Collisionally Uncoupled Model for the Contribution of Orientational Polarizations to Transport Properties of Dilute Gases. II. The Shear Viscosity

Abstract

The collisionally uncoupled model formulated in Paper I is applied to the calculation of the shear viscosity. The expressions obtained for the internal state contribution to the viscosity coefficients involve a summation, or integration, over the internal state frequency spectrum for each energy shell. The theory is first developed in a general way, and then a number of particular cases are considered. The expressions simplify in the commonly studied case of low magnetic fields, that is in the linear Zeemann region (and, equally, in the case of a linear Stark effect), because the frequency spectrum for each multiplet is then merely the Larmor frequency and its harmonics. As an example of this case, it is shown that the model gives a satisfactory one‐parameter description of the transverse viscosity coefficients of oxygen gas in the low pressure limit. The multiplet dependence of orientational relaxation times appears to be an important factor. The systematic choice of symmetry adapted phenomenological coefficients is also discussed, in particular the choice of symmetry adapted viscosity coefficients.