The Community for Technology Leaders
SC Conference (1999)
Portland, Oregon, USA
Nov. 13, 1999 to Nov. 18, 1999
ISBN: 1-58113-091-0
pp: 52
Erik Elmroth , Lawrence Berkeley National Laboratory
Chris Ding , Lawrence Berkeley National Laboratory
Yu-Shu Wu , Lawrence Berkeley National Laboratory
Karsten Pruess , Lawrence Berkeley National Laboratory
TOUGH2 is a widely used simulation package for solving groundwater flow related problems such as nuclear waste isolation, environmental remediation, and geothermal reservoir engineering. It solves a set of coupled mass and energy balance equations using a finite volume method. The parallel implementation first partitions the unstructured computational domain. For each time step, a set of coupled non-linear equations is solved with Newton iteration. In each Newton step, a Jacobian matrix is calculated and an ill-conditioned non-symmetric linear system is solved in parallel using a preconditioned iterative solver. Communication is required for convergence tests and data exchange across partitioning borders. A real problem with 17,584 blocks and 43,815 connections indicates good scalability properties. From 2 to 128 processors on Cray T3E, the solution time is reduced from 7984 to 126 seconds. Improved parallel performance is expected for larger problems with 10<sup>5</sup>-10<sup>6</sup> blocks in a Yucca Mountain nuclear waste site study.
Ground water flow, grid partitioning, iterative linear solvers, preconditioners

E. Elmroth, C. Ding, K. Pruess and Y. Wu, "A Parallel Implementation of the TOUGH2 Software Package for Large Scale Multiphase Fluid and Heat Flow Simulations," SC Conference(SC), Portland, Oregon, USA, 1999, pp. 52.
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