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Monte Carlo Simulations of Effective Diffusivities in Three—Dimensional Pore Structures

Published online by Cambridge University Press:  28 February 2011

Sebastian C. Reyes ,
Enrique Iglesia  and
Yee C. Chiew
Sebastian C. Reyes
Affiliation:
Corporate Research Laboratories, Exxon Research and Engineering Company, Annandale, NJ 088011
Enrique Iglesia
Affiliation:
Corporate Research Laboratories, Exxon Research and Engineering Company, Annandale, NJ 088011
Yee C. Chiew
Affiliation:
Department of Chemical and, Biochemical Engineering, Rutgers University, Piscataway, NJ 08855
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Abstract

A hybrid discrete/continuum Monte Carlo technique combining random walk simulations with first passage time (FPT) concepts is developed here in order to estimate diffusion properties of randomly-assembled sintered porous structures. This work combines the creation of realistic porous solid structures with controlled pore size, shape, and tortuosity features with the application of an efficient algorithm for calculating effective diffusivities in all diffusion regimes (Knudsen, transition, and molecular). The hybrid simulation technique consists of creating a “protective” boundary layer surrounding solid surfaces within which discrete random motion simulations are performed while continuum FPT results are used in the remaining pore space. The boundary layer thickness reflects a characteristic length scale, of the order of a few mean free paths, over which the FPT approximation breaks down. This procedure significantly reduces the computations required to cover statistically representative regions of the porous structure,a serious shortcoming in previous studies of gas diffusion through porous solids; it leads to effective diffusivity estimates that are in excellent agreement with experimental measurements.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 195: Symposium S – Physical Phenomena in Granular Materials , 1990 , 553
Copyright
Copyright © Materials Research Society 1990

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References

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