Combination Rules for Binary Gaseous Mixtures Deduced from Viscosity

Abstract

In this paper, the results are reported of two separate tests on the validity of three mixing rules that are commonly employed in determining the force parameters for unlike molecular collisions from those for like‐molecular collisions where the interaction may be described by means of a two‐parameterforcepotential. Both tests utilize the equations for the viscosity of dilute gases based on the Chapman–Enskog solution to the Boltzmann equation, together with highly precise experimental data on the viscosity of pure gases and binary gas mixtures. Both tests indicated that the experimental data are incompatible with the simple combination rules; that is, the arithmetic average for the distance parameter and the geometric mean for the energy parameter. The results of the second test show that the combination rule $${\epsilon }_{\mathrm{ij}}{\sigma }_{\mathrm{ij}}^6{\mathrm{\hspace{0.17em}=\hspace{0.17em}(\epsilon }}_{\mathrm{ii}}{\sigma }_{\mathrm{ii}}^6{\epsilon }_{\mathrm{jj}}{\sigma }_{\mathrm{jj}}^6{)}^{\text{1\hspace{0.17em}/\hspace{0.17em}2}}$$ is not contradicted by the experimental data. All possible binary combinations of the gases He, Ne, Ar, N₂, and CO₂ were analyzed for this report.