11/12/2008 Colloquium - Keni Zhang

Keni Zhang Lawrence Berkeley National Laboratory

Event Info

Title:  A Domain Decomposition Approach for Large-scale Multiphase Flow Simulation ---An Introduction to TOUGH2-MP

Date: Nov 12, 2008
Location: 3105 Etcheverry Hall
Time: 4-5pm

Abstract

Large-scale simulations for multiphase fluid flow and heat flow are urgently needed for solving many environmental and resource problems, such as nuclear waste disposal, CO2 geologic sequestration, environmental assessment and remediation, geothermal reservoir engineering, and gas hydrate investigation. Because these simulations all require intensive computational efforts, many studies are limited by problem complexity and scale. With the growing popularity of multi-core CPUs, Linux clusters, and super-computers, the need for parallel processing methods will be a distinct advantage. In this study, we develop a domain decomposition approach for large-scale multiphase simulations using parallel computation. The approach partitions simulation domain to small sub-domains. The model will be simulated integrally but using multiple processes. Each process will be in charge of one portion of the simulation domain for updating thermophysical properties, assembling mass and energy balance equations, solving linear equation systems, and performing other local computations. The linear-equation systems are solved in parallel by multiple processes with a parallel linear solver. The multiple processes are run in parallel on shared- or distributed memory multiple-CPU computers, or on single-CPU computers. A hybrid approach, running multiple processes in each CPU and using multiple CPUs, may get additional speedup. A very efficient inter-process communication scheme has been developed. The new approach was implemented into the TOUGH2 code, a general-purpose numerical simulation program for multi-dimensional fluid and heat of multiphase, multi-component flows in porous and fractured media.

Speaker Biography

Dr. Keni Zhang has been working at the Earth Sciences Division of Lawrence Berkeley National Laboratory since 2000. He is the main author of several popular parallel simulators including TOUGH2-MP, TMVOC-MP, and parallel TOUGH+HYDRATE. In the past several years he has been extensively involved in the large-scale multiphase flow simulations for nuclear waste disposal, CO2 geological sequestration, and gas hydrate studies. He is one of the key members in the development of the Yucca Mountain unsaturated zone site-scale models.