NUMERICAL SIMULATION OF GAS FLOW AND MIXING IN A MICROCHANNEL USING THE DIRECT SIMULATION MONTE CARLO METHOD

The direct simulation Monte Carlo (DSMC) method was employed to investigate gas flow and mixing in a microchannel at near-atmospheric pressure conditions. Simulations for pressure-driven flows were first carried out for a single-component gas flow in a microchannel. Mixing of two parallel gas streams (H 2 and O 2 ), separated by a splitter plate and then entering a microchannel, was considered. The effects of the inlet velocities, the inlet-outlet pressure difference, and the pressure ratio of the incoming streams (H 2 and O 2 ) on the mixing behavior were considered. The effect of the "accommodation coefficient" of the solid wall of the microchannel on the mixing behavior was also 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 inlet pressures, mixing is found to decrease with the increase of the pressure ratio. The mixing process is found to be much slower for nearly specularly reflected walls compared to the mixing in a microchannel with completely diffuse walls.