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The Flash Code. From Applications to Design. From Design to Applications. Tomek Plewa on behalf of almost countless contributors The ASCI Flash Center Dept. of Astronomy & Astrophysics The University of Chicago July 22, 2002. http://flash.uchicago.edu. What Is the Flash Center?.

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The flash code

The Flash Code

From Applications to Design

From Design to Applications

Tomek Plewa

on behalf of almost countless contributors

The ASCI Flash Center

Dept. of Astronomy & Astrophysics

The University of Chicago

July 22, 2002

http://flash.uchicago.edu


What is the flash center

What Is the Flash Center?

  • Supported by the DOE ASCI/Alliances Program

  • Over $1,000,000 p.a. budget

  • 20 core researches, 30 contributors at different levels

  • Access to the most advanced computer technology

  • Close partners at UofC, ANL MCS, UCSC, UIUC

  • Collaboration with LLNL, LANL, LBNL, Sandia, ORNL

  • Links to MPA Garching, Arizona, Palermo, Torino


What is the flash code

What Is the FLASH Code?

  • Has a modern architecture

    modular with interfaces

    configurable with parameter/variable database

  • Is highly portable

    across software platforms: most UNICES including Linux

    across hardware platforms: MPI for intra- and inter-box communication

    scalar cache-based systems

    provides strong tests of software (operating system, compiler,

    language interoperability) and hardware (network, storage)

    parallel I/O with HDF5 for large data sets

  • Can solve a broad range of problems

    adaptive mesh discretization in 3-D with PARAMESH, compressible hydrodynamics,

    MHD, SRHD, elliptic operators, explicit diffusion, complex EOS, particle tracking

  • Future developments

    • extended framework through IBEAM (parallel solvers for large linear systems)

    • formal interface specification (for solvers and mesh component)

    • front tracking component

    • elements of TSTT/CCA forums

    • interoperability with other AMR software


Primary applications

Primary Applications

  • X-ray bursts on neutron star surfaces

  • Novae

  • Type Ia supernovae

Thecommon elements:

  • The underlying stars are compact

  • Members of close binary systems

  • Physical processes: hydrodynamics, complex EOS, gravitation, nuclear burning

  • Radiation hydrodynamics important at late times

  • Initial conditions involve long timescales (implicit solve)

  • Rapid evolution during final event (explicit solve)


Primary applications towards understanding

Primary Applications: Towards Understanding

  • What is environment for the explosion?

  • How does it form?

  • What happens during the explosion?

  • Where are complex elements produced?

  • How big is the Universe?

  • How old is the Universe?


Primary applications examples

Primary Applications: Examples

Flame-vortex interactions

Laser-driven shock instabilities

R-M instability

Wave breaking on white dwarfs

Cellular detonation

Helium burning on neutron stars

Magnetic and hydrodynamic Rayleigh-Taylor instabilities

Landau-Darrieus instability

Type Ia supernova


Primary applications examples1

Primary Applications: Examples

Wave breaking on white dwarfs

3-D Rayleigh-Taylor instability

Flame-vortexinteractions


Additional applications

Additional Applications

Jeans instability

Intracluster interactions

Non-relativistic accretion onto BH

Relativistic accretion onto NS


The flash 2 code at a glance

The FLASH 2+ Code: at a Glance

  • General description

    • parallel block-structured adaptive mesh refinement code

  • Solvers constantly developed

    • hyperbolic: hydrodynamics, MHD, and SRHD

    • elliptic: self-gravity

    • parabolic: thermal conduction

    • ODE: nuclear burning

  • Architecture undergoes substantial changes

    • modular, fine-grained, SPMD (patch-based), efficient parallelism

    • cache-based scalar architectures (most of the market)

    • mostly F90 with elements in C; no language restrictions

  • Testing one of the finest and most matured elements

    • used to control development and prevent major design flaws

    • compile  run  compare

    • applied daily on several platforms, centralized database


The flash 2 code physics modules

The FLASH 2+ Code: Physics Modules

  • Compressible hydro

    • PPM, WENO, Tadmore central-difference

    • MHD 2nd order TVD

    • SRHD 2nd order Godunov, Roe solver, R-K stepping

  • Source terms

    • Nuclear burning – variety of reaction networks

  • Gravitational field

    • Externally imposed

    • Self-gravity (multipole, multigrid, single level FFT)

  • Diffusion

    • Thermal

    • Conduction


The flash 2 code component model

mesh

The FLASH 2+ Code: Component Model

FLASH Component

  • 1. Meta-data (Configuration Info)

    • Variable/parameter registration

    • Variable attributes

    • Module requirements

    • Role in driver (?)

  • 2. Interface Wrapper

    • Exchange with variable database

  • 3. Physics Module(s)

    • Single patch, single proc functions

    • written in any language

    • Can be sub-classed

FLASH Application

driver

Collection of Flash Components

Database


The flash 2 code application builder

Source

Terms

Materials

Gravity

MHD

Driver

Hydro

Particles

I/O

Vis

The FLASH 2+ Code: Application Builder

Configuration

Tool

(Setup)

Database

Mesh


The flash 2 code application example

Sets solution variable

descriptions in database

Variable

Database

AMR Library

(PARAMESH)

Driver.f90

evolve(); timeStep();

Evolve.f90hydro3D( ); burn();

Data Flow

Class accessor methods

Global memory

Parameter list

Hydro3d.f90

computeRHS(arglist); eulerStep(arglist);

Burn.f90

burner(arglist);

PPM.f77

NetInt.f77

EulerStep.c

The FLASH 2+ Code: Application Example

Framework

Standard interfaces

Physics Modules

(easily interchanged)


The flash code

Mesh

Particles

Visualization

MHD

IO

Diffusion

Driver

Variable Database

init()

fill_guardcells()

test_refinement()

refine_derefine()

init()

advance()

init()

fill_guardcells()

test_refinement()

refine_derefine()

init()

render()

init()

write()

init()

dBaseGetData()

dBasePutData()

dBaseProperty()

init()

dBase_init()

dBaseGetData()

dBasePutData()

dBaseProperty()

Explicit

Implicit

constant

burn

Gamma

point_mass

iso13

Helmholtz

Unsplit

Split

Poisson

...

cool

heat

PPM

WENO

Multigrid

Multipole

Structure of FLASH

Modules

Hydro

Gravity

Source_terms

Materials

init()

tstep()

hydro3d()

init()

tstep()

grav3d()

init()

tstep()

src_terms()

eos3d()

eos1d()

eos()


The flash code

IO

Mesh

rk3

strang

steady

time dep

Driver

uniform

MPI

mesh

database

mesh

database

mesh

database

source terms

Hydro

burn

cool

heat

stir

explicit

implicit

aprox13

ppcno

delta form

split

unsplit

AMR

Gravity

paramesh

PPM

Kurganov

WENO

planpar

constant

poisson

PPM

MUSCL

MHD

2nd order

TVD

Materials

Particles

eos

composition

active

passive

HDF4.0

HDF5.0

f77_unf

hemlholtz

gamma

nadozhin

Runtime

Visualization

Solvers

PVTK

poisson

scripted

compiled

multigrid

multipole

The FLASH 2+ Code: Directory Structure


The flash 2 code additional features

The FLASH 2+ Code: Additional Features

  • External libraries

    • MPI for parallel execution

    • Paramesh for adaptive discretization

    • HDF5 for efficient I/O

    • pVTK for remote visualization

  • External tools

    • Python for configuration

    • gmake for code compilation

  • http://flash.uchicago.edu

    • Available with no major restrictions

    • Looking to expand user base

    • Support with short response time


Summary

Summary

  • FLASH aspires to become a community code

  • FLASH is freely available

  • Major emphases

    • Performance

    • Portability

    • Testing

    • Usability

    • Support (secured for at least next 5 years)

  • Interest, skill, and organization guarantees success

  • Future FLASH

    • Implicit hydro solvers; Front tracking mesh component

    • Solver and mesh interfaces

    • FLASH component model

    • FLASH developer’s guide


The flash code from design to applications

The FLASH Code: From Design to Applications

Questions and Discussion


The flash 2 code

The FLASH 2+ code


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