T2CG1, a package of preconditioned conjugate gradient solvers for TOUGH2

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Most of the computational work in the numerical simulation of fluid and heat flows in permeable media arises in the solution of large systems of linear equations. The simplest technique for solving such equations is by direct methods. However, because of large storage requirements and accumulation of roundoff errors, the application of direct solution techniques is limited, depending on matrix bandwidth, to systems of a few hundred to at most a few thousand simultaneous equations. T2CG1, a package of preconditioned conjugate gradient solvers, has been added to TOUGH2 to complement its direct solver and significantly increase the size of problems ... continued below

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18 p.

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Moridis, G.; Pruess, K. & Antunez, E. March 1, 1994.

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Description

Most of the computational work in the numerical simulation of fluid and heat flows in permeable media arises in the solution of large systems of linear equations. The simplest technique for solving such equations is by direct methods. However, because of large storage requirements and accumulation of roundoff errors, the application of direct solution techniques is limited, depending on matrix bandwidth, to systems of a few hundred to at most a few thousand simultaneous equations. T2CG1, a package of preconditioned conjugate gradient solvers, has been added to TOUGH2 to complement its direct solver and significantly increase the size of problems tractable on PCs. T2CG1 includes three different solvers: a Bi-Conjugate Gradient (BCG) solver, a Bi-Conjugate Gradient Squared (BCGS) solver, and a Generalized Minimum Residual (GMRES) solver. Results from six test problems with up to 30,000 equations show that T2CG1 (1) is significantly (and invariably) faster and requires far less memory than the MA28 direct solver, (2) it makes possible the solution of very large three-dimensional problems on PCs, and (3) that the BCGS solver is the fastest of the three in the tested problems. Sample problems are presented related to heat and fluid flow at Yucca Mountain and WIPP, environmental remediation by the Thermal Enhanced Vapor Extraction System, and geothermal resources.

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18 p.

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INIS; OSTI as DE94015159

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  • Other Information: PBD: Mar 1994

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  • Other: DE94015159
  • Report No.: LBL--35518
  • Grant Number: AC03-76SF00098
  • DOI: 10.2172/145291 | External Link
  • Office of Scientific & Technical Information Report Number: 145291
  • Archival Resource Key: ark:/67531/metadc619500

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  • March 1, 1994

Added to The UNT Digital Library

  • June 16, 2015, 7:43 a.m.

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  • April 5, 2016, 12:32 p.m.

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Moridis, G.; Pruess, K. & Antunez, E. T2CG1, a package of preconditioned conjugate gradient solvers for TOUGH2, report, March 1, 1994; California. (digital.library.unt.edu/ark:/67531/metadc619500/: accessed September 23, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.