1. An Advanced Simulation and Computation (ASC) Academic Strategic Alliances Program (ASAP) Center at The University of Chicago The Center for Astrophysical Thermonuclear Flashes Isotropic, Homogeneous Driven Turbulence Simulation on LLNL BG/P Don Q. Lamb SciDAC Conference Boston, MA 28 June 2007 (http://flash.uchicago.edu)

2. The ASC/Alliances Center for Astrophysical Thermonuclear Flashes The University of Chicago Homogeneous, Isotropic, Driven Turbulence Simulation Using LLNL BG/L q11 Million CPU hours (simulation ran on 65,536 processors for nearly a week of wall-clock time) qVery high resolution simulation using a high-order Godunov PPM integrator – 1856 3 grid points qAccurate Lagrangian sampling of inertial range – 256 3 = 17 million tracer particles qLong-time steady-state evolution of a weakly compressible flow: > than a full eddy-turnover time qWealth of high-quality data: Particle state stored at 1400 times, and grid state stored at 700 times

3. The ASC/Alliances Center for Astrophysical Thermonuclear Flashes The University of Chicago Cut-Plane Visualization of Langrangian Tracer Particles

4. The ASC/Alliances Center for Astrophysical Thermonuclear Flashes The University of Chicago FLASH Anomalous Scaling Exponents Compared Against Theory Kolmogorov (1962) She-Leveque (1994) First numerical simulation with sufficient numerical statistics to rule out theories of turbulence that include intermittency

5. The ASC/Alliances Center for Astrophysical Thermonuclear Flashes The University of Chicago Synthetic Schlieren Map of Density Field

6. The ASC/Alliances Center for Astrophysical Thermonuclear Flashes The University of Chicago Discovery: Scaling Properties of Density Are Different from Those of Scalar Field qSynthetic Schlieren map highlights regions of strong density gradients (in the plane of the image), which are yellow/white qVirtually 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 qFurthermore, 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 qWe 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. The ASC/Alliances Center for Astrophysical Thermonuclear Flashes The University of Chicago Results of LLNL BG/L Turbulence Simulation qWe 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 qWe have carried out the first turbulence simulation that is large enough to discriminate among models of turbulence that include intermittency qWe have obtained new insights on fundamental properties of homogeneous, isotropic, compressible turbulence qWe 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