HR: 0800h
AN: H21D-1041    [Abstracts]
TI: Assessment of Assumption Validity in the Colloid Filtration Theory: Direct Numerical Simulation of Colloids and Comparison of Filtration Equations
AU: * Nelson, K E
EM: knelson@ucdavis.edu
AF: University of California, Civil and Environmental Engineering, One Shields Ave. , Davis, CA 95616 United States
AU: Ginn, T R
AF: University of California, Civil and Environmental Engineering, One Shields Ave. , Davis, CA 95616 United States
AB: Critical assumptions of the colloid filtration theory (CFT) are examined via (a) a fully Lagrangian trajectory analysis within Happel's Sphere-in-Cell porous media model; (b) a comparison of different forms of the so-called filtration equation. The Lagrangian simulation technique incorporates all transport mechanisms of the classical CFT, including Brownian motion. Simulation results for the collection efficiency (i.e., the fraction of particles flowing towards the collector that make contact with the collector) suggest that the classical CFT assumption of independence for all transport mechanisms is not valid for Brownian particles. Additional assumptions inherent in the commonly used form of the filtration equation are examined by looking at the equation's derivation as well as the derivation of alternative forms of the filtration equation. The practical implications of using the different possible forms of the filtration equation for experimentally based evaluations of the sticking (or collision) efficiency and collection efficiency are discussed. Included in this discussion is an assessment of the conditions under which the commonly used approximate form of the filtration equation is valid. Also, the advantages of using a Lagrangian methodology for computing the CFT transport step are discussed, with an emphasis on the development of new mechanistic theories for the transport and deposition of bacterial colloids in saturated porous media.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1875 Unsaturated zone
DE: 1045 Low-temperature geochemistry
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting