Livermore scientists combine experiments and simulations to predict how systems will perform under a variety of conditions and to help researchers understand the behavior of materials under extreme conditions and the interaction of materials with radiation. This predictive capability is particularly important for stockpile stewardship, NNSA's program to ensure the safety and reliability of the nation's nuclear stockpile.
As part of the Laboratory's research in basic and applied physics, LLNL scientists conduct computer simulations in the following areas:
In many ways, simulation is as important as theory and experiment because it allows scientists to do extensive trial and error computationally, eliminating the financial costs and schedule delays of preparatory experiments.
When experiments are conducted, they are tightly focused on getting specific information that is then put back into computer models, making them more accurate. For instance, while it is possible to create some conditions important to the study of HEDP in the laboratory, these experiments are extremely expensive to perform and challenging to diagnose. Computer simulations can help overcome many of those obstacles and even be extended to regimes not accessible in the laboratory. Similarly, computer simulations are used to supplement the theoretical modeling of systems for which closed form analytic solutions are not possible.
Scientists at LLNL use various simulation codes to study a wide variety of topics. [See the Computer Codes page for more information about the codes WCI uses.]The simulation codes make use of several support libraries that deal with the equations of state, strength characteristics, and opacities of the materials being simulated as well as nuclear data libraries help the codes model nuclear reactions. Data from laboratory experiments are used to validate LLNL's ability to predict the behavior of complex physical systems. This predictive capability plays a crucial role in stockpile stewardship, NNSA's program to ensure the safety and reliability of the nation's nuclear stockpile.
Kim Cupps, Livermore Computing Division Leader, and Adam Bertsch, BlueGene Team Lead, discuss progress on the 20-petaFLOPS Sequoia machine deployed at LLNL in the fall of 2012.
Livermore Computing is crucial to WCI's mission and is home to a first-class computational infrastructure that supports the computing requirements of the WCI's research scientists. LC develops solutions (in collaboration with tri-lab partners at Los Alamos and Sandia National Laboratories) that create a functional problem-solving environment for high-performance computers under the Advanced Simulation and Computing (ASC) Program. [More about Livermore's High-Performance Computing]
SND scientists systematically check and review software throughout the software life-cycle in a verification and validation (V&V) process to ensure the credibility of codes and models, quantify confidence in calculation results, and measure the progress in the predictive capabilities. [More about V&V. See also Uncertainty Quantification.]