520 likes | 632 Views
The FLASH Code Parallel AMR Made Easy. Tomek Plewa. LACSI Symposium Santa Fe, 10/12/2004. FLASH Center Astrophysics as primary application Verification and Validation activities External contributors and users. Outline. FLASH Code View from the outside Source tree and functionality
E N D
The FLASH CodeParallel AMR Made Easy Tomek Plewa LACSI Symposium Santa Fe, 10/12/2004
FLASH Center Astrophysics as primary application Verification and Validation activities External contributors and users Outline FLASH Code • View from the outside • Source tree and functionality • User level • Problem configuration • Intra-module modifications • Developer level • Extending the source tree • Inter-module communications Summary
Target Applications Compact accreting stars (white dwarf, neutron star) Reactive hydrodynamics (DNS or subgrid model) Initial conditions close to hydrostatic equilibrium (self-gravity) Complex EOS (dense nuclear matter) FLASH Application: Astrophysics Example: Type Ia Supernova • Massive white dwarf • Subgrid model for nuclear flame • Self-gravity • Degenerate EOS
Length scales in White Dwarf Deflagration Before 2000 Now BG/L
FLASH Verification & Validation Program Verification: solving equations right Validation: solving the right equations Verification ranging from simple analytic problems to code-code comparison. Validation: no direct access to experiments, use scaling laws Absolutely NO culture of validation in astrophysics!
Experimental time series, water/glycol fog visualization of SF6 mole fraction. Images correspond to 50, 190, 330, 470, 610, and 750 ms after shock impact Composite image does not preserve time-distance relationship FLASH V&V Complete Example
AMR-generated Timestep-dependent Signal CFL=0.8 CFL=0.4 CFL=0.2
FLASH As An Open Source Research Code FLASH is community code, freely (with minimal restrictions) available for research External contribution: shock-cylinder experiment (Jacobs, LANL)
FLASH Code Primary objective To create robust, reliable, efficient and expandable code, that stands the test of time and users. Primary characteristics parallel adaptive mesh (possibly different mesh packages) block-structured (currently) multi-physics (hydro, MHD, SRHD, gravity, particles…) Fortran 9x portable freely accessible documented & actively maintained
FLASH Portability: BG/L • Successful early runs up to 2048 processors Communication is scaling well. Test size limited by small number of available processors. • Large runs scheduled Several days of 16K-32K processors. • Focusing on FLOPS Make up for slower CPUs, beta-compilers
FLASH Unit Hierarchy API/ Stubs Common API Impl API impl API impl API impl Wrapper Wrapper Wrapper kernel kernel kernel
Summary • Overall architecture • Unit types • Unit architecture • Near future
Summary: Architecture Config files define components Unit Architecture API Inheritance Data management Setup tool assemble application Driver module organize interactions
Summary: Units Types • Physics hydro gravity • Infrastructure driver grid I/O • Utility profiler runtime visualization • Data analysis Fidlr flashview