1 / 7

gravitySimulator Beyond the Million Body Problem

gravitySimulator Beyond the Million Body Problem. Stefan Harfst and David Merritt Rochester Institute of Technology. Collaborators: Rainer Spurzem (Heidelberg) Peter Berczik (Heidelberg/Kiev) Simon Portegies Zwart (Amsterdam) Alessia Gualandris (Amsterdam) Hans-Peter Bischof (RIT).

zelia
Download Presentation

gravitySimulator Beyond the Million Body Problem

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. gravitySimulatorBeyond the Million Body Problem Stefan Harfst and David Merritt Rochester Institute of Technology Collaborators: Rainer Spurzem (Heidelberg) Peter Berczik (Heidelberg/Kiev) Simon Portegies Zwart (Amsterdam) Alessia Gualandris (Amsterdam) Hans-Peter Bischof (RIT)

  2. Modelling Dense Stellar Systems • one approach: direct N-body simulations • exact but very compute-intensive ~O(N2) • many problems require large N • e.g. the evolution of binary Black holes • “empty losscone” is artificially repopulated by two-body scattering unless N > 106

  3. How to deal with large N • A standard Supercomputer • Special-purpose hardware • GRAvity PipEline (GRAPE) • Customed-designed pipelines for force calculations • Very fast (~1 TFlops) • Limited particle numbers (< 1/4 million) • Cost: ~$50K + extras (GRAPE-6) (J. Makino, T. Fukushige)

  4. mini-GRAPEs (GRAPE-6A) The GRAPE cluster N < 131,072

  5. GRAPE cluster RIT’s gravitySimulator is operational since Feb 2005 • 32 dual 3GHz-Xeon nodes • 32 GRAPE-6A’s • 14 Tbyte RAID • low-latency Infiniband interconnects (10Gbps) • Speed: 4 TFlops • N up to 4 Million particles • Cost: $0.5x106 • Funding: NSF/NASA/RIT • Next largest: • 24 nodes (University of Tokyo) • soon 32 nodes (Heidelberg)

  6. store local particles • select active particles • collect all active particles • compute local force and sum over all nodes GRAPE PC The Code and Performance • new parallel direct-summation code • fourth-order Hermite integrator • individual, block time steps • achieves best performance • for small particle numbers communication dominates • efficiencies are between 60% (many processors) and 90% (few processors) For details see poster

  7. Visualization of N-Body Simulations in collaboration with Hans-Peter Bischof (RIT) • new software package “Spiegel” • GUI to plot N-body data and make movies • See Poster for details

More Related