Transport Coefficients of van der Waals Fluids and Fluid Mixtures

Abstract

We propose models which are direct extensions to dynamical domains of van Kampen's approach to van der Waals fluids, and are suited for studying transport phenomena near crit­ ical points. Models are described by hydrodynamic equation for hard sphere fluids where long· range interactions are added as semi-macroscopic forces acting among mass elements of the fluids, and are in principle capable of rigorous treatment of critical anomalies. Here we used the models to obtain the lowest order corrections of critical fluctuations to transport coefficients. Denoting the force range by 1 and the reduced temperature distance from the critical point by E, we found the following lowest order corrections: (a) for one-component fluids, shear viscosity 'l},,-,1-1IEI-i/2, bulk viscosity (,,-,1-1IEI-5/2, thermal conductivity A,l-1IEI-1I2, and (b) for binary solutions near critical solution points, diffusion constant D,l-1IEli/2, 'l}' constant+l-i IEli/2, (,l-1IEI-312, A,l-1IEI-i/2, and thermal diffusion constant DT,l-1IEI-1I2.