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Knudsen diffusivities and properties of structures of unidirectional fibers
Author(s) -
Tomadakis Manolis M.,
Sotirchos Stratis V.
Publication year - 1991
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690370807
Subject(s) - knudsen number , perpendicular , fiber , porosity , monte carlo method , knudsen diffusion , radius , percolation (cognitive psychology) , diffusion , materials science , displacement (psychology) , composite material , mechanics , molecular physics , geometry , chemistry , physics , thermodynamics , mathematics , psychology , statistics , computer security , neuroscience , computer science , psychotherapist , biology
Effective Knudsen diffusion coefficients are presented for fibrous structures consisting of parallel, nonoverlapping or partially overlapping fibers. They are computed by means of a Monte Carlo simulation scheme which is employed to determine the mean square displacement of molecules travelling in the interior of the porous medium for large travel times. The results show that structures of paralle, non‐overlapping fibers have smaller effective diffusion coefficients parallel to the fibers than structures of parallel, randomly overlapping fibers of the same porosity and fiber radius, but larger in directions perpendicular to the fibers. Partially overlapping fiber structures are found to exhibit behavior intermediate to those of the two extreme cases. Molecular trajectory computations are also used to obtain results for the structural properties of partially overlapping fiber structures (e.g., porosity and internal surface area, accessible porosity and internal surface area, and percolation threshold), which are compared with some results of the literature for the equivalent problem of partially overlapping disks on a plane.