PEGASUS 5: An Automated Pre-Processor for Overset-Grid CFD

Suhs, Norman E.; Rogers, Stuart E.; Dietz, William E.

doi:10.2514/6.2002-3186

Cited by 113 publications

(40 citation statements)

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“…a dynamic overset approach). Hole cutting and connectivity information between overlapping blocks is created in a pre-processing step by Pegasus 5.1: an automated pre-processor code for overset grids, originally developed at NASA Ames Research Center for aerospace applications [20]. The double fringe layer Pegasus software option is used to allow the flow solver to retain the same higher-order five-point 1D stencil at near hole and near outer boundary points.…”

Section: Overset Gridsmentioning

confidence: 99%

Simulation of ship breaking bow waves and induced vortices and scars

Wilson

Carrica

Stern

2006

Numerical Methods in Fluids

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SUMMARYAn unsteady single-phase level set RANS method is used to resolve and investigate bow wave breaking around a surface combatant advancing in calm water, including induced vortices and free surface scars. A level set free surface capturing approach was extended and combined with local overset grid refinement for resolution of complex interfacial topologies and small-scale free surface features. Although the focus of the paper is on wave breaking at Fr = 0.35, results over three speeds (Fr = 0.28, 0.35, and 0.41) show that the method can accurately predict the changes in resistance and free surface topology, with the two highest speeds showing bow wave breaking. For the Fr = 0.35 case, comparison of wave elevation results shows good agreement with the data, including the development and thickening of the bow wave sheet, sequential formation of two overturning plungers with reconnections, and the formation of two free surface scars at the reconnection sites. The computational fluid dynamics (CFD) solution shows a steep shoulder wave, similar to the experiment, but does not predict the experimentally observed weak spilling breaking shoulder wave. Although the current predictions converge to steady state, the region of unsteady free surface measured experimentally can be reasonably well predicted from the region of the simulation where the wave slope exceeds 17 • . Comparisons of velocity components and axial vorticity at four cross planes show that the method can accurately predict the wake of low axial velocity and vortical cross flow associated with the breaking bow wave. In addition, the simulation is used to explain the initial development of the overturning bow wave, induced vortices and scars and to fill in the relatively sparse experimental data set by providing a global picture of the axial vortex structure near the free surface.

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Section: Overset Gridsmentioning

confidence: 99%

Simulation of ship breaking bow waves and induced vortices and scars

Wilson

Carrica

Stern

2006

Numerical Methods in Fluids

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“…The overlap optimization function aims at removing some points in overlapping regions in order to minimize the remaining overlap. The algorithm is based on the one developed in [39]. In Connector module, it is further split into two functions:…”

Section: Connector Modulementioning

confidence: 99%

Cassiopee: A CFD pre- and post-processing tool

Benoît

Péron

Landier

2015

Aerospace Science and Technology

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This paper presents an overview of the capabilities of a new open-source pre-and post-processing tool for Computational Fluid Dynamics simulations, called Cassiopee. Its architecture, which is basically a set of Python modules, and the handled data, which is based on CGNS standard, are described. Some examples of workflows that can be built with Cassiopee functions are provided. Finally, some applications of Cassiopee functions to realistic CFD configurations are briefly presented.

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“…There are a variety of ways to do this [55], but here this task is performed using the PEGASUS Version 5 software package. [56] In addition to the grids themselves and the input necessary to guide the operation of the code, PEGASUS requires specification of the boundary conditions that will be enforced in the solution domain by the flow solver. Typically, it is assumed that any grid boundaries that do not have boundary conditions specified by the input data will require interpolation.…”

Section: Preprocessing Elementsmentioning

confidence: 99%