Knudsen pumps modeling with Lennard-Jones and ab initio intermolecular potentials

•Viscosities for He, Ar and their mixture with different potentials were calculated.•2D and 3D rarefied flows of gas mixture in Knudsen pump were modeled.•The non-monotonic behavior in time of pumping and gas separation was detected.

The paper presents some results of computing of a gas mixture flows in Knudsen pumps. The simulations are carried out by numerically solving the Boltzmann kinetic equation by the conservative projection method. Interactions of gas molecule are modeled by Lennard-Jones and the newest ab initio potentials. The values of the pumping rate, gas mixture separation, and the graphics of gas flow parameters inside the pumps are given. The results obtained with different molecular models are compared and the influence of the molecular potentials on macroscopic flow parameters is shown. The simulations are performed in plane and 3D geometries.