Investigation of pressure-driven gas flows in nanoscale channels using molecular dynamics simulation

Pressure-driven gas flows in nanoscale channels are investigated in the present study using a molecular dynamics method. A reflecting particle membrane is used to produce the pressure difference between the inlet and outlet. The ratio of pressure difference to the average pressure along the channel is studied in detail, which is independent of the Knudsen number and temperature, but increases with the membrane's reflecting probability and channel aspect ratio. A scaling law for the pressure ratio is obtained from the simulation results, to determine the membrane's reflecting probability in molecular dynamics simulation, so the required pressure difference over a given channel can be produced. A case study of backward-facing step flow is then conducted, which demonstrates the necessity of using the pressure-driven method in non-uniform cross-sectional flow.