An ELLAM approximation for advective-dispersive ...

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XVI International Conference on Computational Methods in Water Resources (CMWR-XVI) Ingeniørhuset

An ELLAM approximation for advective-dispersive transport with nonlinear equilibrium and nonequilibrium sorption
Paper
Author:Matthew Farthing <matthew_farthing@unc.edu> (University of North Carolina)
Christopher Kees <christopher.e.kees@erdc.usace.army.mil> (US Army Corps of Engineers Engineer Research and Development Center)
Thomas Russell <trussell@nsf.gov> (University of Colorado at Denver)
Cass Miller <casey_miller@unc.edu> (University of North Carolina)
Presenter:Matthew Farthing <matthew_farthing@unc.edu> (University of North Carolina)
Date: 2006-06-18     Track: General Sessions     Session: General
DOI:10.4122/1.1000000397
DOI:10.4122/1.1000000398

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. 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 (FE-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.