HR: 0800h
AN: H51F-0430    [Abstracts]
TI: Pore-Scale Simulation of Dispersion and Reaction Along a Transverse Mixing Zone
AU: * Acharya, R C
EM: hypon@uiuc.edu
AF: Department of Civil and Environmental Engineering, UIUC, 205 North Mathews Avenue (MC-250), Urbana, IL 61801 United States
AU: Valocchi, A J
EM: valocchi@uiuc.edu
AF: Department of Civil and Environmental Engineering, UIUC, 205 North Mathews Avenue (MC-250), Urbana, IL 61801 United States
AU: Willingham, T W
EM: thomas_willingham@yahoo.com
AF: Department of Civil and Environmental Engineering, UIUC, 205 North Mathews Avenue (MC-250), Urbana, IL 61801 United States
AU: Werth, C J
EM: werth@uiuc.edu
AF: Department of Civil and Environmental Engineering, UIUC, 205 North Mathews Avenue (MC-250), Urbana, IL 61801 United States
AB: Transverse dispersion plays an important role in determining the fate of conservative and reactive chemicals in porous media. Natural and engineered in-situ remediation relies on the mixing of reactive chemicals or nutrients, and several studies have demonstrated the important role played by transverse dispersion along the lateral fringe of the plume. Reactions are often fast reactions and are thus usually dispersion/diffusion limited; this leads to narrow reaction zones over small spatial scales. That means that without understanding pore-scale dispersion and product-formation processes due to mixing, large-scale equations cannot be formulated or improved. We report the results of numerical simulations to better understand the underlying processes of transport, mixing and reaction at the pore-scale. Attention is paid to the analysis of effects of advection velocity and grain shape and orientation on dispersion and product formation. The flow field is generated by the lattice-Boltzmann method and the transport is handled with a finite volume code. We illustrate our approach through a steady state system of two reactants injected side-by-side parallel to the mean flow direction. We first estimate the transverse dispersion coefficient through comparison of a continuum scale model to the pore-scale simulation of the spread of a nonreactive solute. We then simulate pore-scale advection and transverse diffusion for each chemical and compute the product formed by the reaction. We investigate whether use of the transverse dispersion coefficient gives the proper degree of mixing to accurately simulate the amount of product formed in the system. The results are compared with available experimental evidence and theoretical findings.
UR: http://www.geocities.com/acharya_ram/dispersresearch.pdf
DE: 0420 Biomolecular and chemical tracers
DE: 1705 Biogeosciences
DE: 1719 Hydrology
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1805 Computational hydrology
SC: Hydrology [H]
MN: Fall Meeting 2005