Development of a Momentum Exchange Coefficient Model for Continuum to Rarefied Planar Laminar Gas Flows

Gaseous flow in micro-scale systems comprised of moving components experience Fluid-Structure Interaction (FSI) and rarefaction when the length scales are small. While many commercial codes claim the ability to simulate FSI problems, such a combination is very challenging to model. Here we propose a momentum exchange coefficient model within the FSI algorithm, MPM-ICE, that enables the simulation of rarefied flow. The proposed model was derived using the Maxwell first-order velocity slip boundary condition. The model is verified using analytical solutions for pressure-driven Poiseuille and Couette planar flow. In addition, the model is validated using experimental pressure data of microchannel gas flow and DSMC simulation results. Unlike the previous model, the proposed model is more robust and is nearly insensitive to the grid size and the solid particle distribution around the surface. In addition, the model is universal since it is applicable for flow in the continuum and slip regimes.