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Coupling Phenomena in Saturated Homo‐ionic Montmorillonite: IV. The Dispersion Coefficient
Author(s) -
Groenevelt P. H.,
Elrick D. E.,
Laryea K. B.
Publication year - 1980
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1980.03615995004400060007x
Subject(s) - dispersion (optics) , diffusion , flux (metallurgy) , molecular diffusion , convection , thermodynamics , chemistry , mechanics , materials science , physics , optics , metric (unit) , operations management , organic chemistry , economics
The movement of NaCl through the clay paste examined in this series of articles is analyzed in terms of dispersion and convection. The dispersion coefficient is proven to be velocity independent, i.e. the “hydrodynamic/lateral diffusion” part of the dispersion coefficient is negligible in comparison to the “molecular‐diffusion” part. Subsequently the thermodynamic equations for the salt flux and the liquid flux are reformulated for the condition of zero electric current. The salt flux equation is then further transformed in order to conform with the transport equation for the salt commonly used in dispersion studies, such that one recognizes a dispersion term and a convection term. The dispersion coefficient appears to contain an element due to salt sieving. The convection term appears as the product of the volume flux, the equilibrium salt concentration and a term involving the reflection coefficient.