Heat and Mass Transfer by MHD Stagnation-Point Flow of a Power-Law Fluid towards a Stretching Surface with Radiation, Chemical Reaction and Soret and Dufour Effects

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.

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.


Author(s):  
Naramgari Sandeep ◽  
Chalavadi Sulochana ◽  
Isaac Lare Animasaun

With every passing day the heat transfer enhancement in the convectional base fluids plays a major role in several industrial and engineering processes. During these process nanofluids has attained its great importance to enhance the heat transfer rate in the convectional flows. Keeping this into view, in this study we investigated the stagnation point flow, heat and mass transfer behaviour of MHD Jeffrey nanofluid over a stretching surface in the presence of induced magneticfield, non-uniform heat source or sink and chemical reaction. Using similarity technique, the governing boundary layer partial differential equations are transformed into nonlinear coupled ordinary differential equations. The ordinary differential equations are solved numerically using Runge-Kutta-Felhberg scheme. An excellent agreement of the present results has been observed with the existed literature under some special cases. The effects of various dimensionless governing parameters on velocity, induced magneticfield, temperature and nanoparticle concentration profiles are discussed and presented through graphs. Also, friction factor, local Nusselt and Sherwood numbers are computed and discussed. Dual solutions are presented for suction and injection cases. It is found that dual solutions exist only for certain range of suction or injection parameter. It is also observed that an increase in the heat and mass transfer rate for higher values of Deborah number.


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