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Simuler numériquement de la formation des galaxies dans l’univers. A realistic star formation model can be obtained using current computers. But box size is too small: simulations have to be stopped too early (z=3). 256 PE with 256Gb 10h -1 Mpc box size 512 3 particles 16384 3 AMR grid
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Simuler numériquement de la formation des galaxies dans l’univers . A realistic star formation model can be obtained using current computers. But box size is too small: simulations have to be stopped too early (z=3). 256 PE with 256Gb 10h-1 Mpc box size 5123 particles 163843 AMR grid Cooling & star formation We need more computing power to go to larger boxes ! Our goal: 40h-1 Mpc box 20483 particles 655363 AMR grid Gas density We need: 4096 processors 8 Tb memory 500h wall time 10h-1 Mpc Stellar density
Horizon Project: a French initiative to promote large scale computing in cosmology Who ? 30 scientists 6 institutes 2 engineers, 2 post-docs 10 PhD students What ? Parallel computing Visualization tools Galaxy formation physics Theoretical Virtual Observatory How ? 1/2 M€ hardware support 1/2 TéraFlops dedicated computer 6 nodes grid of AMD 64 quads http://www.obspm.fr/horizon • Objectives of the Horizon Project: • Prepare, run and analyze large scale, massively parallel, cosmological simulations • Build the necessary infrastructure to optimize scientific exploitation of such simulations • Promote among French students and scientists the expertise in computational cosmology RAMSES and ENZO: 2 complementary hydro + N body AMR codes for extreme computing RAMSES Teyssier, R. A&A, 2002, 385, 337 Tree based AMR code Unsplit high-order Godunov Galaxy formation physics Adaptive domain decomposition using “space filling curve” MPI and F90 ENZO http://cosmos.ucsd.edu/enzo/ Patch based AMR code Time split PPM Galaxy formation physics Adaptive load balancing at subgrids creation time MPI, F90 and C++ Present: Good scalability up to 512 processors and 10243 particles Cooling & UV heating using external spectrum Star formation and supernovae feedback Objectives: run RAMSES or/and ENZO up to 4096 processors Self-consistent cooling & UV heating (spectrum & metals) Metal enrichment using galactic winds