A publication of the Advanced Simulation & Computing Division, NA-121.2, NNSA Defense Programs
June 2008
NA-ASC-500-08—Issue 7Printable Version
(~1.5MB PDF)
The Year So Far…
Editorial by Bob Meisner
The first half of this year has been one of significant success for the program in spite of the budget turmoil, achieved through the staunch determination of a world-class team spread across the labs. Your accomplishments continue to improve the way science and engineering are conducted, and I’d like to take this opportunity to recognize a few significant steps forward.
Roadrunner Fastest Computer on Earth
On May 26, 2008, the Roadrunner supercomputer achieved the long-sought supercomputing goal of performing more than a thousand trillion operations per second, or petaFLOPS. Roadrunner was built by IBM with funding from the NNSA for Los Alamos National Laboratory. Soon, a caravan of moving vans will transport Roadrunner from IBM to Los Alamos, where it will be installed in the Nicholas C. Metropolis Center for Modeling and Simulation.
NNSA Creates an Alliance to Pursue Computing at Extreme Scales
NNSA’s Advanced Simulation & Computing (ASC) program has established a high-performance capability computing partnership known as the NNSA Alliance for Computing at Extreme Scale (ACES). ACES is a joint venture between two New Mexico laboratories: Sandia National Laboratories and Los Alamos National Laboratory. As part of the Alliance, both laboratories will share intellectual capabilities and capitalize on their existing expertise in developing architectures and designs for future platforms. Los Alamos’s Strategic Computing Complex (SCC) facility will house high-performance capability computing assets needed to support NNSA’s ongoing stockpile stewardship mission, and to meet the ASC Roadmap timeline requirement for an exascale capability by 2018. The first of these ACES capability platforms will be named Zia and is targeted for installment in FY10. It will support the needs of all three NNSA’s laboratories.
Explosives at the Microscopic Scale Produce Shocking Results
The first quantum molecular dynamics simulation of a shocked explosive near detonation conditions to reveal what happens at the microscopic scale was recently announced by researchers from Lawrence Livermore National Laboratory and the Massachusetts Institute of Technology. What they found was quite riveting: the explosive, nitromethane, undergoes a chemical decomposition and a transformation into a semi-metallic state for a limited distance behind the detonation front. “Despite the extensive production and use of explosives for more than a century, their basic microscopic properties during detonation haven’t been unraveled,” said lead author Evan Reed in a January 2008 article in Nature Physics. “We’ve gotten the first glimpse of the properties by performing the first quantum molecular dynamics simulation.”
NIF Full-Beam Simulation on BlueGene/L a Success
Lawrence Livermore National Laboratory recently completed a parallel F3D (pF3D) simulation of a National Ignition Facility (NIF) 50-degree laser beam on the BlueGene/L computer. This is the first time that a simulation has modeled the full cross section of a NIF beam from the laser entrance hole to the hohlraum wall. Until now, simulating the entire beam cross section was beyond the reach of available computational resources. The BlueGene/L full-beam simulation provides a benchmark for evaluating the effects of approximating the beam by a central slab.
Progress in HEDP Code Consolidation
In connection with the ASC Integrated Codes strategy, and the associated code consolidation efforts to eliminate unnecessary duplication of capability, Sandia and Lawrence Livermore are transferring selected magneto-hydrodynamics (MHD) capabilities developed and implemented in Sandia’s ALEGRA code into Lawrence Livermore’s high energy density physics (HEDP) codes. An early success was achieved in this collaboration through implementation of a package from ALEGRA for ideal MHD modeling in the Lawrence Livermore KULL code.
ASC Contribution Featured in W80 QMU Analysis
A quantification of margins and uncertainties (QMU) study subject to both fully engulfing and directed-flux fire scenarios was performed under the Sandia ASC Verification and Validation program for the W80-0/1. This study employed the thermal analysis capabilities of Sandia’s SIERRA simulation software and the uncertainty quantification capabilities of Sandia’s DAKOTA software. Sandia’s Predictive Capability Maturity Model (PCMM) was used to assess the state of the physics-based computational models and the QMU analysis methods employed. The study also demonstrated new reaction rate chemistry models implemented in Sandia’s SIERRA Mechanics code and used experiment data acquired from W80-0/1 thermal tests in Sandia’s Radiant Heat Facility to assist with model validation.
New Error Estimator Deployed in Encore
Numerical error estimation and adaptive mesh refinement are important capabilities for solution verification in modeling and simulation studies and for efficient use of computing resources. A new generic error estimator that can be used in multiple Sandia codes has been recently added to Encore—the SIERRA Mechanics toolkit for verification and adaptive mesh refinement. The estimator is based on averaging of fluxes or stresses and is independent of the physics used in the code.
New V&V Capabilities Demonstrated in Neutron Generator Study
The recently developed ion beam focusing capabilities of the Aleph simulation tool were validated through comparisons to experimental data on gradients in high electrostatic fields. The project is jointly funded by the SNL ASC Verification and Validation program and Integrated Codes program. The Aleph code is being developed as the code platform for modeling the plasma source generation, as well as the acceleration and transport of the ionized plasma, in the high-voltage tube of neutron generators.
The recent validation study employed Sandia’s DAKOTA toolkit to explore the sensitivity of ion beam performance to variations in electron temperature, ion temperature, and accelerating voltage. The study used Sandia’s SIERRA/Encore software tool to perform comparisons of the Aleph simulation data with the experimental test data.
Sequoia: Supporting Urgent Stockpile Stewardship Computing Needs
The signing of Sequoia Critical Decision 1 (CD1) by NNSA Deputy Administrator Robert L. Smolen on March 26, 2008, allows Lawrence Livermore National Laboratory to release the Sequoia Request for Proposal (RFP) to the industry for bid. This development sets the program on a date-certain path for evaluation of RFP responses, vendor selection, contract negotiation, and acquisition of a new petascale computing resource.
The New Frontier of Research: Science at the Petascale
In early June 2008, while verifying the performance of the Los Alamos National Laboratory Roadrunner supercomputer, Los Alamos and IBM researchers used three different computational codes to test the machine: VPIC, SPaSM, and PetaVision. VPIC simulates plasma physics. For example, one application of VPIC is to simulate laser plasma interactions critical to understanding inertial confinement fusion at the National Ignition Facility. SPaSM simulations provide insight into fundamental materials and physics processes. PetaVision models the human visual system—mimicking more than one billion visual neurons and trillions of synapses. Scientists used PetaVision to reach a new computing performance record of a sustained 1.144 petaFLOPS.
Roadrunner in Running for TOP500 and Green500 Lists
Making it onto the TOP500 list of supercomputers is a much sought-after goal. At the end of May 2008, Roadrunner posted a peak performance of 1.026 petaFLOPS running the Linpack benchmark. The test consisted of solving linear equations involving more than 2 million equations and an equal number of unknowns.
Backup Internet Path Saves Los Alamos Connection
On April 15, 2008, a cut fiber cable near Santa Fe, NM, caused a complete loss of Internet connectivity at Los Alamos National Laboratory. Fortunately, LANL network engineers were able to activate a backup path within minutes, re-routing their Internet traffic across the DISCOM WAN and back onto ESNet in Livermore. The backup connection remained active for nearly 22 hours while the fiber cut was repaired. In most circumstances, this incident would have been disastrous, but thanks to the bidirectional backup path to the Internet developed by teams at LLNL and LANL and implemented just five weeks earlier, LANL was back online within minutes.
ASC Participates in First-Ever Office of Science HPC Symposium
ASC researchers were prominently represented in the first High Performance Computer Science Week (HPCSW), organized by DOE’s Office of Science in collaboration with the Krell Institute, held March 30 to April 4 in Denver, CO. The first half of the week featured a meeting of all principal investigators of the Office of Advanced Scientific Computing Research (OASCR) Computer Science projects, and the second week offered a comprehensive overview of the state of the art in HPC through one keynote, four panels, seven workshops, and two tutorials.
BlueGene/L Referenced As State-of-the-Art in College Textbook
BlueGene/L is referenced as an example of state-of-the-art supercomputing in a newly published college textbook, Understanding Computers Today and Tomorrow. The textbook, now in its 12th edition, is published by Cenage Learning as part of its Course Technology series. BlueGene/L is referenced with photos in a section on supercomputers and supercomputing clusters and again in a section on massively parallel processing. The text is edited by Deborah Morley and Charles S. Parker and sells in hard copy for about $85.
ASC Salutes
Martin Heinstein, a Distinguished Member of the Technical Staff in the Engineering Sciences Center at Sandia, leads the computational solid mechanics portion of Sandia’s SIERRA Mechanics development effort under ASC’s Integrated Codes/Engineering Codes program element. In the four years that Martin has served in this role, SIERRA Mechanics has moved from a loosely connected set of mechanics modules to a more tightly consolidated code system, which is reliable and robust, with dramatic performance increases and unique mechanics capabilities for Sandia’s diverse set of solid/structural mechanics applications. These capabilities have also been extended to applications across the nuclear weapons complex. With his ability to create innovative solutions to mechanics problems, Martin has been directly responsible for the successful development of many of these unique capabilities and for guiding the work of others in developing additional capabilities.
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