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A sequential partly iterative approach for multicomponent reactive transport with CORE2D
| Content Provider | Semantic Scholar |
|---|---|
| Author | Samper, Javier Xu, Tianfu Yang, Changbing |
| Copyright Year | 2008 |
| Abstract | CORE V4 is a finite element code for modeling partly or fully satu r ed water flow, heat transport and multicomponent reactive solute transport under both local chem ical quilibrium and kinetic conditions. It can handle coupled microbial processes and geochemi cal reactions such as acid-base, aqueous complexation, redox, mineral dissolution/pre cipitation, gas dissolution/exsolution, ion exchange, sorption via linear and nonlinear isother ms, sorption via surface complexation. Hydraulic parameters may change due to mi neral precipitation/dissolution reactions. Coupled transport and chemical equations are solved by using sequential iterative approaches. A sequential partly-iterative approach (SPIA) is pre ent d which improves the accuracy of the traditional sequential noniterative approach (SNIA) and is more efficient than the general sequential iterative approach (SIA). While SNIA leads to a substantial saving of computing time, it introduces numerical errors which are especial ly large for cation exchange reactions. SPIA improves the efficiency of SIA because the it erat on between transport and chemical equations is only performed in nodes with a large mass tra nsfe between solid and liquid phases. The efficiency and accuracy of SPIA are compared t o those of SIA and SNIA using synthetic examples and a case study of reactive transport through the Llobregat Delta aquitard in Spain. SPIA is found to be as accurate as SIA while re quiring significantly less CPU time. In addition, SPIA is much more accurate than SNIA with only a minor increase in computing time. A further enhancement of the efficiency of SPIA is achieved by improving the efficiency of the Newton-Raphson method used for solving chemical equat ions. Such an improvement is obtained by working with increments of log-concentrati ons and ignoring the terms of the Jacobian matrix containing derivatives of activity coefficients. A proof is given for the symmetry and non-singularity of the Jacobian matrix. Numerical an lyses performed with synthetic examples confirm that these modifications improve the ef ficiency and convergence of the iterative algorithm. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://cloudfront.escholarship.org/dist/prd/content/qt05m9h244/qt05m9h244.pdf?t=li623a |
| Alternate Webpage(s) | https://digital.library.unt.edu/ark:/67531/metadc927984/m2/1/high_res_d/965368.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
