Mhd Free and Forced Convection Flow of Newtonian Fluid through a Porous Medium in an Infinite Vertical Plate in Presence of Thermal Radiation Heat Transfer and Surface Temperature Oscillation

In this paper, we study the steady and unsteady magneto hydro dynamic (MHD) viscous, incompressible free and forced convective flow of an electrically conducting Newtonian fluid through a porous medium in the presence of appreciable thermal radiation heat transfer and surface temperature oscillation taking hall current into account. The fluid is assumed to be optically-thin and magnetic Reynolds number small enough to neglect induced hydro magnetic effects. Secondary (cross-flow) effects are incorporated. The governing equations are solved analytically using complex variables. Detailed computations of the influence of governing parameters on the unsteady mean flow velocity (u1) and unsteady mean cross flow velocity (w1), the plate shear stresses for the unsteady main and the secondary flow and also temperature gradients due to the unsteady main flow and the unsteady cross flow, are presented graphically and tabulated. The closed-form solutions reveal that the shear stress component due to a steady mean flow experiences a non-periodic oscillation which varies as a function of the Hartmann number (M) and radiation parameter (K1). However the shear stress components due to main and cross flows for an unsteady mean flow are subjected to periodic oscillation which depends on Hartmann number, inverse Darcy parameter, radiation parameter but also on the Prandtl number and frequency of oscillation. Applications of the model include fundamental magneto-fluid dynamics, MHD energy systems and magneto-metallurgical processing for aircraft materials.