Comparison of wall models for the molecular dynamics simulation of microflows

Molecular dynamics Poiseuille flow simulations were conducted with diffuse, one-zone, two-zone, and three-zone wall models for tubes containing argon or nitrogen for tube radii from 20 to 65 at both sub- and supercritical temperatures. The diffuse wall showed some variation from the analytical velocity profile in the tube, whereas the explicitly modeled walls performed very well. All wall models were able to maintain system temperature to reach the desired simulation conditions. The diffuse wall failed to capture the nanoscale behavior of the flow. The explicitly modeled walls performed very well at the nanoscale but determining the appropriate fluid-wall interactions is critical.