Gas flow through an elliptical tube over the whole range of the gas rarefaction

A rarefied gas flow trough a long tube with an elliptical cross section is studied on the basis of the BGK kinetic model equation in the whole range of the Knudsen number varying from the free molecular regime to the hydrodynamic one. A wide range of the aspect ratio is considered. The mass flow rate is calculated as a function of the pressures on the tube ends.