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J Environ Eng (New York)

Title:		Buoyant Advection of Gases in Unsaturated Soil
Author(s):		Seely GE; Falta RW; Hunt JR;
Address:		"Instructor, Dept. of Civ. Engrg., U.S. Air Force Academy, Colorado Springs, CO 80840"
Journal Title:		J Environ Eng (New York)
Year:		1994
Volume:		120
Issue:		5
Page Number:		1230 - 1247
DOI:		10.1061/(ASCE)0733-9372(1994)120:5(1230)
ISSN/ISBN:		0733-9372 (Print) 1943-7870 (Electronic) 0733-9372 (Linking)
Abstract:		"In unsaturated soil, methane and volatile organic compounds can significantly alter the density of soil gas and induce buoyant gas flow. A series of laboratory experiments was conducted in a two-dimensional, homogeneous sand pack with gas permeabilities ranging from 110 to 3,000 darcy. Pure methane gas was injected horizontally into the sand and steady-state methane profiles were measured. Experimental results are in close agreement with a numerical model that represents the advective and diffusive components of methane transport. Comparison of simulations with and without gravitational acceleration permits identification of conditions where buoyancy dominates methane transport. Significant buoyant flow requires a Rayleigh number greater than 10 and an injected gas velocity sufficient to overcome dilution by molecular diffusion near the source. These criteria allow the extension of laboratory results to idealized field conditions for methane as well as denser-than-air vapors produced by volatilizing nonaqueous phase liquids trapped in unsaturated soil"
Keywords:
Notes:		"PubMed-not-MEDLINESeely, Gregory E Falta, Ronald W Hunt, James R eng P42 ES004705/ES/NIEHS NIH HHS/ P42 ES004705-180026/ES/NIEHS NIH HHS/ 1994/09/01 J Environ Eng (New York). 1994 Sep 1; 120(5):1230-1247. doi: 10.1061/(ASCE)0733-9372(1994)120:5(1230)"