A Subgrid-Scale Stabilized Finite Element Method for Multicomponent Reactive Transport through Porous Media |
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Authors: | Changbing Yang Javier Samper |
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Institution: | 1.Bureau of Economic Geology,University of Texas at Austin,Austin,USA;2.University of La Coru?a,La Coru?a,Spain |
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Abstract: | Standard Galerkin finite element methods (GFEM) lack stability in solving advection-dominated solute transport in porous media.
They usually require prohibitively fine grids and extremely small time steps to solve for advection-dominated problems. The
algebraic subgrid-scale stabilized (ASGS) finite element method has been proved to overcome such problems for single-species
reactive transport. Its potential for dealing with multicomponent reactive transport has not yet been explored. Here we present
a numerical formulation of ASGS for steady and transient multicomponent reactive transport. Subgrid-scale transport equations
are solved first by using an ASGS approximation and their solutions are substituted back into the grid-scale equations. A
sequential iteration approach (SIA) is used to solve for coupled transport and chemical equations. Coupling of ASGS and SIA,
ASGS+SIA, has been implemented in a reactive transport code, CORE2D V4, and verified for conservative solute transport. ASGS+SIA has been tested for a wide range of 1-D transient multicomponent
reactive transport problems involving different types of chemical reactions such as: (1) Kinetically controlled aqueous species
degradation, (2) Kinetic mineral dissolution, (3) Serial-parallel decay networks, and (4) Cation exchange and pyrite oxidation
at local equilibrium. ASGS+SIA always provides accurate solutions and therefore offers an efficient option to solve for advection-dominated
multicomponent reactive transport problems. |
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Keywords: | Algebraic subgrid-scale approximation Stabilized method Multicomponent reactive transport Finite element Porous media Analytical solution |
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