SPARTA Direct Simulation Monte Carlo (DSMC) Simulator

The generation of random numbers is too important to be left to chance. -- Robert Coveyou
God does not play dice. -- Albert Einstein

This is the home page for the DSMC code SPARTA, an acronym for Stochastic PArallel Rarefied-gas Time-accurate Analyzer.

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SPARTA is a parallel DSMC code for performing simulations of low-density gases in 2d or 3d. Particles advect through a hierarchical Cartesian grid that overlays the simulation box. The grid is used to group particles by grid cell for purposes of performing collisions and chemistry. Physical objects with triangulated surfaces can be embedded in the grid, creating cut and split grid cells. The grid is also used to efficiently find particle/surface collisions.

SPARTA runs on single processors or in parallel using message-passing techniques and a spatial-decomposition of the simulation domain. The code is designed to be easy to modify or extend with new functionality.

SPARTA is distributed as an open source code under the terms of the GPL, or sometimes (by request) under the terms of the GNU Lesser General Public License (LGPL). The current version can be downloaded here.

SPARTA was developed at Sandia National Laboratories, a US Department of Energy (DOE) laboratory. The chief authors are Steve Plimpton and Michael Gallis who can be contacted at sjplimp at and magalli at respectively. Funding for SPARTA development has come from the DOE.

The SPARTA web site is hosted by Sandia National Laboratories, which has this Privacy and Security statement.

Recent SPARTA News

SPARTA Highlight

(see the Pictures & Movies page for more examples of SPARTA calculations)

This is work by Michael Gallis (magalli at at Sandia.

This calculation was done to model Richtmyer/Meshkov mixing which occurs when a light gas is on top of a heavier gas and a shock induces mixing and turbulent effects.

This is a large 2d calculation of He (green) on top of Ar (red). 4.5B particles were run with 400M grid cells for 240K timesteps. The simulation was run on 32K nodes (16 cores per node, 512K MPI tasks) of the Sequoia BG/Q machine at Lawrence Livermore National Labs (LLNL).

Snapshot images of the simulation were created using SPARTA's dump image command, rather than saving particle data to disk. The first 2 images are the initial and final state of the simulation. The rightmost image is a movie of the simulation.

2 images and a 0.5 Mb QuickTime movie

This paper has further details about the mixing model:

Direct Simulation Monte Carlo: The Quest for Speed, M. A. Gallis, J. R. Torczynski, S. J. Plimpton, D. J. Rader, and T. Koehler, Proceedings of the 29th Rarefied Gas Dynamics (RGD) Symposium, Xi'an, China, July 2014. (to be published by AIP) (abstract)