International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 2, Issue 2, May- July (2011), © IAEME 99 UNSTEADY MHD FREE CONVECTIVE FLOW IN A ROTATING POROUS MEDIUM WITH MASS TRANSFER Dr. Sundarammal Kesavan 1 , Supervisor, SRM University, Chennai M. Vidhya 2 , Research Scholar, SRM University, Chennai Dr. A. Govindarajan 3 sundarammalkesavan@ktr.srmuniv.ac.in , mvidhya_1978@yahoo.co.in , govindarajana@ktr.srmuniv.ac.in ABSTRACT An exact analysis of unsteady MHD free convective flow and mass transfer during the motion of a viscous incompressible fluid through a porous medium, bounded by an infinite vertical porous surface, in a rotating system is presented. The porous plane surface and the porous medium are assumed to rotate in a solid body rotation. The vertical surface is subjected to uniform constant suction perpendicular to it and the temperature at this surface fluctuates in time about a non-zero constant mean. Analytical expressions for the velocity, temperature and concentration fields are obtained using the perturbation technique. The effects of R (rotation parameter), k 0 (permeability parameter), M (Hartmann number) and ω (frequency parameter) on the flow characteristics are discussed. It is observed that the primary velocity component decreases with the increase in either of the rotation parameter R, the permeability parameter k 0 , or the Hartmann number M. It is also noted that the primary skin friction increases whenever there is an increase in the Grashof number Gr or the modified Grashof number Gm. It is clear that the heat transfer coefficient in terms of the Nusselt number decreases in the case of both air and water when there is an increase in the Hartmann number M. Keywords: Mass transfer, free convection, porous medium, MHD, rotation. 1. INTRODUCTION Free convection flows are of great interest in a number of industrial applications such as fiber and granular insulation, geothermal systems, etc. Buoyancy is also of importance in an environment where differences between land and air temperatures can give rise to complicated flow patterns. Magnetohydrodynamic (MHD) flows have attracted the attention of a large number of scholars due to their diverse applications. In astrophysics and geophysics, they are applied to study the stellar and solar structures, interstellar matter, radio propagation through the ionosphere, etc. In engineering, MHD flows find their application in MHD pumps, 1 Professor in Department of Mathematics, SRM University, Kattankulathur, Tamil Nadu, 603 203, India 2 Senior Lecturer, Dept of mathematics Sathyabama University, Rajiv Gandhi Road, Chennai 600 119 3 Professor, Department of Mathematics, SRM University, Kattankulathur, Tamil Nadu, 603 203, India International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print) ISSN 0976 – 6359(Online) Volume 2 Issue 2, May – July (2011), pp. 99-110 © IAEME, http://www.iaeme.com/ijmet.html IJMET © I A E M E