Progress on FLASH Target Application Simulationsflash.uchicago.edu/~dubey/Feb28_2011/Milad_simulations.pdf · codesign-kickof-simulations.ppt Author: Anshu Dubey Created Date: 2/27/2011

Flash Center for Computational Science University of Chicago

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ANL February 2011

Milad Fatenejad DOE NNSA ASCR Flash Center

University of Chicago

Progress on FLASH Target Application Simulations

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Flash Center for Computational Science The University of Chicago

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Table of Contents

 Reasons for choosing the CRASH experiment as the target application

 Progress on FLASH HEDP development  Progress in understanding physics/data

requirements through a new collaboration

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The CRASH experiment was chosen as the first target application for several compelling reasons

  Experiments have already been performed and data is available

  The key validation features (shock position, structure) are robust and reproducible

  It is possible to perform NIF experiments using this setup for further validation

  Experiments exercise most of the basic capabilities needed for HEDP simulations

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Data is available from CRASH experiments which have features that have proven to be extremely robust

  Radiographs from many CRASH experiments show a planar shock wave

  Images from different times show that the shock persists for a long time

26 ns 14 ns

F. Doss, et al., HEDP 6, 157 (2010) Drake, et al., Conf. Proc. RPDHM2010, HEDP, submitted

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CRASH experiment simulations require modeling several types of important HEDP physics

  The following physics is required to model the target application:   2T Ion/electron hydrodynamics with radiation transport

  Thermal conduction

  Laser energy deposition

  Multiple materials (Be, Xe, Au, polyimide, acrylic)

  EOS and opacities for these materials

  Once these capabilities are implemented and the target application is satisfactorily simulated, sophisticated, inline, non-LTE opacity and EOS models will be implemented and tested

  These capabilities combined with Exascale computing power will enable transformative HEDP simulations and science

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New physics and numerical methods are needed in FLASH to simulate the target application

  1-T Hydrodynamics must be extended to support separate ion/electron temperatures with radiation transport   Properly controlling the differential heating of ions/electrons near a

shock is an unsolved problem for Godunov style Eulerian fluids codes

  Several hydrodynamic models are being incorporated into FLASH to determine the best approach

  An implicit diffusion solver is necessary for modeling thermal conduction and radiative transfer with flux-limited multigroup diffusion (FLMGD)   We plan to support several external libraries, including HYPRE and

PETSc

  We are using HYPRE in implicit diffusion solvers for uniform grids and plan to use it for AMR

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New physics and numerical methods are needed in FLASH to simulate the target application

  Laser ray-tracing is needed to drive the simulation   Rapid progress has been made in this area because of the block-

structured mesh in FLASH and by leveraging the pre-existing particles capability

  Opacities are needed for the multigroup diffusion calculation   Preliminary work has focused on supporting tabulated opacities

  Future work will focus on implementing sophisticated in-line non-LTE models; this approach will greatly benefit from Exascale capabilities

  Sophisticated multi-material equation of state (EOS) models are needed in many HEDP simulations   The multi-material infrastructure is undergoing development with

preliminary work focusing on tabulated equations of state

  Future work targeting in-line EOS calculations will also benefit from Exascale capabilities.

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Implementation of HEDP capabilities is progressing rapidly

FLASH Capability Future Development

Ongoing Development

Completed and Under Testing

RAGE Hydro X

CRASH Hydro X

Entropy Advection X

HYPRE Diffusion X

Multigroup Radiation Diffusion X

Electron Conduction X

Laser Ray-Tracing X

Tabulated Multimaterial EOS X

Opacity X

Inline non-LTE Opacity X

Inline EOS X

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Verification with analytic solutions and code-to-code comparisons are continuously performed

Comparison of 2T shock structure between analytic Shafranov1 solution, a Lagrangian code solution, and FLASH – entropy advection show excellent agreement.

Comparison of 2T shock structure between FLASH using RAGE-Like hydro and the RAGE code itself show reasonable agreement. Further investigation is ongoing.

1V.D. Shafranov, Soviet Physics JETP 5, 1183 (1957)

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A new collaboration with labs/universities has led to further understanding the simulation requirements

  Collaboration with national laboratories and universities is necessary for successfully simulating the target application

  National laboratories: LLNL and LANL   The national laboratories have extensive knowledge and experience in

running HEDP simulations   They have provided useful data which has helped identify where better

treatments of the physics are needed (e.g. EOS and opacities)

  FLASH/RAGE code-to-code comparisons are helping to improve both codes

  Universities: FLASH Center, CRASH, University of Wisconsin-Madison   The CRASH center has provided essential experimental/simulation data   Code-to-code comparisons with the CRASH code are ongoing   UW is helping develop the FLASH Center’s EOS/opacity capability

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The collaboration has already led to a deeper understanding of the physics/data needed to model the experiment

  Previous HYDRA simulations1 performed by CRASH demonstrated that flux-limited multigroup diffusion (FLMGD) is sufficient for obtaining agreement with the experiment

  Recent RAGE simulations have shown little qualitative difference between FLMGD and IMC

  Consultation with LLNL has provided strong evidence that the EOS/opacity can be accurately described using an LTE model

1F. Doss, et al., HEDP 6, 157 (2010) 11


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Comparison with sophisticated LANL polyimide opacity has shown reasonable agreement

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Analysis of LANL data has shown that bound-bound transitions dominate in the critical frequency range

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Analysis of LANL data has shown that bound-bound transitions dominate in the critical frequency range

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Current university opacity models are unable to accurately model the bound-bound behavior

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The collaboration will continue to answer critical questions and improve the fidelity of the simulations

  How sensitive is the solution to the Xenon and Polyimide opacity?   How does the underlying hydrodynamic model (ALE vs. Eulerian)

affect the solution?   Is laser ray-tracing necessary to model the experiment or can X-

ray drive suffice?   How sensitive is the solution to zoning, refinement, and spatial

resolution   Code-to-code comparisons with FLASH / RAGE / CRASH will

continue to improve all three codes

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Progress on FLASH Target Application Simulationsflash.uchicago.edu/~dubey/Feb28_2011/Milad_simulations.pdf · codesign-kickof-simulations.ppt Author: Anshu Dubey Created Date: 2/27/2011

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