Determination of slip coefficient for rarefied gas flows using direct simulation Monte Carlo

A qualitative analysis is first carried out to determine the slip coefficient as a function of two dimensionless parameters. An intensive computation using the direct simulation Monte Carlo method is then carried out to simulate the Couette flows between two walls for different gas, number density, wall (plate) velocity (U_w), wall temperature (T_w) and distance between the two walls. Numerical results show that the slip coefficient is proportional to the mean free path _gw of molecules colliding with the wall, which is affected by the number density, the wall temperature and gas mass. The slip coefficient is finally found to be 1.125 _gw. This slip coefficient is verified for five gases, and validated under the conditions of U_w300 m s^-1 and T_w500 K. This slip coefficient is very useful for slip flow analysis in micro-electro-mechanical systems using N-S equations.