HR: 0830h
AN: H51A-03    [Abstracts]
TI: An ELLAM approximation for advective-dispersive transport with combined, nonlinear equilibrium and nonequilibrium sorption
AU: * Farthing, M W
EM: matthew_farthing@unc.edu
AF: UNC Department of Environmental Sciences and Engineering, CB #7431, Rosenau Hall, Chapel Hill, NC 27599 United States
AU: Kees, C E
EM: chris_kees@ncsu.edu
AF: Center for Research in Scientific Computation, Department of Mathematics, North Carolina State University, Raleigh, NC 27695-8205 United States
AU: Russell, T F
EM: trussell@nsf.gov
AF: Department of Mathematics, University of Colorado at Denver, P.O Box 173364 Campus Box 170, Denver, CO 80217 United States
AU: Miller, C T
EM: casey_miller@unc.edu
AF: UNC Department of Environmental Sciences and Engineering, CB #7431, Rosenau Hall, Chapel Hill, NC 27599 United States
AB: We consider an Eulerian-Lagrangian localized adjoint method (ELLAM) applied to nonlinear model equations governing solute transport and sorption in porous media. Solute transport in the aqueous phase is modeled by standard advection and hydrodynamic dispersion, while two types of solid phase are distinguished --- a fraction which achieves equilibrium with the aqueous phase quickly, and another which does not. The rapidly sorbing fraction is modeled using a local equilibrium assumption, while a first-order rate expression is used for the slowly sorbing fraction. In both cases, the sorption isotherms are assumed to be nonlinear. This can be a difficult problem to model numerically for several reasons. Depending on the choice of isotherms, solutions may exhibit self-sharpening fronts and finite speed of propagation. The presence of both equilibrium and non-equilibrium sorption can be challenging for Eulerian-Lagrangian methods, since information may propagate along different characteristic directions in the space-time domain. Here, we present an implementation of a finite element ELLAM discretization in both fully coupled and operator-split frameworks for the reactive transport model. We then evaluate our method for several test problems spanning a range of auxiliary and physical conditions and compare its performance to more standard approaches.
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2005 Joint Assembly