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The bulk and shear viscosity expressions for a binary mixture of hard spheres in the Enskog transport theory are generalized to the case in which one of the species (the solute) becomes polydisperse. The effect of polydispersity is expressed in terms of correction factors to results for a binary mixture with a monodisperse solute. These correction factors are evaluated for both a log-normal size distribution of solute particles with the solute mass-size relation of power-law form and a log-normal mass distribution of solute particles with fixed solute-particle size. The results reported here can be easily generalized to a multicomponent mixture involving several polydisperse species and several monodisperse species. [ABSTRACT FROM AUTHOR]

The shear viscosity expressions for a polydisperse hard-sphere fluid in both the dilute and dense fluid regions have been obtained as the solution of a set of linear integral equations in the Enskog transport theory. In the monodisperse limit we recover the known Enskog result. Explicit analytical solutions have been obtained for the special case of equal-mass particles. For general mass-size distributions, a simple numerical method has been proposed. Computations have been performed for a mass-size relation of power-law form. The two size distributions we have looked at are the Schulz distribution and the log-normal distribution. It is found that both distributions show similar effects on the shear viscosity. In the dilute-gas region, for each given fractal dimension, there exists a critical variance of the size distribution at which the shear viscosity attains a maximum. In the dense-gas region, the shear viscosity increases as the variance and the density increase except for the low density and the high fractal-dimension region where the shear viscosity attains a minimum at some particular variance. The shear viscosity diverges at a close-packing density that decreases with increasing variance. [ABSTRACT FROM AUTHOR]

The percolation behavior of simple fluids, modeled by a pair potential with a hard core and Yukawa tail, is studied by solving the connectedness Ornstein–Zernike equation analytically in the mean-spherical approximation for two different connectedness models. The simplest connectedness model is defined by a ‘‘connectedness shell’’ concentric to the sphere that defines the hard core. The analytical solution applies to the case of the shell width less than the hard-core diameter, which is the case for most applications of physical interest. The percolation loci on the phase diagram have been determined along with the average coordination number, which is found to be essentially constant along each locus, but different for different loci. A second model is introduced in which direct connectedness-in-probability is defined and applied to the gelation problem. This model can be thought of as a continuum generalization of the lattice model of gelation introduced by Coniglio, Stanley, and Klein. In the mean-spherical approximation, the models have percolation exponents (β=1/2, δ=5, γ=2, η=0, fractal dimensionality=2.5) that for the most part are quite close to the best available estimates of these exponents. [ABSTRACT FROM AUTHOR]

A kinetic theory for a fluid of particles interacting via a pair potential with hard-core plus truncated tail is described and used to derive a transport theory for the Lennard-Jones fluid as well as the square-well fluid. Numerical results for shear viscosity, thermal conductivity, and the self-diffusion coefficient are given for the Lennard-Jones fluid and compared with simulation and experimental results. Our Lennard-Jones theory proves quantitatively useful over a wide range of states. [ABSTRACT FROM AUTHOR]