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Groundbreaking Computer Simulation Work Published

Computational and combustion scientists in two divisions of the Lawrence Berkeley National Laboratory (Berkeley Lab) have earned national recognition in the Proceedings of the National Academy of Sciences (PNAS) with a cover article about groundbreaking computer simulations of turbulent flames.

The research by scientists in Berkeley Lab's Center for Computational Sciences and Engineering and in the Environmental Energy Technologies Division has led to a three-dimensional combustion simulation of unmatched size without the need for turbulence or turbulence-chemistry interaction models. The PNAS article shows that the simulation closely matches flame behavior in an actual combustion experiment.

Gaining a better understanding of combustion, which powers everything from automobiles to aircraft to power generating plants, can help improve the efficiency of those systems as well as reduce the amount of pollution produced by burning fossil fuels.

Image of the v-flame

Figure 1. Scientists with Berkeley Lab's Center for Computational Science, and Engineering and the Environmental Energy Technologies Division, have created unique three-dimensional, time-dependent simulations of turbulent V-flames to gain a better understanding of combustion.

"Although collaborations between computational scientists and experimentalists are becoming increasingly common, the results from this project clearly demonstrate how scientific computing is coming into its own as an essential component of scientific discovery," said Horst Simon, Associate Laboratory Director for Computing Sciences at Berkeley Lab. "The simulation is unprecedented in several aspects: the number of chemical species included, the number of chemical processes modeled, and the overall size of the flame. This is truly breakthrough computational science."

The article describes the simulation of "a laboratory-scale turbulent rod-stabilized premixed methane V-flame. This simulation, which models a full laboratory-scale flame by using detailed chemistry and transport, encompasses a domain more than three orders of magnitude larger in volume than that of any previous efforts and represents a major increment in simulation complexity."

The Berkeley Lab combustion simulations use a different mathematical approach than has typically been used. Most other combustion simulations without turbulence models use equations that include sound waves, which makes these models very computationally expensive. Because of the cost, such simulations often have been limited to only two dimensions, to scales smaller than a centimeter, or to just a few carbon species and reactions. By contrast, the Berkeley Lab researchers have modeled a three-dimensional flame about 12 centimeters high that consists of 19 chemical species and 84 fundamental chemical reactions, producing results that can be compared directly with experimental diagnostics.

The Berkeley Lab group has developed an algorithmic approach that combines "low Mach-number equations," which remove sound waves, with "adaptive mesh refinement." The combined methodology strips away relatively unimportant aspects of the simulation and focuses computing resources on the most important processes that model flame behavior. Developed with the support of the Applied Mathematics Program of the U.S. Department of Energy (DOE) Office of Advanced Scientific Computing Research, the group's algorithms have slashed computational costs for combustion simulations by a factor of 10,000. Even so, the combustion simulation required substantial computing power, running for about 1,000 hours on 256 processors of the IBM SP supercomputer at DOE's National Energy Research Scientific Computing Center at Berkeley Lab.

The PNAS article, "Numerical simulation of a laboratory-scale turbulent V-flame," was written by John B. Bell, Marc S. Day, Ian G. Shepherd, Matthew R. Johnson, Robert K. Cheng, Joseph F. Grcar, Vincent E. Beckner, and Michael J. Lijewski and appeared in the July 19, 2005 edition. Cheng and Shepard are the EETD authors.

— Jon Bashor

Jon Bashor is in Berkeley Lab's Computing Sciences Directorate.

For more information about the combustion research, contact:

  • Robert Cheng
  • (510) 486-5438; Fax (510) 486-7303

The research described in the PNAS article was supported by the Applied Partial Differential Equations Center of DOE's Scientific Discovery through Advanced Computation program. The combustion experiments were supported by DOE's Office of Science in the Office of Basic Energy Sciences. The work also received support from Cristina Siegerist and Wes Bethel of Berkeley Lab's Visualization Group.

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