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Laboratory Permeability Errors from Annular Wall Flow
Author(s) -
Tokunaga Tetsu K.
Publication year - 1988
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/sssaj1988.03615995005200010004x
Subject(s) - permeameter , annulus (botany) , hydraulic conductivity , permeability (electromagnetism) , porous medium , geology , mechanics , materials science , porosity , geotechnical engineering , soil science , chemistry , composite material , physics , soil water , biochemistry , membrane
Laboratory saturated hydraulic conductivity measurement errors introduced by permeameter fluid flow within gaps between sample cores and permeameter walls are estimated through a simple model that idealizes gap flow as occurring within a smooth annulus. The inner annulus boundary fluid velocity is matched to the Darcy velocity within the sample core. The ratio of flow within the annulus to that within the core, Q Rap / Q core , is shown to have both cubic and linear dependence on the gap width. Q Rap / Q core is also shown to be inversely dependent on both the core permeability and the permeameter radius. Although the model is very idealized, the strong possibility of overestimating permeabilities in laboratory cores is demonstrated. Related concerns include flow in fractured porous media, and potential errors in interpreting solute travel times in laboratory columns and field lysimeters.