190 likes | 292 Views
Introduction to the GRAPE. Numerical Methods for Dense Stellar Systems. N-body : direct integration of the equations of motion Fokker-Planck : direct integration of the Fokker-Planck equation Monte-Carlo : particle-based method which uses
E N D
Numerical Methods for Dense Stellar Systems • N-body : direct integration of the equations of motion • Fokker-Planck : direct integration of the Fokker-Planck • equation • Monte-Carlo : particle-based method which uses • Monte-Carlo to apply relaxation • in the Fokker-Planck approximation • Gas model : cluster modeled as conducting gas • Hybrid methods : gas+MC, FP+N-body
The GRAPE project • GOAL : • Design and build specialized hardware for • simulation of stellar systems. • Rationale : • You can do larger simulations (better resolution) • for the same amount of money.
History of the GRAPE TABLE-1 Low-Precision machines Machine Year Peak speed GRAPE-1 1989 240 Mflop/s, GRAPE-3 1991 15 Gflop/s GRAPE-5 1998/9 ~ 1Tflop/s TABLE-2 High-Precision machines Machine Year Peak speedGRAPE-2 1990 40Mflop/s HARP-1 1993 180 Mflop/s GRAPE-4 1995 1 Tflop/s GRAPE-6 2002 64 Tflop/s
Sciences with the GRAPE • Solar system / Planetary formation • Star-forming region / Open clusters • Globular clusters • Galactic dynamics/ Galactic nuclei • Galaxy formation • Star formation • Clusters of Galaxies / Cosmology (CDM halo)
More than just N-body • SPH • “GRAPE-SPH” - Nakasato & Nomoto ,Matthias Steinmetz & Klaus Dolag ,Volker Springe • “Tree-GRAPE-SPH” • MHD“Grape-MSPH” - Dolag et al. (1991, 2002) • SPH simulations of magnetic fiels in galaxy clusters. • K. Dolag. (A&A 348, 351, 1999) • PM • “Grape + PM” - Andreas Huss
Constructing a GRAPE Cluster • 6,900,000 Yen for each GRAPE6-BLX64 board • Each BLX64 has 4 GRAPE chips • Total 132 Gflops • 3,000,000 Won for each host PC • Two 2.0GHz dual-core Xeons, 1 GB memory • 3,800,000 Won for one server PC • Two 2.0GHz dual-core Xeons, 1 GB memory
The Korean GRAPE Consortium • 이형목 교수님 : 구매 진행 중 • 2007 : 4 BLX64’s • 2008 : 4 BLX64’s or DR ? • SRC 멤버 : 3월 구매 예정 • 2007 : 4 BLX64’s • 2008 : 4 BLX64’s or DR ? • 공동연구 과제 신청? • 학진 기초과학 공동연구 : 1억/년, 최대 3년 (3월 신청) • 과학재단 특정기초 :1억/년, 최대 5년 (5월 신청)
Proposed Research Topics • Galactic Dynamics • Galactic warps : triaxial live halo • Galaxy interaction and evolution • Galactic Center Hydrodynamics • 200-pc molecular ring (the Central Molecular Zone) • 5-pc molecular ring (the Circumnuclear Ring) • Stellar Dynamics • Evolution of the globular cluster mass function • The Arches cluster • Future Plans • Development of new codes (Monte Carlo simulations + GRAPE) • Planetary dynamics