This image depicts one timestep in the simulation of a rarefied flowfield emanating from a pair of reaction-control jets being fired in a vacuum. The accompanying MPEG animation shows the progress of the simulation over the first 200 timesteps. Results from this and similar simulations will be used to help characterize the loads on space structures due to plume impingement from nearby vehicles.
The animation was produced by adding PGL calls to a parallel Direct Simulation Monte Carlo (DSMC) code developed by Dick Wilmoth at NASA's Langley Research Center. The simulation was run on Langley's Intel Paragon using 32 processors. Each particle in the animation represents a single "molecule" from the simulation. Molecules are color-coded by velocity magnitude, with white and magenta being the fastest, and blue and green being the slowest. Yellow, orange, and red colors represent intermediate velocities.
The ymftoppm utility was used to extract the image from the YMF output file produced by PGL. The PPM image was then resized and converted to GIF format with John Bradley's xv program. Finally, the MPEG icon was added to the GIF image using John Cristy's ImageMagick package.
To produce the MPEG animation, we re-rendered the simulation at 352 x 240 resolution using PGL, and converted the YMF file to MPEG with the ymftompeg utility.
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