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Isotropic, Homogeneous Driven Turbulence Simulation on LLNL BG/P

Isotropic, Homogeneous Driven Turbulence Simulation on LLNL BG/P. Don Q. Lamb SciDAC Conference Boston, MA 28 June 2007. (http://flash.uchicago.edu).

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Isotropic, Homogeneous Driven Turbulence Simulation on LLNL BG/P

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  1. Isotropic, Homogeneous Driven Turbulence Simulation on LLNL BG/P Don Q. Lamb SciDAC Conference Boston, MA 28 June 2007 (http://flash.uchicago.edu)

  2. Homogeneous, Isotropic, Driven Turbulence Simulation Using LLNL BG/L • 11 Million CPU hours (simulation ran on 65,536 processors for nearly a week of wall-clock time) • Very high resolution simulation using a high-order Godunov PPM integrator – 18563 grid points • Accurate Lagrangian sampling of inertial range – 2563 = 17 million tracer particles • Long-time steady-state evolution of a weakly compressible flow: > than a full eddy-turnover time • Wealth of high-quality data: Particle state stored at 1400 times, and grid statestored at 700 times

  3. Cut-Plane Visualization of Langrangian Tracer Particles

  4. FLASH Anomalous Scaling Exponents Compared Against Theory She-Leveque (1994) Kolmogorov (1962) First numerical simulation with sufficient numerical statistics to rule out theories of turbulence that include intermittency

  5. Synthetic Schlieren Map of Density Field

  6. Discovery: Scaling Properties of Density Are Different from Those of Scalar Field • Synthetic Schlieren map highlights regions of strong density gradients (in the plane of the image), which are yellow/white • Virtually all treatments of turbulent flow assume the flow is incompressible; the corresponding Schlieren map would be purely flat – in contrast to the wealth of structure we see • Furthermore, we have discovered that the scaling properties of the density are different from the expectation that they are similar to that of a passive scalar field – comparable images of a passive scalar field show significantly less structure on small scales • We were able to discover this because the homogeneous, isotropic, compressible simulation we ran on LLNL BG/L has a dynamic range far beyond that of any other compressible simulation

  7. Results of LLNL BG/L Turbulence Simulation • We have made a breakthrough in understanding and quantifying systematic statistical errors in higher-order structure functions – this is important for experiments as well as turbulent simulations • We have carried out the first turbulence simulation that is large enough to discriminate among models of turbulence that include intermittency • We have obtained new insights on fundamental properties of homogeneous, isotropic, compressible turbulence • We are making all 22.5 TB of data generated in simulation publicly available on mass storage device in Computation Institute at UofC for analysis by visitors and by turbulence scientists world-wide

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