(162ai) Predicting Diffusivity in Quenched-Annealed Systems

Transport of fluids in random porous media is central to a host of natural phenomena and technological applications; however, there are still many outstanding fundamental questions [1]. Progress in understanding some of these issues can be made by exploring an interesting class of models introduced by Madden and Glandt [2], so-called quenched-annelaed (QA) systems, which are readily amenable to theoretical and computational analysis. In this talk, we propose a simple equation for predicting the self-diffusivity of mobile particles in monodisperse QA systems that only requires knowledge of the diffusivity of the bulk, homogeneous fluid and the statistical geometry of the matrix particles. Comparison between predictions of this equation and the "exact" results obtained via molecular dynamics simulations shows a very good agreement over a wide range of fluid densities. The general applicability of this approach is demonstrated by analyzing diffusivity of mobile particles within different types of random matrices which qualitatively correspond to different physically realizable systems [3].

[1] S. Torquato, Random Heterogeneous Materials: Microstructure and Macroscopic Properties (Springer-Verlag, New York, 2002).

[2] W. G. Madden and E. D. Glandt, J. Stat. Phys. 51, 537 (1988).

[3] R. Chang, K. Jagannathan and A. Yethiraj, Phys. Rev. E 69, 051101 (2004).