Diffusion of Colloidal Fluids in Random Porous Media

TL;DR

This paper uses the SCGLE theory to model how colloidal fluids diffuse in porous media, showing that with proper static structure input, it accurately predicts the fluid's dynamic behavior.

Contribution

It applies the SCGLE theory to porous media, demonstrating its effectiveness in predicting colloidal fluid dynamics with static structure inputs.

Findings

SCGLE theory accurately predicts colloidal fluid dynamics in porous media

Proper static structure factors are crucial for correct predictions

The model simplifies the porous medium as fixed spherical particles

Abstract

A simple manner to describe the diffusive relaxation of a colloidal fluid adsorbed in a porous medium is to model the porous medium as a set of spherical particles fixed in space at random positions with prescribed statistical structural properties. Within this model one may describe the relaxation of concentration fluctuations of the adsorbed fluid by simply setting to zero the short-time mobility of one species (the porous matrix) in a theory of the dynamics of equilibrium colloidal mixtures, or by extending such dynamic theory to explicitly consider the porous matrix as a random external field. Here we consider the first approach and employ the self-consistent generalized Langevin equation (SCGLE) theory of the dynamics of equilibrium colloidal mixtures, to describe the dynamics of the mobile component. We conclude that if the correct static structure factors are provided as input, the SCGLE theory correctly predicts the main features of the dynamics of the permeating fluid.