A simple numerical approach for assessing coupled transport processes in partitioning systems

Recent concepts in the solution of multidomain equation systems are applied to the problem of distinct transport processes coupled over geometrically disjoint domains. The (time dependent) transport equations for the composit e system are solved using a simple domain decomposition approach, with para llel implementations of detailed Schwarz balances for the system subdomain interfaces. An existing numerical partial differential equation (PDE) solve r is coupled with the interface algorithms to provide a code capable of han dling a wide range of dynamical equations within the subdomains. Interface partitioning conditions corresponding to sharply discontinuous Dirichlet co nstraints. and to (discontinuous) rate-limited Neumann constraints are also incorporated into the code. A variety of transport operators can be handle d simply by altering the equation system code block. The code is validated against analytical solutions for representative parabolic transport equatio ns including recent solutions for diffusive transport in partitioning lamin ates, useful for describing the movement of chemical species in composite m aterials. The code is then applied to an example problem of coupled multiph ase chemical transport in a variably saturated soil column with a low-perme ability capping. (C) 2001 Elsevier Science Inc. All rights reserved.