In solving the Navier Stokes equation, the typical boundary condition imposed on the tangential velocity at a solid surface is that of no-slip. However, it is known that for gaseous flow there always exists a non-zero velocity near the wall, especially at relatively big Knudsen number. Is there any good book/paper that I can get such information? In particular, I am interested in the slip velocity of nitrogen gas at Kn=0.07~0.1. Thanks!