The Mathematical Institute, University of Oxford, Eprints Archive

Diffusion of multiple species with excluded-volume effects

Bruna, M. and Chapman, S. J. (2012) Diffusion of multiple species with excluded-volume effects. Journal of Chemical Physics . (Submitted)



Stochastic models of diffusion with excluded-volume effects are used to model many biological and physical systems at a discrete level. The average properties of the population may be described by a continuum model based on partial differential equations. In this paper we consider multiple interacting subpopulations/species and study how the inter- species competition emerges at the population level. Each individual is described as a finite-size hard core interacting particle undergoing Brownian motion. The link between the discrete stochastic equations of motion and the continuum model is considered systematically using the method of matched asymptotic expansions. The system for two species leads to a nonlinear cross-diffusion system for each subpopulation, which captures the enhancement of the effective diffusion rate due to excluded-volume interactions between particles of the same species, and the diminishment due to particles of the other species. This model can explain two alternative notions of the diffusion coefficient that are often confounded, namely collective diffusion and self-diffusion. Simulations of the discrete system show good agreement with the analytic results.

Item Type:Article
Subjects:D - G > General
Research Groups:Oxford Centre for Collaborative Applied Mathematics
ID Code:1645
Deposited By: Peter Hudston
Deposited On:05 Jan 2013 10:23
Last Modified:29 May 2015 19:20

Repository Staff Only: item control page