There have been several improvements to unstructured meshing in CFD-GEOM V2007. These new capabilities add more flexibility to unstructured meshing in CFD-GEOM as well as an overall better user experience.

The biggest change in V2007 is how surface meshes are stored. In V2006, surface meshes were stored on loops and not the surface itself, which limited the ability for local mesh refinement. In V2007, surface meshes are stored on each surface, therefore allowing for local meshing parameter specification. This fundamental change allows for more surface meshing options and local mesh refinement.

Curve meshing is now allowed, which greatly improves the ability to control mesh size. Surface meshes are generated from the curves bounding the surface, which means that curve meshing will give a very good indication of the final density of the surface mesh. This means that the surface mesh density can be "previewed" by meshing the curves, and therefore circumventing the need to mesh the surface to see the density/quality (surface meshing is much more computationally expensive than curve meshing).

Meshing parameters for curves may be set locally or globally. The local option (Set Local) is essential to control mesh size in different parts of the geometry, i.e. allowing for a coarse mesh in non-important regions and a fine mesh in critical regions.

The different surface mesh types, triangular, quad-paving, and quad-morphing, have been combined into one tool. The mesh type can be specified at the top of the surface meshing tool by selecting the desired option.

Similar to Curve Meshing, cell sizes can now be specified surface by surface (Set Local option), or a global cell size may be specified (Set Global).

• Set Local - Will set the current cell size settings for the currently selected surfaces.
• Set Global - This option will set the current cell size settings for the entire model, except where local settings have been set using the Set Local option.
• Unset Local - This will remove local settings on the surface, and global settings will then be used.

The Grid Only Ungrid option is removed in V2007, but has been replaced with other options that allow more control over meshing.

• Remesh Curves - To remesh a surface that already has mesh, select this option. This will remesh all the bounding curves for the surface and generate a new surface mesh. If the surface shares a line/curve with another surface, that curve will not be remeshed (see the next option).
• Force Line/Curve Remeshing - This will force remeshing of all the lines/curves of the surface, including lines/curves that are shared with other surfaces that may already have a surface mesh. The preexisting surface mesh for surfaces that share lines/curves will be destroyed unless both surfaces are chosen.
• Force Surface Remeshing - This option allows you to remesh all surfaces in the model. There could be meshed surfaces and unmeshed surfaces in the model at any given time. If all surfaces are selected, then this option needs to be checked, else only unmeshed surfaces will be meshed.
• Override Local Settings - This will override any locally defined meshing parameters with the current mesh settings.

When you upgrade to CFD-GEOM V2007, try these new features when you need an unstructured mesh.

If you have any questions about this tip or would like us to discuss some other topic in the future, please let us know.

Regards,
William Kuykendall
Applications Engineer