Microchannel flow has attracted much attention due to the advent of
micro-electro-mechanical systems (MEMS). In this work, the direct
simulation Monte Carlo (DSMC) method is employed to study nitrogen gas
flows in a two-dimensional microchannel for different degrees of rarefaction. Meanwhile, in order to demonstrate the rarefaction effect on the flow characteristics of the microchannel flow, Gas-Kinetic Bhatnagar-Gross-Krook (Gas-BGK) scheme is performed for solving Navier-Stokes equations with slip velocity boundary condition imposed at the channel wall. It is found that the discrepancies in the flow characteristics
between the results obtained by the DSMC method and Gas-BGK scheme
will increase when the Knudsen (Kn) number of the flow field is increased.
For the flow characteristics around the wall, the rarefaction effect imposes stronger effect on the velocity field as compared to the temperature filed.The DSMC method should be employed in the flow analysis of MEMS as the Kn number of the gas flow is greater than 0.01.