Effects of plate temperature oscillation on the unsteady free convective flow of an incompressible, electrically conducting fluid along a semi-infinite vertical porous plate subjected to a transverse magnetic field in the presence of a first order chemical reaction and thermal radiation is studied. An improved computational method is employed to the prevailing analytic technique of computation for the unsteady part of the velocity, temperature and concentration. Results are obtained for the

more »

... steady flow and the unsteady flow for the velocity, temperature, concentration .Tabulated values for the mean Skin friction, mean heat transfer and mean mass transfer ,phases of transient velocity, temperature and concentration, amplitude and phases of Skin Friction, coefficient of heat transfer and coefficient of mass transfer are presented. Graphical results for the mean flow and the transient flow are displayed for various values of the magnetic, chemical reaction, radiation and suction parameter. INTRODUCTION Free convection arises in the fluid when temperature changes cause density variation leading to buoyancy forces acting on the fluid elements. The most common example of free convection is the atmospheric flow which is driven by temperature differences. Sometimes along with the free convection currents caused by difference in temperature the flow is also affected by the differences in concentration or material constitution. This type of flow has applications in many branches of science and engineering. The study of such flow under the influence of magnetic field has attracted the interest of many investigators in view of its application in MHD generators, plasma studies, nuclear reactors, geothermal energy extractions and boundary layer control in the field of aerodynamics (Gholizadeh, 1990; Muthucumaraswamy, 2006; Chaudhury, 2007; Alam et al., 2009) have studied such flows. In several processes involving high temperature such as space and nuclear technologies, radiation effects are very common and this changes the behavior of the boundary layer flow considerably. The inclusion of radiation effects in the energy equation leads to a highly nonlinear partial differential equation. The radiative heat flux term in the energy equation can be simplified to a great extent by invoking the Rosseland diffusion approximation which provides one of the most straight forward simplifications of the differential equations governing such flows by considering the optically thick radiation limit.