Impacts of time varying wall temperature and concentration on MHD free convective flow of a rotating fluid due to moving free-stream with hall and ion-slip currents

Abstract

Present paper mathematically discusses unsteady MHD free convection flow of thermally conducting, chemically reacting, and rotating fluid over a vertical plate due to moving free-stream. The applied magnetic field is considered to be strong enough to generate Hall and ion-slip currents. The wall temperature and concentration are considered to be linearly varying with time. Laplace transform technique is successfully implemented to solve the resulting partial differential equations representing the fluid motion. The expression for fluid velocity is derived in four special cases., i.e. (i) for those fluids whose viscosity, thermal diffusivity and molecular diffusivity are not of same order of magnitude, (ii) for those fluids whose viscosity and thermal diffusivity are of same order of magnitude while molecular diffusivity is of different order, (iii) for those fluids whose viscosity and molecular diffusivity are of same order of magnitude while thermal diffusivity is of different order, and (iv) for those fluids whose viscosity, thermal diffusivity and molecular diffusivity are of same order of magnitude. To discuss the specific features of the flow, numerical computation is carried out. The variations in fluid velocity, fluid temperature and concentration are presented through graphs whereas skin friction coefficient, rate of heat and mass transfer are presented in tables. A notable observation recorded that in the absence of thermal buoyancy force there appears reverse flow in the secondary flow direction while in the absence of concentration buoyancy force there does not exists reverse flow in the secondary flow direction.