Topographic effect of surface roughness on thin-film flow

This article addresses the effect of topographic structure of surface roughness on the flow of a thin film over a rotating disk. Six factors, namely centrifugation, surface tension, viscosity, air-shear, disjoining pressure, and surface roughness, that affect the depletion of the film are considered. Depletion histories of a thin film are given for cases involving deterministic as well as stochastic descriptions of surface roughness. It has been found that surface roughness of the disk plays a significant role in thin-film flow, and different topographic structures of the surface roughness lead to different asymptotic limits of liquid retention. The interplay of topographic parameters such as the height, skewness, and frequency of surface asperities on lubricant retention is also investigated.