The interpretation of transport coefficients on the basis of the Van der Waals model

The Van der Waals model for transport properties which forms a very satisfactory basis for the interpretation of dense-gas transport-coefficient data, is applied to dilute gases to determine the effect of attractive forces between real molecules on the values of transport coefficients. It is found that experimental viscosity coefficient and thermal-conductivity coefficient data are lower than the values calculated by up to 40%. For the rare gases these differences are found to be related simply to the temperature and molar volume and expressions are given which reproduce the available experimental data generally to better than 2% over the whole density range.