Effect of Wall Roughness on the Slip of Fluid in a Microchannel

Abstract

The molecular dynamics simulation of fluid flow through a two-dimensional microchannel channel with atomically rough walls is reported. The roughening elements distributed on the surface of solid walls were modeled by atomic modules with specified amplitude and periodicity. The effect of various parameters such as wall energetic, amplitude, periodicity, and topology of roughening elements on the slip of fluid is investigated. The results indicate that the Knudsen number is not the sole parameter identifying the slip condition at the walls when the amplitude of surface roughness is comparable with the molecular mean free path. It was also found that the topology and number of roughening arrays can influence the slip of fluid at solid surface. The adsorption of wall does not show any significant effect on the slip in rough channel. However, it plays an important role on the amount of slip in smooth channel.