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

In this paper, a theoretical study on the effects of MHD and surface roughness on the couple stresses squeeze film lubrication between circular stepped plates is presented. The modified averaged Reynolds equation is derived on the basis of Christensen's stochastic theory for rough surfaces. The closed form expressions are obtained for the mean squeeze film pressure, load carrying capacity and squeeze film time. The results are presented for different operating parameters. It is observed that the effect of applied magnetic field on the squeeze film lubrication between circular stepped plates with couple stress fluids is to increase the load carrying capacity significantly and to delay the time of approach as compared to the corresponding non-magnetic case.

► The effect of magnetic field is to increase the mean load carrying capacity.
► The effect of magnetic field is to lengthen the mean squeeze time.
► The relative, load RW and squeeze film time RT⁎RT⁎ are found to be functions of C, K, M0 and l.
► The azimuthal/radial roughness pattern increases/decreases the load carrying capacity.
► The azimuthal/radial roughness pattern increases/decreases the squeeze film time.