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Multiphysics Simulations Supersonic nozzle flow against a flat plate, showing density (grey) and vorticity (colors). Read More >

Rocstar Simulation Cutaway of a joint slot in the Space Shuttle solid motor showing inhibitor fluid-structure interaction. Read More >


Rocpack is a serial simulation tool designed to produce random close-packings of polydisperse convex shapes. The packs generated by it are useful in modeling random, heterogenous materials such as propellants, explosives, aggregates, and other granular materials. The algorithm used in Rocpack is a variant of the original Lubachevsky–Stillinger (LS) algorithm.  Level sets are used to represent and evolve the inter-particle distances for collision detection, and modern Event-Driven Molecular Dynamics techniques are used for optimization.

There are two versions of Rocpack; one packs only spheres and is optimized for computational speed. The other version packs a set of arbitrary shapes. Rocpack can pack arbitrary collections and mixtures of the currently implemented shapes with polydisperse sizes into any of the implemented domain shapes with periodic or hard-walled boundaries. The currently implemented particle shapes consist of sphere, gelcap, cylinder, icosahedron, cube, HMX, HMX2, PETN, RDX, ADN, and CL20. The currently implemented domain shapes consists of cuboid, cylinder, and annulus. Discrete particle size distributions can be used for each particle shape.Images of example packs are shown below.

Rocpack is distributed as executable files on Linux (as an .rpm archive) or in a newly available Microsoft Windows distribution. Contact sales@illinoisrocstar.com for information on licensing Rocpack.