title: An analysis of a mixed convection associated with thermal heating in contaminated porous media.
abstract: The occurrence of subsurface buoyant flow during thermal remediation was investigated using a two dimensional electro-thermal model (ETM). The model incorporated electrical current flow associated with electrical resistance heating, energy and mass transport, and density dependent water flow. The model was used to examine the effects of heating on sixteen subsurface scenarios with different applied groundwater fluxes and soil permeabilities. The results were analyzed in terms of the ratio of Rayleigh to thermal Peclet numbers (the buoyancy ratio). It was found that when the buoyancy number was greater than unity and the soil permeability greater than 10(-12) m(2), buoyant flow and contaminant transport were significant. The effects of low permeability layers and electrode placement on heat and mass transport were also investigated. Heating under a clay layer led to flow stagnation zones resulting in the accumulation of contaminant mass and transport into the low permeability layer. The results of this study can be used to develop dimensionless number-based guidelines for site management during subsurface thermal activities.
authors.affiliation: University of Toronto, Department of Civil Engineering, Toronto, ON M5S 1A4, Canada; York University, Department of Civil Engineering, Toronto, ON M3J 1P3, Canada. Electronic address: magdalena.krol@lassonde.yorku.ca.
authors.forename: Magdalena M
authors.initials: MM
authors.lastname: Krol
authors.affiliation: Oregon Health & Science University, 20000 NW Walker Road, Beaverton, OR, USA. Electronic address: rick.johnson.phd@gmail.com.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Johnson
authors.affiliation: University of Toronto, Department of Civil Engineering, Toronto, ON M5S 1A4, Canada. Electronic address: sleep@ecf.utoronto.ca.
authors.forename: Brent E
authors.initials: BE
authors.lastname: Sleep
mesh_terms: D018481:Convection; D060587:Groundwater / Q000737:chemistry; D006361:Heating; D008956:Models, Chemical; D016062:Porosity; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*
chemical_list: D012987:Soil; D012989:Soil Pollutants
keywords: Buoyancy ratio; Contaminant transport; Peclet number; Rayleigh number; Thermal remediation