Available online at www.pelagiaresearchlibrary.com Pelagia Research Library Advances in Applied Science Research, 2015, 6(8):67-81 ISSN: 0976-8610 CODEN (USA): AASRFC 67 Pelagia Research Library Soret and Dufour effects on MHD mixed convective heat and mass transfer flow with thermophoresis past a vertical flat plate embedded in a saturated porous medium in the presence of radiation and viscous dissipation S. Jagadha 1 and Naikoti Kishan 2 1 Department of Mathematics, St. Martin’s Engineering College, Dhullapally, Secunderabad, Telangana, India 2 Department of Mathematics, University College of Science, Osmania University, Hyderabad, India _____________________________________________________________________________________________ ABSTRACT The effects of Soret and Dufour and MHD on Darcy-Forchheimer mixed convection flow with heat and mass transfer from a vertical flat plate embedded in a saturated porous medium taking into the influence thermophoresis, viscous dissipation and radiation. The fluid is considered in a grey medium and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. A similarity solution for the transformed governing equations is obtained. The coupled non-linear ordinary equations are linearized by using Quasi-linearization technique. The governing coupled ordinary differential equations are being solved by employing an implicit finite difference scheme. Numerical computation are carried out for the non dimensional physical parameters. The results are analyzed for the effect of different physical parameters, such as radiation R, Soret number S r , Dufour D f , Viscous dissipation Ec, mixed convection parameter Ra x /Pe x , buoyancy ratio N, inertia parameter Λ, magnetic field parameter Ha, Prandtl number Pr, Lewis number Le, Schmidt number Sc and thermophoretic parameter τ. Keywords: Soret and Dufour, Darcy-Forchheimer, Radiation, MHD, Finite difference method and mixed convection. _____________________________________________________________________________________________ INTRODUCTION Mixed convective heat and mass transfer flow is very important in manufacturing industries for the design of reliable equipment, nuclear plants, gas turbines, and various propulsion devices for aircraft, missiles, satellites, and space vehicles. In light of these various applications, the unsteady MHD combined convection over a moving vertical sheet in a fluid saturated porous medium with uniform surface heat flux was studied by El-Kabeira et.al [1]. Mixed convection on bodies embedded in a non-Darcian porous medium have been extensively studied and reported for flow driven by temperature variations only [2,3,4,5,]. The problem of Darcy–Forchheimer mixed convection heat and mass transfer in fluid-saturated porous media was studied by Rami et al. [6]. Goren [7] was one of the first to study the role of thermophoresis in the laminar flow of a viscous and incompressible fluid. Most previous studies of the same problem neglected viscous dissipation and thermophoresis. But Gebhart [8] has shown that the viscous dissipation effect plays an important role in natural convection in various devices that are subjected to large variations of gravitational force or that operate at high rotational speeds. Motivated by the above investigations and possible applications. Small particles, such as dust, when suspended in a gaseous medium possessing a temperature gradient, it will move in the direction opposite to the temperature gradient. This motion is known as thermophoresis, occurs because gas