isotropic, homogeneous driven turbulence simulation on llnl bg/p
DESCRIPTION
Isotropic, Homogeneous Driven Turbulence Simulation on LLNL BG/P. Don Q. Lamb SciDAC Conference Boston, MA 28 June 2007. (http://flash.uchicago.edu). - PowerPoint PPT PresentationTRANSCRIPT
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)
The ASC/Alliances Center for Astrophysical Thermonuclear FlashesThe University of Chicago
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 state stored at 700 times
The ASC/Alliances Center for Astrophysical Thermonuclear FlashesThe University of Chicago
Cut-Plane Visualization of Langrangian Tracer Particles
The ASC/Alliances Center for Astrophysical Thermonuclear FlashesThe 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
The ASC/Alliances Center for Astrophysical Thermonuclear FlashesThe University of Chicago
Synthetic Schlieren Map of Density Field
The ASC/Alliances Center for Astrophysical Thermonuclear FlashesThe University of Chicago
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
The ASC/Alliances Center for Astrophysical Thermonuclear FlashesThe University of Chicago
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