R. Similar pattern is observed for suction.This implies that the magnetic field as well as microconcentration are the important parameters inreducing heating effects and can be used for controlling the rate of heat transfer, which is desiredin many MHD applications.
5. Conclusions
The velocity decreases with an increase in Hartmann number. Values for positive cross flowReynolds number are higher as compared to those for )ve Reynolds number.The microrotationincreases with an increase in microconcentration while it decreases with an increase in the mag-netic field. The micropolar effects behave as a coolant and are thus effective in reducing the coolingrate and help in producing the desired temperature. The magnetic field can be used effectively forcontrolling the rate of heat transfer as required in MHD applications like MHD generators,nuclear reactors, where it is used to control enormous temperatures.
Table 1
Values of f�f 00ð0Þg for different values of the Hartmann number (Ha) and micropolar parameter (R) with Re þveand )ve
Re ¼ 2 Re ¼ �2H 2
a R ¼ 3 R H 2a ¼ 5 H 2
a R ¼ 3 R H 2a ¼ 5
0 0.146179 0 0.418457 0 0.270853 0 1.744551
1 0.153360 1 0.313665 1 0.268153 1 0.648696
5 0.172302 3 0.172302 5 0.260610 3 0.260610
10 0.184977 5 0.108876 10 0.254872 5 0.152236
e ¼ 1, Q ¼ 1, B ¼ 0:001, Pr ¼ 0:733, A ¼ 1:0, c ¼ 1:0, C ¼ 1:0.
Table 2
Values of f�T 0ð0Þg for different values of the Hartmann number (Ha) and micropolar parameter (R) with Re þveand )ve
Re ¼ 2 Re ¼ �2H 2
a R ¼ 3 R H 2a ¼ 5 H 2
a R ¼ 3 R H 2a ¼ 5
0 )0.623848 0 )0.628725 0 0.777345 0 0.768676
1 )0.621962 1 )0.622106 1 0.778835 1 0.777926
5 )0.617790 3 )0.617790 5 0.782115 3 0.782115
10 )0.615644 5 )0.616200 10 0.783783 5 0.783436
e ¼ 1, Q ¼ 1, B ¼ 0:001, Pr ¼ 0:733, A ¼ 1:0, c ¼ 1:0, C ¼ 1:0.
R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136 133
Appendix A
Let us consider the vector equation
dxidt
¼ gi xj; t� �
; ði; j ¼ 1; 2; . . . . . . . . . ; nÞ ðA:1Þ
where �t�, is the independent variable, defined in the closed domain [a,b], subject to the boundaryconditions:
xpðaÞ ¼ ap ðp ¼ 1; 2; . . . . . . . . . ; nÞxqðbÞ ¼ bq ðq ¼ 1; 2; . . . . . . . . . ; nÞ
ðA:2Þ
here xi, gi are taken as vectors in the nth dimensional space. The ðk þ 1Þth approximation xðkþ1Þi tothe solution of (A.1) is obtained by expanding the functional gi about the kth approximation xki ,and retaining only the linear and constant terms. The kth approximation xki is assumed to be a setof known approximate solutions.The general form of the quasi-linearization algorithm is,
dxðkþ1Þi
dt¼ gi xkj ; t
� �þXn
j¼1
ogioxj
� �k
xðkþ1Þj
�� xkj
�ðA:3Þ
where ðogi=oxjÞk is the Jacobian matrix evaluated at the kth approximation and is defined as:
ogioxj
� �k
¼
og1oxðkÞ1
og1oxðkÞ2
. . .og1oxðkÞn
. . . . . . . . . . . .ognoxðkÞ1
ognoxðkÞ2
. . .ognoxðkÞn
266664
377775 ðA:4Þ
The superscripts in the parenthesis denote the iteration number. The boundary conditions for theðk þ 1Þth approximation xðkþ1Þi are given by,
xðkþ1Þp ðtÞjt¼a ¼ ap ðA:5Þ
xðkþ1Þq ðtÞjt¼b ¼ bq ðA:6Þ
The system of differential Eq. (A.3) is linear in xðkþ1Þi and is non-homogeneous. Its solution can beobtained by invoking the principle of superposition, i.e. by adding the �n� homogeneous solutionsof the corresponding �n� homogeneous equations (obtained by making the non-homogeneous termequal to zero), to the particular solution. A particular solution can be obtained by integrating(A.3) with approximate initial conditions. For simplicity, the initial values may be assumed as,
PiðtÞjt¼a ¼ xiðtÞjt¼a ¼ hi ðA:7Þ
where hi is the ith component of null vector, and Pi is the corresponding particular integral.
134 R. Bhargava et al. / International Journal of Engineering Science 41 (2003) 123–136
Besides the particular solution, there exist �n� linearly independent solutions of the homoge-neous equations,
dxðkþ1Þj
dt¼
Xn
j¼1xðkþ1Þj
ogioxj
� �k
ðA:8Þ
The initial conditions for the jth solution of this equation may be assumed as
H ðkþ1Þij ðtÞjt¼a ¼ xðkþ1Þij ðtÞjt¼a ¼ dij; i; j ¼ 1; 2; . . . . . . . . . ; n ðA:9Þ
where
dij ¼ 1 for i ¼ j¼ 0 for i 6¼ j
Hence the general solution may be written as,
xðkþ1Þi ¼ Pi þXn
j¼1AjHij ðA:10Þ
The coefficients Aj may be obtained by satisfying the conditions at the boundaries (A.5) and (A.6).Hence
Pnj¼1
AjHmjðtiÞ ¼ Bi � PmðtiÞ; i ¼ 1; 2; . . . . . . . . . ; n
m ¼ Mi
ðA:11Þ
The approximation xðkþ1Þi is next feed back into the algorithm to obtain the approximation xðkþ2Þi
and the process is repeated until satisfactory results are obtained.
References
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[2] A.C. Eringen, Theory of micropolar fluids, J. Math. Mech. 16 (1966) 1–16.
[3] A.C. Eringen, Theory of thermomicrofluids, J. Math. Anal. Appl. 38 (1972) 480–496.
[4] T. Ariman, M.A. Turk, N.D. Sylvester, Micro continuum fluid mechanics––A review, Int. J. Eng. Sci. 11 (1973)
905–930.
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