A non-isothermal model for squeeze film damping of rarefied gas

This paper presents a compact model for thermal-squeeze film damping in the free-molecule regime. When a moving plate squeezes the gas, the plate does work on the gas, which causes a temperature rise in the gas. The thermal effect is usually neglected in the squeeze film damping, which is reasonable in the atmospheric environment because MEMS structures serve as heat sinks. However, MEMS structures are adiabatic in the free molecule regime. The thermal effect induces extra damping. Squeeze film damping is determined by both the gas flow and thermal effect, which should be called as thermal-squeeze film damping. The equations of mass and energy conservation are employed to model the gas flow and thermal effects, respectively. The model is compared with previously published experiments and models. According to the model, the degrees of freedom of gas molecules and surface roughness also play roles in thermal-squeeze film damping in the free-molecule regime, and are discussed qualitatively in the paper.