ECONOMICS

Network Computer Services, Inc. (NCSI), the systems integrator and computing facilities manager for the Army High Performance Computing Research Center (AHPCRC), today reported record results on engineering and weather applications run on the Cray X1(TM) supercomputer system. An AHPCRC unstructured mesh computational fluid dynamics (CFD) application ran at a sustained speed exceeding one teraflop (one trillion calculations per second) on a Cray X1 supercomputer with 256-multistreaming processors (MSP). The application showed highly efficient, linear scaling across 252 MSPs, with sustained performance of more than 4.17 gigaflops (billions of calculations per second) per processor. This computation was performed on a mesh that contained 2.1 billion tetrahedral elements. 160 time steps were run in approximately five hours. The application required 665.7 gigabytes of memory. This CFD application is based on the finite element method with a fully coupled iterative equation solver incorporating matrix-free methods. The code utilizes the distributed memory parallel programming model and is implemented using MPI, C and Unified Parallel C. Using this code, AHPCRC researchers are able to perform CFD calculations on extremely large data sets with a high degree of refinement. Traditionally, CFD applications might use a mesh containing between 1 and 10 million tetrahedral elements. AHPCRC researchers, using the Cray X1, are now routinely performing simulations using meshes between 50 and 500 million elements and, as mentioned above, up to 2 billion elements in some cases. This increase in mesh size and refinement generally corresponds to an improvement in the accuracy of the results. NCSI also announced that it is demonstrating, at Supercomputing 2003, the use of the Fifth Generation Mesoscale Weather Forecast Model (MM5) on the Cray X1 to produce 5 kilometer resolution weather forecasts for the entire Continental United States (CONUS). MM5, which is used extensively within the United States and at certain international locations, the Cray X1 system produced a 24-hour weather forecast for the entire United States with 5-kilometer resolution (33 levels in the vertical) in 94 minutes. The demonstration uses pre-processing software that is part of the suite of MM5 tools. Output from the ETA-coordinate model run by the National Center for Environmental Prediction (NCEP) is being re-analyzed to produce the initial conditions and boundary data for MM5. The forecast is generated using 06Z and 12Z NCEP data. A forecast generates 53 gigabytes of output data. The forecasts are run on the 64 Cray X1 MSPs. In addition to the 5 kilometer daily forecast, output from a 2.5 kilometer CONUS simulated forecast for 18 September 2003 showing the landfall of hurricane Isabel is also being visualized at Supercomputing 2003. The output data for this 24-hour simulation is approximately 211 gigabytes. The 2.5 kilometer (with 33 vertical levels) CONUS simulation was for a 12-hour period and used 15 second time steps. The entire calculation ran in about 3.5 hours on 120 MSPs. The 2.5 km simulation was run as a feasibility study. The results of this study are currently being analyzed to verify the correctness of MM5 at such a fine grid spacing. Current operational weather models that cover all of the United States are typically run at a resolution of about 10 kilometers. The 5-kilometer model requires approximately 8 times as much computation as the 10-kilometer model and four times as much memory (20 billion bytes). The 2.5-kilometer model requires about 64 times as much computation, and 16 times as much memory, as a typical 10-kilometer run. "To our knowledge, no U.S. weather forecasting facility is currently producing weather forecasts across the entire country at this level of resolution in anything near three hours," according to Muzio. "This first full-production Cray X1 system, installed at the AHPCRC, already has demonstrated its ability to achieve breakthrough performance results while running Army applications in computational fluid dynamics, computational mechanics and battlefield weather forecasting that are of great importance to the defense of the United States," Muzio said. Please the visit the AHPCRC booth (#304) at the Supercomputing 2003 conference in Phoenix, November 17-21, 2003 for additional information and on-line demonstrations.