Abstract
The study of unsteady hydrodynamic free convective flow of a viscous incompressible fluid past a vertical porous plate in the presence of a variable suction has been made. Approximate solutions have been derived for the velocity and temperature fields, shear stress, and rate of heat transfer using perturbation technique. It is observed that main fluid velocity decreases with increase in Prandtl number, while it increases with increase in suction parameter. The cross-velocity decreases near the plate and increases away from the plate with increase in suction parameter. On the other hand, it increases near the plate and decreases away from the plate with increase in frequency parameter. The amplitude and the tangent of phase shift of the shear stress due to main flow decrease with increase in either Prandtl number, Grashof number, or frequency parameter. It is seen that the temperature decreases with increase in either suction parameter, Prandtl number, or frequency parameter. It is also seen that the amplitude of the rate of heat transfer increases and the tangent of phase shift of rate of heat transfer decreases with increase in Prandtl number.