International Journal of Scientific and Research Publications, Volume 3, Issue 6, June 2013 1 ISSN 2250-3153 www.ijsrp.org Radiation and Mass Transfer Effects on MHD Free Convective Flow of a Micropolar Fluid past an Infinite Vertical Porous Moving Plate Embedded in a Porous Medium with Viscous Dissipation P. Roja a , T. Sankar Reddy b and N. Bhaskar Reddy c a Dept. of Humanities and Sciences, K.O.R.M Engineering college, Kadapa, Y.S.R.(Dt) -516003, A.P, INDIA. b Dept. of Science and Humanities, Annamacharya Institute of Technology & Sciences, C. K Dinne, Kadapa, Y.S.R (Dt) -516003, A.P, INDIA. c Dept. of Mathematics, Sri Venkateswara University, TIRUPATI – 517502, A.P. Abstract- The objectives of the present study are investigate the unsteady two-dimensional laminar flow of a viscous dissipative micropolar fluid past a semi-infinite, vertical porous plate moving steadily and subjected to a thermal radiation and mass transfer. The plate moves with constant velocity in the longitudinal direction and free stream velocity follows an exponentially small perturbation law. The Rosseland approximation is used to describe radiative heat transfer in the limit of optically thick fluids. The method of solution can be applied for small perturbation approximation. Numerical results of velocity profiles of micropolar fluids are compared with the corresponding flow problems for a Newtonian fluid. Also, the results of the skin friction coefficient, the couple stress coefficient, the rate of heat and mass transfers at the wall are prepared with various values of the fluid properties and flow conditions. Index Terms- Radiation; Mass transfer; MHD; Micropolar fluid; Porous medium; Viscous dissipation. Nomenclature: A suction velocity parameter C concentration.. f C skin friction coefficient. m C couple stress coefficient p C specific heat at constant pressure . D chemical molecular diffusivity Ec Eckert number g acceleration due to gravity. Gc modified Grashof number. Gr Grashof number. j microinertia per unit mass. k thermal conductivity n parameter related to microgyration vector and shear stress. Nu Nusult number. p pressure. Pr Prandtl number. Re x local Reynolds number R Radiation parameter Sc Schmidt number. Sh Sherwood number. t time. T temperature. , uv components of velocities along and perpendicular to the plate. 0 U scale of free stream velocity. 0 V scale of suction velocity. , xy distances of along and perpendicular to the plate. Greek symbols  fluid thermal diffusivity  ratio of vertex viscosity and dynamic viscosity c  coefficient of volumetric expansion with concentration f  coefficient of volumetric expansion of the working fluid  spin gradient viscosity  scalar constant  scalar constant   1   dimensionless temperature  coefficient of vertex(microrotation) viscosity  fluid dynamic viscosity  fluid density  electrical conductivity.  fluid kinematic viscosity r  fluid dynamic rotational viscosity  friction coefficient  angular velocity vector Subscripts w wall condition  free steam condition Superscripts  ' differentiation with respect to y.  dimensional properties