scholarly journals Heat Transfer due to Magnetohydrodynamic Stagnation-Point Flow of a Power-Law Fluid towards a Stretching Surface in the Presence of Thermal Radiation and Suction/Injection

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Tapas Ray Mahapatra ◽  
Sabyasachi Mondal ◽  
Dulal Pal

An analysis is made on the study of two-dimensional MHD (magnetohydrodynamic) boundary-layer stagnation-point flow of an electrically conducting power-law fluid over a stretching surface when the surface is stretched in its own plane with a velocity proportional to the distance from the stagnation-point in the presence of thermal radiation and suction/injection. The paper examines heat transfer in the stagnation-point flow of a power-law fluid except when the ratio of the free stream velocity and stretching velocity is equal to unity. The governing partial differential equations along with the boundary conditions are first brought into a dimensionless form and then the equations are solved by Runge-Kutta fourth-order scheme with shooting techniques. It is found that the temperature at a point decreases/increases with increase in the magnetic field when free stream velocity is greater/less than the stretching velocity. It is further observed that for a given value of the magnetic parameter M, the dimensionless rate of heat transfer at the surface and |θ′(0)| decreases/increases with increase in the power-law index n. Further, the temperature at a point in the fluid decreases with increase in the radiation parameter NR when free stream velocity is greater/less than the stretching velocity.

2015 ◽  
Vol 13 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Swati Mukhopadhyay

Abstract This paper presents the magnetohydrodynamic (MHD) boundary layer stagnation point flow with diffusion of chemically reactive species undergoing first-order chemical reaction over a permeable stretching sheet in presence of partial slip. With the help of similarity transformations, the partial differential equations corresponding to momentum and the concentration equations are transformed into non-linear ordinary differential equations. Numerical solutions of these equations are obtained by shooting method. It is found that the horizontal velocity increases with the increasing value of the ratio of the free stream velocity and the stretching velocity. Velocity decreases with the increasing magnetic parameter when the free-stream velocity is less than the stretching velocity but the opposite behavior is noted when the free-stream velocity is greater than the stretching velocity. Due to suction, fluid velocity decreases at a particular point of the surface. With increasing velocity slip parameter, velocity increases when the free-stream velocity is greater than the stretching velocity. But the concentration decreases in this case. Concentration decreases with increasing mass slip parameter.


Author(s):  
S. M. M. EL-Kabeir ◽  
Ali Chamkha ◽  
A. M. Rashad

The thermal-diffusion and diffusion-thermo effects on heat and mass transfer by magnetohydrodynamic (MHD) mixed convection stagnation-point flow of a power-law non-Newtonian fluid towards a stretching surface in the presence of a magnetic field, thermal radiation and homogenous chemical reaction effects have been studied. A suitable set of dimensionless variables is used and similar equations governing the problem are obtained. The resulting equations have the property that they reduce to various special cases previously considered in the literature. An adequate implicit tri-diagonal finite-difference scheme is employed for the numerical solution of the obtained equations. Various comparisons with previously published work are performed and the results are found to be in excellent agreement. Representative results for the velocity, temperature, and concentration profiles as well as the local skin-friction coefficient, the local Nusselt number and the local Sherwood number illustrating the influence of the magnetic parameter, power-law fluid index, mixed convection parameter, concentration to thermal buoyancy ratio, thermal radiation, chemical reaction, and Dufour and Soret numbers are presented and discussed.


2006 ◽  
Vol 11 (2) ◽  
pp. 187-197 ◽  
Author(s):  
G. C. Layek ◽  
S. Mukhopadhyay ◽  
SK. A. Samad

An analysis is performed to investigate the structure of the boundary layer stagnation‐point flow and heat transfer of a fluid through a porous medium over a stretching sheet. A scaling group of transformations is applied to get the invariants. Using the invariants, a third and a second order ordinary differential equations corresponding to the momentum and energy equations are obtained respectively. The equations are then solved numerically. It is found that the horizontal velocity increases with the increasing value of the ratio of the free stream velocity (ax) and the stretching velocity (ax). The temperature decreases in this case. At a particular point of the stretching sheet, the fluid velocity decreases or increases with the increase of the permeability of the porous medium when the free stream velocity is less or grater than the stretching velocity.


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