Modelling the effect of surface roughness on lubrication in all regimes

A model of lubrication in all regimes is presented. Two length scales are defined, cell and global length scale levels. Surface roughness effects are modelled on the local cell level, while the actual lubrication problem is solved on the global level. Surface roughness influences contact mechanics, when surfaces are boundary lubricated, as well as hydrodynamic film formation. The all-regimes lubrication model is applied to thrust bearings and wet clutches. The cell level model can be further improved to also include wear and better friction estimation.