Transport properties of homonuclear diatomics

Abstract

The algorithm of Evans and Watts [1] is used to calculate shear viscosity, bulk viscosity and thermal conductivity of dilute gases modelled by diatomic Lennard-Jones potentials. The results are given in reduced form as a function of T* and R* (R* = 0·2, 0·3 and 0·5). They can be used to give the transport coefficients of any homonuclear diatomic modelled by a diatomic Lennard-Jones (12, 6) potential, provided that the mass and force centres are assumed to be coincident. In applying the results to nitrogen it is found that the effective pair potential of MacRury et al. [2] predicts dilute gas transport coefficients in agreement with experiment for the temperature range 200 to 600 K. It is shown that the three diatomic Lennard-Jones potential parameters for nitrogen can be determined by a joint fit of second virial and bulk viscosity data. The fitted value of R* is 0·285±0·03, showing that to this level of accuracy the diatomic Lennard-Jones pair and effective pair potentials for nitrogen are consistent.