TRANSPORT-PROPERTIES OF THE HARD ELLIPSOID FLUID

Transport properties of isotropic fluids composed of hard ellipsoids of revolution are studied using molecular dynamics simulation. The self-diffusion coefficient, the shear viscosity, and the thermal conductivity are evaluated for a range of densities and elongations and are compared with the results from an Enskog kinetic theory for nonspherical bodies. The full anisotropic pair correlation function, which is required input in an Enskog kinetic theory, can be obtained from simulation or can be approximated. If the pair correlation function is taken as isotropic on the contact surface, with a contact value derived from an accurate equation of state, the resulting kinetic theory transport properties agree to within a few percent of those calculated on the basis of the exact pair correlation function. The simulation and the kinetic theory values for the shear viscosity and the thermal conductivity show the same qualitative behavior, i.e., increasing with density and with particle nonsphericity. Quantitatively, there is good agreement at low densities (up to 30% of closest packing); at higher densities (60% of closest packing), deviations from Enskog theory are larger than and in the opposite direction to those seen for hard spheres. The Stokes-Einstein and Debye relations are tested and indicate a transition rom a kinetic theory region towards the hydrodynamic limit as density increases.