用直接模拟Monte Carlo方法计算微通道的流动与换热

Prediction of Flow and Heat Transfer in Micro-Scale Channel with Direct Simulation Monte Carlo Method

应用直接模拟MonteCarlo(DSMC)方法模拟了平行板微通道中进口流速较低时的气体流动,应用质量守恒来处理进出口的压力边界.所模拟流动的Knudsen数的范围是0 05～1 00,涉及了滑移区、过渡区和自由区.计算了来流与平板等温以及平板对称加热两种工况,揭示了压缩性与稀薄性对所研究微平行板通道中流动与换热的影响.研究结果表明:①随着Knudsen数增大,沿程压力变化的非线性逐渐减弱,沿程速度变化与温度变化都趋于平缓,速度滑移量和温度跳跃量增大;②沿程温度变化在进出口处较为明显;③气体在微通道内的换热主要集中在进出口处,在通道中部换热很弱.

The gas flow with low inlet velocity in micro parallel plate channel was simulated with direct simulation Monte Carlo (DSMC) method. The inlet and outlet boundaries for pressure were dealt with mass conservation condition. The Knudsen number varies from 0.05 to 1.00 and covers the slip, transition, and free molecule regions. Two cases were considered, i.e., the inlet fluid and plates having the same temperature and the fluid heated by the plates symmetrically. The effects of rarefaction and compressibility on the flow and heat transfer characteristics are analyzed. The simulation results show that: (1) With the increase of Knudsen number, the non-linearity of pressure distribution deceases, and the stream-wise variation of both the velocity and temperature reduces; (2) The variations of temperature at the channel inlet and outlet are significant; (3) The heat transfer between the channel and the gas is mainly concentrated in the inlet and outlet regions while the heat transfer process is rather weak in the middle part of the channel.