HR: 1330h
AN: H32A-0511    [PDF]
TI: A Practical Multifluid Flow Model Including Mobile, Residual, and Entrapped NAPL
AU: * Oostrom, M
EM: mart.oostrom@pnl.gov
AF: Environmental Technology Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 United States
AU: White, M D
EM: mark.white@pnl.gov
AF: Environmental Technology Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 United States
AU: Lenhard, R J
EM: lenhrj@inel.gov
AF: Subsurface Science Initiative, INEEL, P.O. Box 1625, Idaho Falls, ID 83415 United States
AU: Wietsma, T W
EM: wietsma@pnl.gov
AF: Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 United States
AB: Flow of nonvolatile NAPL and aqueous phases that accounts for mobile, entrapped (water-occluded), and residual NAPL in variably saturated porous media is numerically modeled and compared against results from detailed laboratory-scale experiments. Residual saturation formation in the vadose zone is a process that is often ignored in multifluid flow simulators, which might cause an overestimation of the volume of NAPL that reaches the ground water. Mobile NAPL is defined as being continuous in the pore space and flows under a pressure gradient or gravitational body force. Entrapped NAPL is defined as being occluded by the aqueous phase, occurring as immobile ganglia surrounded by aqueous phase in the pore space and formed when NAPL is replaced by the aqueous phase. Residual NAPL is defined as immobile, non-water entrapped NAPL that does not drain from the pore spaces and is conceptualized as being either continuous or discontinuous. The numerical model is formulated on mass conservation equations for oil and water, transported via NAPL and aqueous phases through variably saturated porous media. To account for phase transitions, a primary variable switching scheme is implemented for the oil-mass conservation equation over three phase conditions: 1) aqueous or aqueous-gas with dissolved oil, 2) aqueous or aqueous-gas with entrapped NAPL, and 3) aqueous-free NAPL or aqueous-free NAPL-gas. Two laboratory-scale column experiments are modeled to verify the numerical model. Comparisons between the numerical simulations and experiments demonstrate the necessity to include the residual NAPL formation process in multifluid flow simulators. Pacific Northwest National Laboratory is operated by the Battelle Memorial Institute for the Department of Energy under Contract DE-AC06-76RLO 1830. This research is part of the Groundwater/Vadose Zone Integration Project funded through the U.S. Department of Energy's Richland Operations Office
DE: 1800 HYDROLOGY
DE: 1832 Groundwater transport
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting