Exact solution of an oscillatory MHD flow in a channel filled with porous medium

An exact solution of an oscillatory MHD flow of a viscous, incompressible and electrically conducting fluid in an infinite horizontal channel is presented. The channel is filled with a porous medium and a magnetic field is applied perpendicular to the plates of the channel. During the analysis it is found that the mathematical formulation and the solution obtained of the problem by Makinde and Mhone (2005) are both wrong. Equations (2.1) to (2.4) do not govern the flow problem shown geometrically in their Fig.1. This important flow problem is again formulated mathematically in the present paper and a fresh and a correct closed form analytical solution is obtained. The validity and correctness of the present solution is verified by the limiting case for H=s=0. In this case of oscillatory flow in the absence of a magnetic field and through ordinary medium the solution reduces to the well known result obtained by Schlichting and Gersten (2001). The results are discussed in detail with the help of graphs for the variations of different flow parameters.