International Journal of Engineering and Technical Research (IJETR) ISSN: 2321-0869, Volume-2, Issue-11, November 2014 210 www.erpublication.org RADIATION AND MASS TRANSFER EFFECTS ON UNSTEADY MHD FREE CONVECTIVE FLOW PAST A VERTICAL POROUS PLATE EMBEDDED IN A POROUS MEDIUM IN A SLIP FLOW REGIME WITH HEAT SOURCE/SINK AND SORET EFFECT B Lavanya & A Leela Ratnam Abstract —In the present analysis, we study the two-dimensional unsteady MHD free convection laminar heat and mass transfer flow past a semi-infinite vertical porous plate embedded in a porous medium in a slip flow regime in presence of thermal radiation, heat source/sink and Soret effects. A magnetic field of uniform strength is assumed to be applied transversely to the direction of the main flow. Perturbation technique is applied to transform the non-linear coupled governing partial differential equations in dimensionless form into a system of ordinary differential equations. The equations are solved analytically and the solutions for the velocity, temperature and concentration fields are obtained. The effects of various flow parameters on velocity, temperature and concentration fields are presented graphically. For different values of the flow parameters involved in the problem, the numerical calculations for the skin-friction coefficient, Nusselt number and Sherwood number at the plate are performed in tabulated form. Index Terms— MHD, skin-friction coefficient Introduction, Magnetohydrodynamic. I. INTRODUCTION Natural convection flow over vertical surfaces immersed in porous media has paramount importance because of its potential applications in soil physics, geohydrology, and filtration of solids from liquids, chemical engineering and biological systems. Ostrach [1], the initiator of the study of convection flow, made a technical note on the similarity solution of transient free convection flow past a semi-infinite vertical plate by an integral method. Study of fluid flow in porous medium is based upon the empirically determined Darcy’s law. Such flows are considered to be useful in diminishing the free convection, which would otherwise occur intensely on a vertical heated surface. Study of flow problems through porous medium is heavily based on Darcy’s experimental law [2]. Wooding [3] and Brink- man [4,5] have modified Darcy’s law, which are used by many authors on study of convective flow in porous media. Many transport processes exist in nature and in industrial applications in which the simultaneous heat and mass transfer occur as a result of combined buoyancy effects of thermal diffusion and diffusion of chemical species. Manuscript received November 18, 2014. B Lavanya, Assistant professor in the department of Mathematics at Priyadarshini college of Engineering and Technology in Nellore. A Leela Ratnam, Professor in Mathematics Department at Sri Padmavathi Mahila Viswavidyalam Tirupathi. A few representative fields of interest in which combined heat and mass transfer plays an important role are designing of chemical processing equipment, formation and dispersion of fog, distribution of temperature and moisture over agricultural fields and groves of fruit trees, crop damage due to freezing, and environmental pollution. In this context, Soundalgekar [ 7] extended his own problem of Soundalgekar [6 ] to mass transfer effects. Callahan and Marner [8] considered the transient free convection flow past a semi- infinite vertical plate with mass transfer. Unsteady free convective flow on taking into account the mass transfer phenomenon past an infinite vertical plate was studied by Soundalgekar and Wavre [9]. Magnetohydrodynamic flows have many applications in solar physics, cosmic fluid dynamics, geophysics and in the motion of earth’s core as well as in chemical engineering and electronics. Verma and Srivastava [10] proposed the effect of magnetic field on unsteady blood flow through a narrow tube. Huges and Young [11] gave an excellent summary of applications. MHD free convective flow of an electrically conducting fluid between two heated parallel plates in the presence of induced magnetic field by using analytical solution was carried out by Sharma [12]. Chakrabarti and Gupta [13 ] explained the heat transfer effect on hydromagnetic flow over a stretching sheet. Convective heat transfer effect on MHD flow past a continuously moving plate embedded in a non-Darcian porous medium has been proposed by Abo-Eldahab and El-Gendy [14 ]. Radiation is a process of heat transfer through electromagnetic waves. Radiative convective flows are encountered in countless industrial and environmental process. For example, heating and cooling chambers, fossil fuel combustion energy processes, evaporation from large open water reservoirs, astrophysical flows etc. Radiative heat and mass transfer play an important role in space related technology. The effect of radiation on various convective flows under different conditions have been studied by many researchers including Hussain and Thakar [15], Ahmed and Sarmah [16], Rajesh and Varma [17], Pal and Mondal [18], Samad and Rahman [19], Karthikeyan et al. [20], Das et al. [21] and Pal et al. [22]. The study of heat source/sink effects on heat transfer is very important because its effects are crucial in controlling the heat transfer. Radiation effects on unsteady MHD flow through a porous medium with variable temperature in presence of heat source/sink is studied by Vijaya Kumar et al.