Effects of circumferential and radial rough surfaces in a non-Newtonian magnetic fluid lubricated squeeze film

The effects of surface roughness in circular squeeze film disks lubricated with a non-Newtonian magnetic fluid are investigated in this paper. Employing the stochastic model together with the microcontinuum theory and the ferromagnetic flow model, a non-Newtonian magnetic-fluid lubricated Reynolds equation including the influences of rough surfaces is derived, and applied to predict the squeeze film performances. According to the results, the surface roughness effects of circumferential structures increase the mean load capacity and lengthen the mean approaching time as compared to those of the smooth disks with a non-Newtonian magnetic fluid. However, the radial roughness patterns yield a reversed trend. In addition, the effects of rough surfaces on the squeeze film characteristics are more pronounced for circular disks operating with larger values of the surface roughness parameter, the non-Newtonian couple stress parameter, the volume concentration parameter and the magnetic Langevin parameter.