Computation of slip flow in microchannels using Langmuir slip condition

Abstract

To analyze microscale slip flows, a new simulation method is proposed that combines the Navier-Stokes solution with a new slip model called the Langmuir slip condition. The proposed method is applied to a gaseous microchannel flow model. The Langmuir slip model can simulate the velocity slip effect at the wall that comes from rarefaction and the compressibility effect of the microscale gases. The Langmuir slip model solution is analogous to the results of the well-known Maxwell slip condition. As the Knudsen number becomes higher, the Maxwell slip condition decreases pressure nonlinearity, while the Langmuir slip condition increases it slightly. Increased nonlinearity is more compatible with experimental results. The Langmuir slip condition does not require a cumbersome process in either calculation of streamwise velocity gradient at the wall or calibration of empirical accommodation coefficient. The proposed method using the Langmuir slip condition is proved to be an efficient, practical, and accurate tool in predicting microscale slip flow.