An investigation 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), k0
(permeability parameter), M (Hartmann number) and w (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 k0, 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. It is observed that the magnitude of the secondary
velocity profiles increases whenever there is an increase in either of the
Grashof number or the modified Grashof number for mass transfer or the
permeability of the porous media. Concentration profiles decreases with an
increase in the Schmidt number.