Prediction of transport properties of dense molecular fluids using the effective diameter hard sphere theory

Abstract

The present paper explores the ability of the effective diameter hard sphere theory to estimate the transport properties of a fluid made up of particles interacting through the Gaussian overlap model. This method relies on the assumption that at high densities the behaviour of a fluid is dominated by harsh repulsive forces. Hence, the properties of the fluid can be given in terms of a hard convex body fluid, and the properties of this fluid can also be expressed in terms of an effective hard sphere fluid. The state-dependent diameter of the reference hard sphere fluid is obtained through the blip function theory, well known in the equilibrium liquid theory of molecular fluids, in terms of the Gaussian overlap model parameters. Comparisons with measured thermal conductivities and shear viscosities for nitrogen and benzene were made, because of the lack of molecular dynamics data. Our results are in good agreement with experimental data over wide density ranges, and the sources of discrepancy could be explained by the fact that the Gaussian overlap model parameters used for those fluids are not accurately determined. Despite this, our results are surprisingly close to experimental determinations.