Ab initio simulation of rarefied gas flow through a thin orifice

• Flow rate and flowfield for rarefied gas flow through an orifice have been calculated.
• The DSMC method based on the ab initio potential was applied.
• The influence of the potential on the flow rate does not exceed 2%.

A rarefied gas flow through a thin orifice is calculated for the three noble gases, helium, argon and krypton, applying the direct simulation Monte Carlo method based on the ab initio potential. The calculations have been carried out over the whole range of the gas rarefaction and for several values of the pressure ratio with the numerical error less than 0.5%. A comparative analysis showed that the relative difference of the flow rate based on the ab initio potential from that obtained for the hard sphere molecular model depends on many factors, namely, gas species, pressure ratio, gas rarefaction and gas temperature. Among the gases considered here, the difference for helium is smallest and does not exceed 0.7%. The deviation for krypton is largest and reaches 1.4%. A relative deviation of the flow rate due to the temperature variation is within 0.9%. A comparison of the axial distributions of density, temperature and bulk velocity shows that the Mach discs for the ab initio potential are stronger than those for the hard sphere model.