Combined effects of surface roughness and couple stresses on squeeze film lubrication between porous circular stepped plates

In this paper, combined effects of surface roughness and couple stresses on squeeze film lubrication between porous circular stepped plates is analysed. In the context of Christensen stochastic theory for the study of surface roughness two types of one-dimensional surface roughness pattern, viz., azimuthal roughness pattern and radial roughness pattern are considered. The stochastic: modified Reynolds equation for these two types of roughness patterns is derived for the couple-stress fluid. The Beavers-Joseph slip boundary condition on the fluid-porous interface is utilized. Closed form expressions for the mean load carrying capacity and squeeze film time are obtained. It is found that the squeeze film characteristics are improved for the azimuthal surface roughness pattern. However, the performance of the squeeze film bearing suffers due to the presence of radial roughness pattern.