The Viscosity of Compressed Gases

Abstract

New data and a new theory for the viscosity of compressed gases are presented. Data for nitrogen, hydrogen and a mixture of these gases are given, in the calculation of which, the "end effects" are not neglected as has been done in the past. Previous viscosity data are of doubtful validity owing to neglect of this factor. The theory is based on an analogy between the kinetic pressure and viscosity of a gas and is derived using an equation of state of the Lorentz type. Allowance is made for the difference between the viscosity and compressibility covolumes. The theory is substantiated experimentally and further confirmed by the recalculation of other data on the variation of Reynolds' criterion with the pressure, which is here shown to be constant. The mixture data offer a direct opportunity of comparing the Lorentz and linear rules for the calculation of the covolume of a mixture from the covolumes of the components and such comparison indicates that the Lorentz rule is not to be preferred. The substantiation of the new theory is the first direct proof of the validity of the separate treatment of the kinetic and cohesive pressures in the equation of state.