Prediction of mixing of two parallel gas streams in a microchannel using the direct simulation Monte Carlo method

Abstract

Most micro-structure-related gas flows are usually in the slip and transitional flow regimes. Such flows are characterized by non-continuum behavior. For numerical analysis, the direct simulation Monte Carlo (DSMC) method offers a well established method to investigate such gas flows at high Knudsen number (Kn). In this paper, the DSMC method was employed to explore mixing flows in microchannels. Mixing of two parallel gas streams (H2 and O2) was considered within a microchannel. The effects of inlet velocity, the inlet-outlet pressure difference and the pressure ratio of the incoming streams (PH2,inlet/PO2,inlet) on mixing length were examined. The simulation results indicate that mixing decreases with the increase of inlet-outlet pressure difference. When the two streams enter the microchannel with different pressures, the mixing is also found to decrease with the increase of the pressure ratio. When the inlet and outlet pressures are held fixed along with O2 inlet velocity, higher inlet H2 velocity is also found to inhibit mixing.