Molecular dynamics simulation on rarefied gas flow in different nanochannel geometries

A three dimensional Molecular Dynamics simulation method was used to study the effect of different geometries for rarefied gas flows in nanochannels. Argon molecules have been used. The velocity profiles in the channel were obtained and analyzed with three different channel geometries: a circular, a rectangular (square), and a slit channel. We found that when using the same driving force, the maximum velocity of the flow increases when the geometry changes in the order from circular geometry to rectangular geometry to slit geometry, where the latter becomes 2∼2.5 times as large compared with either the rectangular or circular channel. Rectangular channels showed a similar maximum and slip velocity as the circular channel while the velocity profile was qualitatively similar to the slit channel for Kn higher than 1.0. We also investigated the effect of different Knudsen numbers on the velocity profiles. A channel width of 50nm is used for the simulation. We found that for Kn higher than 2∼3, the Knudsen number has a comparably small influence on the slip velocity for circular channel and rectangular channel.