Flow behaviours and boundary slip of nitrogen-oxygen mixture confined in nanochannel

Abstract

Molecular dynamics simulations have been carried out to study the Couette flow of nitrogen-oxygen mixture confined in parallel-plate nanochannels. The simulation results show that the shear stress linearly increases with the increase of the shear rate when the channel width is a constant, implying that the shear viscosity of the gas flow is constant in our simulations, which increases with the channel width. However, as the channel width reaches a threshold, the effect of channel width on fluid viscosity decreases gradually. The slip velocity decreases with increasing the solid-gas coupling strength and the number density of the gas molecules. Interestingly, the shear viscosity of fluid confined in the nanochannels increases with enlarging the component ratio of nitrogen. The particular issue at nanoscale is that the solid-like structure is extremely easy to form at the gas flow boundaries for the nitrogen molecules confined in the parallel-plate nanochannels.