Simulating the time-dependent diffusion coefficient in mixed-pore-size materials
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Zhang-2011-Simulating the time-dependent diffusion coefficient.pdf
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Author(s)
Zhang, Zhigang
Johnson, David L.
Schwartz, Lawrence M.
Date Issued
September 2011
Journal
Physical Review E
Publisher
American Physical Society
Citation
Zhang, Zhigang, David L. Johnson, and Lawrence M. Schwartz. “Simulating the Time-dependent Diffusion Coefficient in Mixed-pore-size Materials.” Physical Review E 84.3 (2011): [8 pages] Web.©2011 American Physical Society.
Version
Final published version
Abstract
Porous media with a wide distribution of pore sizes are quite common. We show that variable-step-size random walk simulations can be used to model the time-dependent diffusion coefficient D(t) in such porous media. The issue to be overcome is that, in variable-step-size walks, each walker carries its own “clock,” and its position is known only at a random set of times. Thus, a direct ensemble-average calculation of (delta r[superscript 2](t))(the mean-square distance traveled at time t) is problematic. We introduce a sequence of approximations that overcome this apparent difficulty. Calculations are carried out on periodic systems that contain pores of quite different sizes. Where possible, our results are compared to those obtained using fixed-step-size random walks.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1103/PhysRevE.84.031129
