Pegasus software is used as a pre-processor for overset-grid Computational Fluid Dynamics (CFD) simulations. It provides the hole-cutting and connectivity information between structured overset grids. The main features of the software include automated hole-cutting algorithms, a projection scheme for fixing small discretization errors in overset surface, efficient interpolation search methods, hole-size optimization based on adding additional layers of fringe points, and an automatic restart capability. The code can run in parallel using the Message-Passing Interface (MPI) standard.

The parallel performance provides efficient speed-up of the execution time utilizing dozens or even hundreds of processors. The new 5.2 release is a software upgrade to the existing Pegasus version 5.1. The additional capabilities in the new version include support for cell-centered grids, triple-fringe option, automated domain decomposition into multiple hole-cutters, improved parallel execution load-balancing algorithm, and additional minor enhancements.

The new version was developed to provide the ability to pre-process overset grids, which could be used by cell-centered-based CFD flow solvers, such as the DPLR CFD flow solver.

The Pegasus software is typically used as a pre-processor for CFD analysis of an aerospace vehicle. The Pegasus software provides data that gives the CFD solver a description of the geometry of the vehicle. The end result of the CFD analysis is an engineering assessment of the aerodynamic performance of the vehicle. The aerodynamic performance data obtained from such simulations are typically used together with other sources of aerodynamic performance estimates, such as wind-tunnel data, flight-test data, and/or other analytical analysis. It is expected that any safety-critical functions that rely on the accuracy of the aerodynamic performance data for any vehicle will be validated through multiple sources. Therefore, any fault in the Pegasus software should not result in any safety-critical consequences.

This work was done by Stuart Rogers of Ames Research Center. This software is available for use. To request a copy, please visit here .

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This article first appeared in the October, 2017 issue of Tech Briefs Magazine.

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