Recalculation of the friction constant and transport coefficients of liquid argon from the Rice-Allnatt theory

Abstract

The linear trajectory approximation of the ?soft? friction constant in the Rice-Allnatt theory of transport has been computed with specific attention to the lower limit of the integral. The results are significantly different from the Palyvos-Davis values for ζ^S in the dense gas region but agree within 2% in the liquid region. The Rice- Allnatt expressions for the coefficients of shear viscosity and thermal conductivity have been simplified and a correction of a numerical error in the collisional contributions to momentum and heat transfer is made. The coefficients D, η, and λ have been calculated for the corrected ζ^S and related expressions. No significant change in D is obtained, but a worsening of agreement with experimental viscosities and thermal conductivities occurs. Conversely, a better prediction of the ratio mλ/kη is obtained. More recent viscosity data for liquid argon indicate the theory is less satisfactory than has previously been considered. These results suggest that any improvement of this class of theory can only come through the use of a better representation of the radial distribution function.