# High performance computations for large scale simulations of subsurface multiphase fluid and heat flow

## Abstract

TOUGH2 is a widely used reservoir simulator for solving subsurface flow related problems such as nuclear waste geologic isolation, environmental remediation of soil and groundwater contamination, and geothermal reservoir engineering. It solves a set of coupled mass and energy balance equations using a finite volume method. This contribution presents a parallel version of TOUGH2. The parallel implementation first partitions the unstructured computational domain. For each time step, a set of coupled non-linear equations is solved with Newtonian iteration. In each Newtonian step, a Jacobian matrix is calculated and an ill-conditioned, non-symmetric linear system is solved using a pre-conditioned iterative solver. Communication is required for convergence tests and data exchange across partitioning borders. Parallel performance results on a Cray T3E-900 are presented for two real application problems arising in the Yucca Mountain nuclear waste site study. The execution time is reduced from 7504 seconds on two processors to 126 seconds on 128 processors for a 2D problem involving 52,752 equations. For a larger 3D problem with 293,928 equations the time decreases from 10055 seconds on 16 processors to 329 seconds on 512 processors.

- Authors:

- Publication Date:

- Research Org.:
- Lawrence Berkeley National Lab., CA (US)

- Sponsoring Org.:
- USDOE Director, Office of Science (US)

- OSTI Identifier:
- 787077

- Report Number(s):
- LBNL-44693

R&D Project: 3659D2; TRN: US0110572

- DOE Contract Number:
- AC03-76SF00098

- Resource Type:
- Journal Article

- Journal Name:
- The Journal of Supercomputing

- Additional Journal Information:
- Journal Volume: 18; Journal Issue: 3; Other Information: Journal Publication Date: March 2001; PBD: 1 Sep 1999

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; PERFORMANCE; RADIOACTIVE WASTE FACILITIES; SIMULATORS; YUCCA MOUNTAIN; T CODES; MULTIPHASE FLOW; HEAT TRANSFER; NEWTON METHOD; RADIOACTIVE WASTE DISPOSAL

### Citation Formats

```
Elmroth, E., Ding, C., and Wu, Y.-S.
```*High performance computations for large scale simulations of subsurface multiphase fluid and heat flow*. United States: N. p., 1999.
Web.

```
Elmroth, E., Ding, C., & Wu, Y.-S.
```*High performance computations for large scale simulations of subsurface multiphase fluid and heat flow*. United States.

```
Elmroth, E., Ding, C., and Wu, Y.-S. Wed .
"High performance computations for large scale simulations of subsurface multiphase fluid and heat flow". United States.
```

```
@article{osti_787077,
```

title = {High performance computations for large scale simulations of subsurface multiphase fluid and heat flow},

author = {Elmroth, E. and Ding, C. and Wu, Y.-S.},

abstractNote = {TOUGH2 is a widely used reservoir simulator for solving subsurface flow related problems such as nuclear waste geologic isolation, environmental remediation of soil and groundwater contamination, and geothermal reservoir engineering. It solves a set of coupled mass and energy balance equations using a finite volume method. This contribution presents a parallel version of TOUGH2. The parallel implementation first partitions the unstructured computational domain. For each time step, a set of coupled non-linear equations is solved with Newtonian iteration. In each Newtonian step, a Jacobian matrix is calculated and an ill-conditioned, non-symmetric linear system is solved using a pre-conditioned iterative solver. Communication is required for convergence tests and data exchange across partitioning borders. Parallel performance results on a Cray T3E-900 are presented for two real application problems arising in the Yucca Mountain nuclear waste site study. The execution time is reduced from 7504 seconds on two processors to 126 seconds on 128 processors for a 2D problem involving 52,752 equations. For a larger 3D problem with 293,928 equations the time decreases from 10055 seconds on 16 processors to 329 seconds on 512 processors.},

doi = {},

journal = {The Journal of Supercomputing},

number = 3,

volume = 18,

place = {United States},

year = {1999},

month = {9}

}