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Foundation ::
Engineering Applications ::
SAGE
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SAGE
Multi-Dimensional Self-Adaptive Grid Code
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SOURCE CODE AVAILABLE
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The Multi-Dimensional Self-Adaptive Grid Code, SAGE, provides an efficient method to improve the accuracy of CFD flow solutions while simultaneously reducing computer processing time. SAGE enhances an initial computational grid by redistributing the mesh points into more appropriate locations. The movement of these points is driven by an equal-error distribution algorithm that utilizes the relationship between high flow gradient and excessive solution errors. The method also provides a balance between clustering points in the high gradient regions and maintaining the smoothness and continuity of the adapted grid. The SAGE code can improve the efficiency of CFD flow field solvers in four ways:
- by creating a grid that improves the accuracy of the solution by distributing computational error evenly throughout the solution domain,
- by speeding up the convergence of the flow solver,
- by enabling a non-convergent application to converge, and
- by reducing the time and effort to produce the initial grid: the ability to adapt during the solution process removes the requirement to create a "best-possible" first grid.
The user provides a grid file and an associated interim flow solution file. It is assumed that the files are in PLOT3D binary format, but the user may change the read statements to conform to another format. The grid must be structured but may be 2-D or 3-D, finite difference or finite volume, single or multiple. The user also provides a set of parameters to control the adaption. These include maximum and minimum grid spacings, boundary matching, and adaption direction. All parameters have default values and the user-guide contains details and examples of varying these defaults. Two files are output from the SAGE code: the adapted grid and the flow solution interpolated onto the new grid points. These files are immediately usable for re-input to the flow solver.
SAGE carries the NASA case number ARC-13359. It was originally released as part of the NASA COSMIC collection.
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