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Gridgen Now Integrated with Overset Grid Assembly

The addition of overset grid assembly (OGA) capability to Gridgen represents a substantial leap in functionality for the version 15.16 release. The overset feature suite provides the ability to set OGA parameters, launch the assembly software, and import and visualize the assembly results. By closely coupling mesh generation and OGA, you have the ability to immediately adjust your grid when the OGA software (also known as the hole cutter) creates orphan points or poor interpolation stencils.

Setup and Launch Overset Assembly

Generating an overset structured grid begins with the generation of individual, overlapping component grid blocks. Using the new Overset Attributes in Gridgen's custom boundary condition command, you set body, grid, and boundary names for your grids. Selection of the hole cutting software, case names, and global and custom attributes is performed with a new Overset Settings command. Gridgen currently supports PEGASUS5 (from NASA) and SUGGAR (from Penn State). For PEGASUS5, all component grids are written to the X_DIR directory, O- and C-grid connections are automatically determined, and a PEG.in namelist control file is written. For SUGGAR, the component grids are all written to the Grids directory, connections including O-grids are automatically determined, and master and per-block XML files are written to the Input directory. From within Gridgen, you then launch the OGA software which runs as a child process.

Let Overset Assembly Results Guide Your Gridding

When the OGA software finishes, you import the results including IBLANK data from PLOT3D files. The IBLANK data includes the classification of points as fringe, hole, or orphan. Once that data is imported, several new display tools are available to you in Gridgen. On a block by block basis you can turn on the display of fringe, hole, and orphan points so they can be used as a guide for grid editing. The Examine command provides even finer control over point display and excludes hole points on cutting planes. Examine also supports IBLANK as a scalar function to provide a color-mapped view of the OGA, making it easier to find orphans and other undesirable features.