New Treatment of Pressure Boundary Conditions for DSMC Method in Micro-Channel Flow Simulations

Abstract

Using DSMC to simulate micro flows in micro-channels, the numerical treatment of boundary conditions is very important. In this paper, several previous numerical treatments of boundary conditions are discussed with their merits and demerits, and a new treatment method based on the assumption of certain pressure distribution in the cells for boundary conditions is proposed. As comparable validity tests, it is applied in the DSMC simulations for the Poiseuille micro flows in micro-channels with four types of classical pressure boundary conditions. The dimensionless velocity profiles are shown and compared with analytical solutions derived from the Navier-Stokes equations with slip boundary conditions. The pressure distributions along the centerline of the micro-channel with the different boundary conditions are presented, and the simulation solutions agree well with the slip analytical solutions. As the Knudsen number increased, a strong linearity of the pressure distribution can be evidently predicted by the new method. Compared with the inlet and outlet velocity distribution, it is shown that the new method has better efficiency than the previous methods in the convergence.

A DSMC investigation of gas flows in micro-channels with bends

“…More recently, Ye et al [10,11,22] proposed boundaries similar to those of Nance et al [6] and Wang and Li [21], but they used different correction factors at the inlets and outlets in order to improve the heat transfer results in micro-channels whose surface temperature is substantially different from the gas inflow temperature.…”

“…There is plentiful DSMC data available for straight micro-channels [6][7][8][9][10][11]; contrastingly, there is a real absence of any data for microchannels with bends. Micro-channels in practical applications tend to have a large number of bends, so there is a clear need for DSMC data on what effect bends can have on a micro-channel flow in the slip and transition Knudsen number regimes.…”