particlevis
A particle simulation visualization program
...Functionality includes data exploration, debugging of simulation output, and generation of presentation-quality imagery.
The ability to visualize vector flow information in a variety of forms, such as arrow-lines, inscribed glyphs, and motion blurred particles, is particularly useful in the study of granular flows. User-generated information can be integrated into the visualization using features such as per-particle color maps and surface maps, per-region vector fields, and volumetric data.