HR: 1340h
AN: H23G-1697    [Abstracts]
TI: The Concept of Tensorial Connectivity-Tortuosity for Multiple Fluids to Describe Saturation- Dependent Anisotropy in Hydraulic Conductivity
AU: * Zhang, F
AF: Hydrology Group, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, United States
AU: Oostrom, M
EM: mart.oostrom@pnl.gov
AF: Hydrology Group, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, United States
AU: Ward, A
AF: Hydrology Group, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, United States
AB: Natural geological formations are heterogeneous and often anisotropic. Numerous researches have found that the anisotropy in hydraulic conductivity is dependent on fluid saturation. The tensorial connectivity-tortuosity (TCT) concept has been used to describe the hydraulic conductivity tensor of unsaturated soils with saturation- dependent anisotropy. In this investigation, this concept is extended as the concept of tensorial connectivity- tortuosity for multiple fluids (TCT-MF) in unsaturated porous media. The hydraulic conductivity of each fluid in an anisotropic porous medium under unsaturated conditions is described in the form of a symmetric second-order tensor. The TCT-MF theory applies to the generalized hydraulic conductivity model and compatible types of saturation-pressure formulations. The model shows that the anisotropic coefficient of any one of the fluids is dependent only on the saturation of the fluid being considered but independent of the saturation of other fluids. The TCT-MF concept was tested using numerical experiments of infiltration in synthetic Miller-similar soils with four levels of heterogeneity and four levels of anisotropy. The synthetic soils were generated to be anisotropic by allowing the saturated hydraulic conductivity to have different correlation ranges for different directions of flow. The numerical experiments of infiltration of two liquid phases, i.e., water and the nonaqueous phase liquid (NAPL) carbon tetrachloride, were conducted. The results show that, similar to water in a two-fluid (air-water) system, NAPL retention curves in a three-fluid (air-NAPL-water) system were independent of flow direction but dependent on soil heterogeneity; the connectivity-tortuosity coefficients were functions of both soil heterogeneity and anisotropy. The TCT-MF model accurately described the unsaturated hydraulic function of each fluid of the anisotropic soils and can be combined into commonly used relative permeability functions for use in multifluid flow-and-transport numerical simulations.
DE: 1805 Computational hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2007 Fall Meeting