Enskog theory for multicomponent mixtures. II. Mutual diffusion

Journal Article · Tue Nov 01 04:00:00 EST 1983 · J. Chem. Phys.; (United States)

OSTI ID:5636382

Kincaid, J M; Lopez de Haro, M; Cohen, E G.D.

We present a detailed description of the mutual diffusion coefficients of binary and ternary dense fluid mixtures of hard spheres, as given by the revised Enskog theory (RET) of van Beijeren and Ernst and the standard Enskog theory (SET) of Tham and Gubbins. The formulas for the diffusion coefficients (see part I of this series, J. Chem. Phys. 78, 2746 (1983)) involve the contact values of the equilibrium pair distribution functions and the chemical potentials, for which the Carnahan--Starling approximation is used. The formulas, which were obtained by making an expansion in Sonine polynomials, are evaluated up to the third order and the convergence of the Sonine polynomial expansion is discussed. Except at low densities, the SET cannot be used to describe diffusion in hard-sphere mixtures. We find, using the CS approximation, that the SET gives values for the direct mutual diffusion coefficients that become negative at very high densities. A study is made of the dependence of the RET mutual diffusion coefficients on a variety of the parameters that determine the mixture (density, composition, molecular masses, and diameters) and a summary of the trends found is given. In particular, the influence of the addition of a third component on the mutual diffusion of two other components is discussed.

• Research Organization: Thermophysics Division, National Bureau of Standards, Washington, DC 20234
• OSTI ID: 5636382
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 79:9; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640410* -- Fluid Physics-- General Fluid Dynamics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BINARY MIXTURES
CHAPMAN-ENSKOG THEORY
DIFFUSION
DISPERSIONS
DISTRIBUTION FUNCTIONS
EQUATIONS
FLUIDS
FUNCTIONS
HARD-SPHERE MODEL
KINETIC EQUATIONS
MIXTURES
TRANSPORT THEORY