Hydromagnetic rotating flow of a fourth-order fluid past a porous plate

The rotating flow in the presence of a magnetic field is a problem belonging to hydromagnetics and deserves to be more widely studied than it has been to date. In the non-linear regime the literature is scarce. We develop the governing equations for the unsteady hydromagnetic rotating flow of a fourth-order fluid past a porous plate. The steady flow is governed by a boundary value problem in which the order of differential equations is more than the number of available boundary conditions. It is shown that by augmenting the boundary conditions based on asymptotic structures at infinity it is possible to obtain numerical solutions of the nonlinear hydromagnetic equations. Effects of uniform suction or blowing past the porous plate, exerted magnetic field and rotation on the flow phenomena, especially on the boundary layer structure near the plate, are numerically analysed and discussed. The flow behaviours of the Newtonian fluid and second-, third- and fourth-order non-Newtonian fluids are compared for the special flow problem, respectively. Copyright (C) 2004 John Wiley Sons, Ltd.