DSMC Simulations of Squeeze Film Between a Micro Beam Undergoing Large Amplitude Oscillations and a Substrate

Abstract

This paper investigates the behavior of a gas film in a micro RF switch. A Two-dimensional numerical study of the flow field is performed as the micro-beam oscillates harmonically between its equilibrium position and the fixed substrate underneath. Unlike previous work in literature, the beam undergoes large displacements throughout the film gap thickness and the behavior of the gas film along with its impact on the moving RF switch (force exerted by gas on the beam’s front and back faces) are discussed. Since the gas film thickness is of the order of few microns (i.e. 0.01<Kn<1), the rarefied gas exists in the non-continuum regime and, as such, the Direct Simulation Monte Carlo (DSMC) method is used to simulate the fluid behavior. The impact of the squeeze film on the beam is investigated over a range of frequencies, velocity amplitudes, and for different film gases, corresponding to ranges of dimensionless flow parameters such as the Reynolds (Re), Strouhal (St) and Mach (Ma) numbers on the gas film behavior.