Effect of shape of molecules on transport and equilibrium properties of nonpolar polyatomic gases

Abstract

Collision integrals for nonpolar polyatomic gases have been evaluated on the assumption of fixed relative orientation per collision, with a 12-12-6 potential model, for a range of reduced temperatures and shape parameters. The effect of shape of molecules on diffusion and viscosity is small but not negligible. Thermal diffusion factors are most strongly affected; the presence of interaction due to nonsphericity in the shape of molecules can wipe out the thermal-diffusion inversion temperatures. The parameters of the spherical component of the potential have been obtained from the viscosity data for nine gases. These parameters have been used in conjunction with the second viral coefficient data to determine the quadrupole moments and shape parameters of the molecules. The quadrupole moments and shape parameters obtained are very reasonable.