Remarks on the Stefan-Maxwell equations for diffusion in a dusty gas

Abstract

In the dusty-gas model for diffusion and flow of gases in porous media, diffusive fluxes are evaluated from Stefan–Maxwell equations for diffusion, and viscous fluxes then added on. It is shown that such augmented Stefan–Maxwell equations (augmented by terms for viscous flow) can be rearranged to give unaugmented Stefan–Maxwell equations (with modified values for diffusion coefficients). The alternative form gives a smooth interpolation between a Chapman–Enskog Lorentzian or quasi-Lorentzian diffusion coefficient and an Einstein Brownian diffusion coefficient for the diffusion of particles of an aerosol.