Kinetic modeling of temperature driven flows in short microchannels

The temperature driven gas flows in both a two-dimensional finite length microchannel and a cylindrical tube have been studied numerically, with a goal of investigating performance optimization for a nanomembrane-based Knudsen Compressor. The numerical solutions were obtained using the direct simulation Monte Carlo (DSMC) method and a discrete ordinate method for the ellipsoidal statistical and Bhatnagar–Gross–Krook models. The Knudsen number was 0.2 and the length-to-height ratio 5. Three different wall temperature distributions were considered: linear, step-wise, and a non-monotonic profile typical for a radiantly heated Knudsen Compressor's membrane. The short channel end effects are characterized, and the sensitivity of the mass flow to a non-monotonic temperature distribution is shown.