Influence of non-Newtonian fluids on the performance of a soft elastohydrodynamic lubrication contact with surface roughness

The paper focuses on the development and results of a numerical model to evaluate the fluid transfer behaviour for non-Newtonian fluids in a rough soft elastohydrodynamic nip contact. The solution required coupling of the fluid and elastomer regimes, with a multi-gridding technique to facilitate the high mesh densities required to capture the rough surface representation. The non-Newtonian fluid behaviour was modelled using a power-law model. The study evaluated circumferential and longitudinal roughness forms. The introduction of longitudinal roughness introduced significant shear in the nip with the resultant large change to the viscosity profile. This also removed the stagnation point in the centre of the nip. The longitudinal roughness had a large impact on the film thickness and flow through the nip while the circumferential affected the local performance of the nip but not its overall pumping capacity.