Exact molecular dynamics and kinetic theory results for thermal transport coefficients of the Lennard-Jones argon fluid in a wide region of states.

Abstract

The self-diffusion, shear viscosity, bulk viscosity, and the thermal conductivity coefficients of the Lennard-Jones argon fluid were calculated by kinetic theory and molecular dynamics computations. Densities between 1.3 and 1.5 g ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and a temperature range of 100--300 K were considered for the comparison. The results indicate that the refined versions of the kinetic variational and reference theories give agreement with the exact data in a certain temperature region, except for the bulk viscosity, which is predicted much too high. Furthermore, the temperature dependence of the transport coefficients at constant density is correctly given solely for the self-diffusion and the thermal conductivity coefficients. In particular, the strong increase of the shear viscosity near the phase transition to the solid state is poorly reflected by the theory. On the other hand, among all the transport coefficients, the latter is theoretically well approximated for a relatively large temperature range, apart from the self-diffusion coefficient which represents, however, a purely kinetic quantity.