Objective: A three-dimensional Eulerian hydrodynamics code has been developed that is based on the technique of Flux Corrected Transport with the limiting done on characteristic variables. The resulting scheme is storage intensive and a restructuring of the algorithm has been performed to produce a code that requires of the order of 15 (and under some circumstances, 10) 3D field arrays. Test results for the double-shock tube and that of a Mach 10 impingement on a 30 degree ramp problems are very encouraging showing that the code is robust and can handle strong shocks. The objective was to then apply this code to the complex flow that arrises in 3D compressible turbulence.
Accomplishments: Computations of 3D fully compressible
homogeneous isotropic turbulence have been performed on the Convex
SPP-1000 parallel computer. Initial random Gaussian velocity fields
are allowed to evolve to produce intermediate time intense
fluctuations and final relaxation to Kolmogorov-like inertial
dynamics. Runs of resolution 128x128x128 show these initial conditions
evolve in 3 phases: a ramp up, strong fluctuations, and a quiescent
slow decay. The figure on the right shows the enstrophy field (square
of the vorticity) at these three stages of evolution. At the earliest time high vorticity is associated with sheet like structures whick then
become tube-like at later times. The figure on the left shows the
speedup obtained with the code on the SPP-1000 using compiler
directive parallelization.
Significance: Such behavior is similar to that found by Porter, Poquet & Woodward who have computed cases with this and with much higher resolution but using a different technique (PPM).
Status/Plans: Higher resolution runs are planned as is the parallelization for the Cray T3D.
Point of Contact:
Dr. Anil Deane
High Perfornamce Computing Branch
NASA Goddard Space Flight Center &
Institute for Computational Science and Informatics
George Mason University
deane@laplace.gsfc.nasa.gov