Abstract
The unsteady flow of a viscous electrically conducting fluid bounded by a porous disk in the presence of a uniform magnetic field has been studied. Exact analytic solution for the flow generated by arbitrary periodic oscillation of a porous disk is obtained. Some interesting flows caused by certain special oscillations are also examined. Asymptotic analysis is carried out to determine the solutions for the large time. The structure of the velocity boundary layers is discussed physically. In the case of blowing and resonance, the hydromagnetic steady state flow is found to exist.