Using lattice-Boltzmann simulation of steady-state gas flow we show that apparent
permeability values of nano-scale capillaries could be significantly higher than those
predicted by the Klinkenberg slip theory. The difference is due to kinetic effects of gas
molecules that have gone through inelastic collisions with the walls on those molecules that
make up the bulk fluid in the capillary. The kinetic energy that the bouncing back molecules
have and the associated momentum carried to the bulk fluid is not a trivial matter in …