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Gridgen Version 13.2 - 01 Jul 1998

Gridgen Version 13.2 features great leaps in technology in terms of unstructured grids, grid quality diagnostics, and interoperability with FIELDVIEW.

Unstructured Grids

Gridgen Version 13.2 introduces unstructured domains (triangles) and unstructured blocks (tetrahedra) to Gridgen's data hierarchy. They've been implemented in a manner very similar to their structured grid counterparts. Unstructured domains are created by selecting the closed loop of connectors on the domain's perimeter. Of course, there is only one edge on the perimeter of an unstructured domain and you may use as many points as you wish.

The initial triangular grid is created using the same rules as for the structured grids (i.e., Parametric and Parametric Fit TFI); if possible, Gridgen will create the grid to adhere to the underlying database. You may then re-apply the triangular solver to obtain a grid that meets your specifications for minimum and maximum cell size, maximum deviation from the underlying database, smoothness, and clustering.

The tetrahedral solver works in much the same manner except that it's a true Delaunay method (i.e., no smoothing). The concept of multi-block grids has been retained for unstructured grids. You may even mix and match structured and unstructured grids in the same grid system if your flow solver permits it.


Gridgen's Examine command has been totally re-written to allow you to compute and display grid quality measures for any or all of the connectors, domains, and blocks in your grid system. You can check for adherance to the database, cell size, cell size variation, Jacobians, cell aspect ratio, and cell skewness.

The Display window will show a color contoured, graphical representation of the chosen diagnostic measure in wireframe, solid, or solid and wireframe display styles. A histogram is available for visualizing the distribution of cell types. And, you may set your own criteria for each of the diagnostic measures and have Gridgen only display the "bad" cells, those that exceed your criteria.


Several new features have been added to improve Gridgen's ability to work with FIELDVIEW, should you be using that software for your CFD results visualization. You can now import and export volume grids in the FIELDVIEW Unstructured (FV-UNS) format. And you may also export a FIELDVIEW Structured Boundary File for your structured grid.

There are also a wide variety of smaller enhancements contained in Gridgen Version 13.2 that will make your job a lot easier. These improvements include:

Block Splitting and Joining
You may now split and join structured blocks.
Fortran Unformatted
Fortran unformatted format is now supported for PLOT3D file import and export for surface and volume grids and database networks.
IGES Bounded Surfaces
Gridgen now imports the complete trimmed surface information from IGES Bounded Surface (143) and Boundary (141) entities.
More Analysis Software
Support has been added for Cobalt, FDNS, GUST, INCA v3, SCRYU, and WIND. Of course, all existing analysis software filters have been enhanced to support unstructured grids (where allowed).
Average Delta-S Default
This new entry in the Defaults menu lets you specify a spacing constraint to be applied to all new connectors so that grids points are equally spaced at the value you specify. The dimension of the connector is then determined implicitly. This works great when creating unstructured grids.
Normal to Database Movement Restriction
When using the 3D cursor to create connectors you can now restrict cursor's movement to the direction normal to the database, defined at the previous control point's location (which, of course, has to have been placed on the database).
Add Control Points by Entering an Offset, Linear Projection, and Closest Point Projection
Three new options are available to you when using the 3D cursor to define control points. You may enter an offset from the previous point's location, you may cast a ray in the screen-z direction onto the database, or you may simply closest point project the 3D cursor onto the database.
Segment File CleanUp
Gridgen now automatically removes consecutive, coincident points from segment files on import.
Enhanced Domain and Block Picking
When picking domains and blocks, Gridgen now highlights and allows you to pick from the first layer of grid cells. This reduces the number of times you'll have to use the x hot key to pick the item you want.
You can now create subblocks and use them in the algebraic and elliptic solvers.
Surface grids may now be imported and exported via VRML and STL formats.
Elliptic PDE Attributes in GCL
The GCL has been expanded to allow you to specify a more complete set of elliptic PDE attributes.
Small Text
You can now increase the size of the Display Window by using a small (8 point) font for the menu bar text.

As first mentioned in the Release Notes for Gridgen Version 12.1.3, Gridgen Version 13's support for Hewlett-Packard workstations has been changed to only workstations running HP-UX 10.20.

Please note that Gridgen Version 13.2 requires a complete re-install from the CD-ROM as several features have changed, including the Tutorials and the License Manager. New Keys will be required. Please consult the Installation instructions for more details.