The Influence Of Slip Conditions, Wall Properties And Heat Transfer On Peristaltic Pumping Of A Bingham Fluid S. Dhananjaya Dept. of Mathematics Sri Venkateswara University Tirupati, (A.P) India. P.V. Arunachalam Dept. of Mathematics Sri Venkateswara University Tirupati, (A.P) India. S. Sreenadh Dept. of Mathematics Sri Venkateswara University Tirupati, (A.P) India. P. Lakshminarayana Dept. of Mathematics Sree Vidyanikethan Engineering College Tirupati, (A.P) India. Abstract The effects of both wall slip conditions and heat transfer on the peristaltic flow of a Bingham fluid in a porous channel with elastic wall properties have been investigated under the assumptions of long wavelength and low Reynolds number. The expressions for velocity, temperature, stream function and heat transfer coefficient are obtained. The effects of various physical parameters on velocity and temperature are analyzed through graphs and the results are discussed in detail. Keywords: Peristaltic flow, Slip conditions, Wall properties, Heat transfer, Bingham fluid and Non- uniform channel. 1. Introduction: Peristaltic transport is a mechanism of fluid transport induced by a progressive wave of area contraction or expansion along the length of a distensible tube, mixing and transporting the fluid in the direction of the wave propagation. It occurs widely in many biological and biomedical systems. It plays an important role in transporting many physiological fluids in the body in various situations such as swallowing food through the oesophagus, urine transport from the kidneys to the urinary bladder through the ureter, movement of chyme in the gastrointestinal tract, the transport of spermatozoa in the ductus efferentes of the male reproductive tract and in the cervical canal etc. It has many applications in medicine and industry. Also the literature on peristalsis is extensive. Some investigations [1-7] are presented in the references. Most of the biofluids like blood are observed to behave like non-Newtonian fluids. In fact there is no unique model to describe all non-Newtonian fluids in physiological systems, several models are proposed [8-18] to explain the behavior of these biofluids. Several researchers studied the peristaltic flow with heat transfer due to its wide applications in fluid mechanics. Vajravelu et al. [19] analyzed the peristaltic flow and heat transfer in a vertical porous annulus with long wavelength approximation. Srinivas and Kothandapani [20] studied the influence of heat and mass transfer on MHD peristaltic flow through porous space with compliant walls. Mekheimer and Abd Elmaboud [21] investigated the influence of heat transfer and magnetic field on the peristaltic transport of a Newtonian fluid in a vertical annulus. Srinivas et al. [22] studied the influence of slip conditions, wall properties and heat transfer on MHD peristaltic transport. The influence of heat transfer on the peristaltic transport of a Jeffrey fluid in a vertical porous stratum is discussed by Vajravelu et al. [23]. Rathod and Laxmi [24] examined the effects of heat transfer on the peristaltic MHD flow of a Bingham fluid through a porous medium in a channel. 1 In several applications the flow pattern corresponds to a slip flow, the fluid presents a loss of adhesion at the wetted wall making the fluid slide along the wall. When the molecular mean free path length of the fluid is comparable to the distance between the plates as in nanochannels or microchannels, the fluid exhibits noncontinuum effects such as slip-flow as demonstrated experimentally by Derek et al. [25]. Hron et al. [26] have presented analytical solutions for the flows of a generalized fluid of complexity two in special geometries under the assumption that the flows meet Navier slip conditions at the boundary. Ali et al. [27] have studied the slip effects on the peristaltic transport of MHD fluid with variable viscosity. Ebaid [28] studied the effects of magnetic field and wall slip conditions on the peristaltic transport of a Newtonian fluid in an asymmetric channel. Arun Kumar et al. [29] have investigated the influence of partial slip on the peristaltic transport of a micropolar fluid in an inclined asymmetric channel. Hayat et al. [30] have investigated the MHD peristaltic channel flow of a Jeffrey fluid with complaint walls and porous medium. The interaction of peristalsis with heat transfer for the motion of a viscous incompressible Newtonian fluid in a channel with wall effects has been studied by Radhakrishnamacharya and Srinivasulu [31]. In the present study the effects of both wall slip conditions and heat transfer on peristaltic flow of a Bingham fluid in a porous channel with elastic wall properties have been analyzed under the assumptions of long wavelength and low-Reynolds number. The expressions for velocity, temperature, stream function and heat transfer coefficient are obtained. The effects of various physical parameters on velocity and temperature are analyzed through graphs and the results are discussed in detail. 2. Mathematical formulation Consider the flow of a Bingham fluid through a two-dimensional channel of uniform thickness. The walls of the channel are assumed to be flexible and are taken as stretched membranes, on which travelling sinusoidal waves of moderate amplitude are imposed. The geometry of the wall surface is given by 2 (1) ( x, t ) d ( x) a Sin x ct where d ( x) d m x, m 1 The governing equations which describe the flow are u v 0 x y t u (2) p 2 u u v u 2 ( 0 ) x y x y x y (3) t u 2 v 2 v p v v 2 2 x x y y y (4) t u k 2 2 v T ( )T x 2 y 2 x y u 2 v 2 v u 2 2 x y x y where (5) u , v , , , p , d , a , , c, m , , , k , T and 0 are the axial velocity, transverse velocity, fluid density, viscosity of the fluid, pressure, mean width of the channel, amplitude, wavelength, wave speed, dimensional non-uniformity of the channel, specific heat at constant volume, kinematic viscosity, thermal conductivity of the fluid, temperature and yield stress. The equation of motion of the flexible wall is expressed as 2 L* ( ) p p0 m d a m , , , 1 mx sin 2 ( x t ), d d d 2 (T T0 ) cd c R , , Pr , Ec , (T1 T0 ) k (T1 T0 ) m1cd 3 d 3 cd 3 h E1 3 , E2 3 , E3 2 , c d (11) where R is the Reynolds number, and are the dimensionless geometric x y d2 p ct k x , y , , p , t ,K 2 , d cd c d (6) where L* is an operator, which is used to represent the motion of stretched membrane with viscosity damping forces such that 2 L* x 2 m1 2 t 2 C t (7) where is the elastic tension in the membrane, m1 is the mass per unit area, C is the coefficient of viscous damping forces, p0 is the pressure on the out side surface of the wall due to the tension in the muscles and h is the dimensional slip parameter. We assumed p0 0 . parameters, Pr is the Prandtl number, Ec is the Eckert number, E1 , E2 and E3 are the dimensionless elasticity parameters m is the non-uniform parameter and is the Knudsen number (slip parameter) . Continuity of stress at y and using x- momentum equation, yield * p 2 u u L ( ) 2 ( 0 ) x x y x y Using non-dimensional quantities the basic equations (1) - (10) reduce to u v u x y t 2 2 2 p R 2 x t y y xy x y 3 2 2 2 ( 0 2 ) x y y y (8) u h u at y y T 0 on y y0 y T T1 on y (9) (12) 2 2 2 p R 3 2 x xy y t y y x (10) 3 3 2 2 x 3 yy 2 Introducing such that (13) u y and v x and the following parameters are given by 1 2 2 2 R 2 2 y t y x x y Pr x 2 2 2 2 2 2 2 E 4 2 x 2 xy y non-dimensional (14) 2 at y y y (15) 2 3 3 2 ( 0 ) x 2 y y y 2 (24) and corresponding plug flow velocity is given by 1 u p A ( y0 2 y0 y0 ) ( y02 2 2 ) 2 (25) where y0 0 A and E A 8 3 ( E1 E2 ) cos 2 ( x t ) 3 sin 2 ( x t ) 2 2 2 2 R y xy x y 2 t y 3 3 2 E1 E2 E3 3 xt 2 xt x (16) Further, it is assumed that the zero value of the streamline at the line y = 0, i.e. p (0) 0, yy (0) 0 at y 0 (17) 0 on y y0 y 1on y 1 p A ( y0 2 y0 y0 ) ( y02 2 2 ) y 2 2 and the stream function in the non-plug (18) flow region as ( y 2 y0 2 ) 0 ( y y0 ) ( y y0 ) 2 3. Solution of the problem y 3 8 y03 2 y A y y02 ( ) 2 6 (26) The corresponding velocity in the nonplug flow region is given by A u 0 ( y ) ( y 2 2 2 ) 2 (27) Applying the long wavelength and low Reynolds number approximation, the basic equations (12) - (18) reduce to p 2 (19) 0 0 2 x y y p (20) y Equation (20) shows that p is not a function of y 1 2 2 (21) 0 E( ) 2 0 Using equation (26) in equation (21) subject to the condition (18) we obtain the temperature as y 3 A2 y 4 0 Ay 3 Br 0 2 C1 y C2 6 12 3 (28) 2 2 3 y A y0 where C1 Br 0 2 0 0 Ay0 2 2 3 Pr y y By differentiating equation (19) with respect y we obtain 2 2 (22) 0 2 0 y 2 y From equation (16) we get 3 2 3 2 ( 0 2 ) E1 3 E2 E3 y y xt 2 xt x (23) By solving equation (22) with boundary conditions (15), (17) and (23) we obtain 2 3 A2 4 3 C2 1 Br 0 0 A C1 6 12 3 and Br Ec Pr is the Brinkman number The coefficient of heat transfer at the wall the stream function in the plug flow region is given by Nu y at y as (29) 4 number Br. non-uniform parameter m , amplitude ratio and yield stress parameter 0 can be examined through the figures Fig.9 - Fig.12. It is noticed that due to peristalsis, the rate of heat transfer ( Nu ) shows oscillatory behaviour. From Fig.9 we observe that the Nusselt number increases with increasing Brinkman number Br . Figures Fig.10 to Fig.12 depict that the Nusselt number increases with increasing non-uniform parameter m , amplitude ratio and yield stress parameter 0 . 4. Results and Discussions Equation (27) gives the expression for velocity as a function of y. Velocity profiles are plotted from Fig.1 to Fig.4 to study the effects of different parameters such as slip parameter , non-uniform parameter m , amplitude ratio and yield stress parameter 0 on the velocity distribution. Fig.1 is plotted for different values of slip parameter . It is observed that the velocity profiles are parabolic and the velocity increases with increasing . Fig.2 depicts that the velocity for a divergent channel (m > 0) is higher compared with uniform channel (m = 0) where as it is lower for a convergent channel (m < 0). From Fig.3 and Fig.4 we noticed that the velocity increases with increasing amplitude ratio and decreasing yield stress parameter 0 . Equation (28) gives the expression for temperature as a function of y. Temperature profiles are plotted from Fig.5 to Fig.8 to study the effects of different parameters such as non-uniform parameter m , Brinkman number Br , amplitude ratio and yield stress parameter 0 on the temperature distribution. It is observed that the temperature profiles are almost parabolic. Fig.5 reveals that the temperature is higher diverging channel (m > 0) compared with uniform (m = 0) and convergent (m < 0) channels. Fig.6 and Fig.7 are plotted to study the effect of Brinkman number Br and amplitude ratio . We notice that the temperature increases with increasing Brinkman number Br and amplitude ratio . Fig.8 shows that the temperature decreases with increasing yield stress parameter 0 . The rate of heat transfer ( Nu ) is calculated in equation (29). The variation in Nusselt number for different values of the interesting parameters Brinkman Trapping phenomenon Trapping is an interesting phenomenon which refers to closed circulating streamlines that exist at every high flow rates and when occlusions are very large. Streamlines are plotted to study the effect of slip parameter and non-uniform parameter m on trapping through Fig.13 and Fig.14. From Fig.13 we observe that the number of trapped boluses increases with increasing slip parameter. Fig.14 reveals that the number of trapped boluses increases with increasing non-uniform parameter. 5 Fig.1 Velocity profiles for different ' 'with fixed y0 = 0.2, Fig. 4 Velocity profiles for different ' 0 'with fixed x = 0.2,t = 0.1, x = 0.2,t = 0.1,m = 0.1,Br = 2, 0.1, E1 = 0.5,E 2 = 0.3,E3 = 0.2 = 0.1, = 0.1,Br = 2, m 0.1, E1 = 0.5,E 2 = 0.3,E3 = 0.2 Fig.2 Velocity profiles for different 'm 'with fixed y0 = 0.2,x = 0.2, Fig.5 Temperature profiles for different 'm ' with fixed y0 = 0.2, x = 0.2,t = 0.1,Br = 2, 0.1, E1 = 0.3,E 2 = 0.2,E3 = 0.1, t = 0.1, = 0.1,Br = 2, 0.1, E1 = 0.5,E 2 = 0.3,E3 = 0.2 Fig. 3Velocity profiles for different ' ' with fixed y0 = 0.2,x = Fig.6 0.2, Temperature profiles for different 'Br ' with fixed y0 = 0.2, t = 0.1, = 0.1,Br = 2, m 0.1, E1 = 0.5,E 2 = 0.3,E 3 = 0.2 6 x = 0.2,t = 0.1.m=0.1, 0.1, E1 = 0.3,E 2 = 0.2,E3 = 0.1, Fig. 7 Temperature profiles for different ' ' with fixed y0 = 0.2, x = 0.2,t = 0.1.m=0.1, Br 2, E1 = 0.3,E 2 = 0.2,E 3 = 0.1, Fig. 8Temperature profiles for different ' 0 ' with fixed Br 2, x = 0.2,t = 0.1.m=0.1, 0.1, E1 = 0.3,E 2 = 0.2,E3 = 0.1, Fig. 10Variation of Nu for different 'm'with fixed x = 0.2, t = 0.1.Br=2, 0 0.1, 0.05, E1 = 0.2,E 2 = 0.1,E3 = 0.1, Fig. 11Variation of Nu for different ' ' with fixed x = 0.2, t = 0.1.m=0.1, 0 0.1, Br 2, E1 = 0.2,E2 = 0.1,E3 = 0.1, Fig.12 Variation of Nu for different ' 0 ' with fixed x = 0.2, Fig. 9Variation of Nu for different 'Br 'with fixed x = 0.2, t = 0.1.m=0.1, 0 0.1, 0.05, E1 = 0.2,E2 = 0.1,E3 = 0.1, t = 0.1.m=0.1,Br 2, 0.05, E1 = 0.2,E 2 = 0.1,E 3 = 0.1, 7 8 (a) (a) (b) (b) (c) (c) Fig.13 Stream lines for (a) 0,(b) 0.4,(c) 0.6, y0 0.1, m 0.1,t 0.5, 0.2, E1 = 0.6,E2 = 0.4,E3 = 0.2 8 Fig.14 Stream lines for (a)m 0.2,(b)m 0,(c)m 0.2, y0 0.1, 0.2,t 0.5, 0.2, E1 = 0.6,E2 = 0.4,E3 = 0.2 References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Shapiro, A.H., Jaffrin, M.Y. and Weinberg, S.L., 1969 Peristaltic pumping with long wavelength at low Reynolds number. 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