DSMC Analysis of Fluid Film Damping in Laterally Oscillating Microstructures

Abstract

Fluid film damping in laterally oscillating microstructures is investigated in the entire Knudsen regime and a wide range of Stokes numbers by using the unsteady DSMC method. DSMC results are validated through comparisons with theoretical predictions at continuum and free molecular flow regimes. Dynamic response of the flow, including the velocity profile, normalized velocity amplitude distribution, and phase angle are presented at various flow conditions. Based on the DSMC data, quality (Q) factors are computed to quantify the damping characteristics of the system. The quality factor increases with rarefaction, proportional to the Knudsen number. The Q-factors from DSMC are compared with predictions of slip-based continuum models. Although the DSMC-based Q-factors successfuly satisfy the theoretical criterion in the free molecular flow regime, slip-based continuum models fail to predict the Q-factors in the transition and free molecular flow limits. These models also fail for high Stokes number conditions.