Objective: An Inviscid compressible hydrodynamic code based on Flux Corrected Transport (FCT) has been parallelized to run using different message passing libraries (NX, PVM & MPI) and several different problems. The objective has been to demonstrate this code for a meaningful physical problem.
Accomplishments: Three dimensional simulations of the Rayleigh-Taylor (RT) Instability have been performed on the 512 node Intel Paragon. Since the code is based on invisced hydrodynamics (Euler equations) the grid resolution chiefly determines the (numerical) viscosity and associated Reynolds number. Higher resolution runs hence can be thought of as representing higher Reynolds numbers and more likely to give rise to turbulent behavior. On the left is a run with resolution 64x64x256 showing the pattern foramtion in the density field that is observed in a view from the top at different heights. At the bottom is another composite view of another run with resolution 128x128x512. The left panel shows the density field in the vertical plane. The middle panel is the field orthogonal to the left view. The two cross-sectional views on the right are aligned such that their centerline is located at the corresponding height in the middle and left panels. Compare the panels on the left which appear laminar while the high resolution panels below show turbulence. The runs used 256 and 512 nodes respectively of the Caltech Intel Paragon. The code runs at just over 4 MFlops/node.
Significance: The 3D character of this instability has been
explored into the weakly turbulent regime for the first time using the
large scale simulation capability of parallel machines. The RT
instability is an important mixing mechanism in Inertial Confinement
Fusion and Supernovae (see B. Fryxell's work).
Status/Plans: The version of the code is being further optimized for the Cray T3D (and planned T3E). More runs are planned to explore parameter space.
References:
A. Deane, S. Zalesak & D. Spicer, "3D Compressible Hydrodynamics using
Flux Corrected Transport on Message Passing Parallel Computers," Proceedings of High Performance Computing '95, A. Tentner (Ed.) SCS (1995).
A. Deane, "Three-Dimensional Compressible Rayleigh-Taylor Instability
on the Intel Paragon," Intel Supercomputing Users Group Annual Meeting,
Knoxville, TN (1996).
A. Deane, "Parallel Computations of 3D Compressible Rayleigh-Taylor Instability," J. Comput. Math., (to appear).
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