Transport properties in dense fluids and their binary mixtures

Abstract

Abstract A critical appraisal of the ability of the effective diameter hard-sphere theory (EDHST) for predicting thermal conductivities, and shear and bulk viscosities of fluids interacting through the Lennard-Jones potential is presented. This method relies on the use of the kinetic theory of hard-spheres and the state-dependent effective diameters given by the equilibrium liquid state theory. Predictions using this method are compared with molecular dynamics data given by several authors. In the dense regime this procedure, using a variational scheme to obtain the effective hard-sphere diameters makes predictions with an average global deviation of 37% for the shear viscosity, 32% for the bulk viscosity, and 10% for the thermal conductivity. However, in certain regions of the phase diagram the predictions are better. All other schemes give worse results than the variational scheme, except in the case of the shear viscosity in certain regions of the phase diagram (for this case we include the low density regions), where the Verlet and Weis scheme gives better results. For mixtures, we calculated the transport properties of mixtures using the equivalent one-fluid approximation, and comparisons with molecular dynamics calculations previously reported were performed. Our results are quite satisfactory. In addition, we made comparisons with actual fluids and extended our procedure to fluids of nonspherical molecules.