Testing the Mason—Monchick approximation for transport properties of pure diatomic gases

Abstract

Using the Mason—Monchick approximation, values for the diffusion and viscosity cross sections, their scaled ratio, A * and the diffusion coefficient for rotational energy are compared to full classical trajectory calculations at temperatures between 100 and 1000 K for N 2-N 2 collisions using the recent potential energy surface of van der Avoird. The errors in the approximate results generally decrease with increasing temperature, with the viscosity cross section more accurately described, 1.3% error at 1000 K, than the diffusion cross section, 4% error at 1000 K. The Mason—Monchick values for the diffusion coefficient are a better approximation to the diffusion coefficient for rotational energy than to the mass-diffusion coefficient.