Application of a parallel DSMC technique to predict flow characteristics in microfluidic filters

Using a parallel implementation of the direct simulation Monte Carlo (DSMC) method, periodic MEMS microfilters are studied in detail. The dependence of the flow characteristics on geometry, Knudsen number, pressure difference, spacing between the filter elements, and accommodation coefficients are investigated. By comparing DSMC results with the widely used analytical formulas, the validity range of the analytical approaches is evaluated. The simulation results show that velocity slip exists both on the filter channel walls and on the filter membrane and results in an increased flow rate. Velocity slip increases strongly with decreasing accommodation coefficients. For long channels, this results in a strong increase in flow rate; whereas for short channels, the increase in flow rate is limited. For the filter separations considered in this paper, we observe that separation between filter channels does not influence the flow rate within each channel.