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Info about the parallel coupled multiphysics simulation application

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Rocstar is a multiphysics simulation application designed to do fluid-structure interaction (FSI) across moving, reacting interfaces. Rocstar couples multiple domain-specific simulation packages and disparately discretized domains and provides several simulation-supporting services including conservative and accurate data transfer, surface propagation, and parallel I/O. Rocstar is MPI parallel and routinely executes large simulations on massively parallel platforms. Rocstar was originally developed at the University of Illinois Center for Simulation of Advanced Rockets (CSAR) under Department of Energy ASCI funding. Ongoing development of Rocstar is conducted by Illinois Rocstar LLC development team with company IR&D and continued DOE SBIR funding.

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(Left) Space Shuttle Reusable Solid Rocket Motor (RSRM) 0.7 s after ignition showing temperature contours within star grain and down center bore. (Right) Simulation of BATES motor nozzle visualizing aluminum and aluminum oxide particulates passing into and through nozzle.

The Rocstar simulation application was developed and successfully deployed over the lifetime of the Illinois DOE ASCI Center for Simulation of Advanced Rockets (CSAR) as a predictive simulation tool for solid rocket motor (SRM) internal ballistics and performance. It is recognized in the SRM industry as one of the world’s only fully three-dimensional, time-accurate SRM simulators. Rocstar is MPI parallel and has demonstrated scalability to tens of thousands of cores on many of the world’s largest HPC platforms. Since the time of CSAR, Rocstar has been utilized in many academic, government, and industry settings to conduct predictive simulations of general fluid--structure systems that interact across moving and reacting interfaces.

As illustrated in the diagram above, Rocstar orchestrates multiple software and simulation components in concert to simulate multiphysics systems. Rocstar’s individual component codes are based on fundamental research and development in turbulence modeling, multiphase flow, constitutive modeling, combustion chemistry, computational mechanics, coupling methodology, etc. Through collaborations with Illinois Rocstar LLC, Rocstar is increasingly relied upon by academic, industry, and government researchers for multiphysics simulation and has provided significant capabilities to the SRM programs of DoD, NASA, and the U.S. rocket industry. Recent examples of Rocstar use include internal acoustics analyses of a proposed five-segment Constellation heavy-lift launch SRM for NASA, characterizations of the distribution of aluminum impingement on rocket nozzles for the USAF, and multiscale modeling of solid propellants for ATK Inc.

Although the original target for Rocstar was internal ballistics of SRM, Rocstar is capable of simulating a wide variety of multicomponent systems involving fluid dynamics, structural dynamics, combustion, and their interactions. Rocstar features multiple state-of-the-art solvers for various types of physical components. Rocstar has been applied to several fluid--structure interaction and multiphase flow problems in addition to rocketry, including simulations of heated plumes in a cross-wind (e.g., Naval surface ship smokestacks), noise from helicopter blades, fuel injectors, volcanoes, and the effects of wind on tall buildings.

(Left) Joint slot area in the space shuttle reusable solid rocket motor (RSRM) at late burn time showing turbulent flow past a protruding inhibitor flap. Dynamic Smagorinsky LES turbulence model used with total vorticity shown. (Right) Space Shuttle Booster Separation Motor milliseconds after ignition showing swirl in nozzle inlet area due to canted nozzle.

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