The Rayleigh Taylor stability in a finite thickness layer of a viscous fluid bounded below by a densely packed thick porous thick porous layer and above by a rigid surface has been studied subject to linear anal. using approxns. in effect similar to lubrication and Stokes approxns. The problem is studied anal. It is shown that the nature of the linear stability curve is controlled by the slip parameter α and the thickness of the fluid layer h, while its shape is controlled by the ratio of the surface tension to the normal stress
