By Erling Eklund, GAMBIT Product Market Manager

GAMBIT 2.1, planned for an early 2003 release, addresses many needs that have been voiced by Fluent software users. Chief among these was a need to make geometry import and cleanup from CAD packages easier.

Several new features have been added to GAMBIT to help streamline CAD import. The IGES, STEP, and Parasolid CAD translators have been upgraded, and direct integration with Pro/ENGINEER ® has been enhanced. A new, native CATIA V4 translator add-on* is now available, offering much-improved results for CATIA V4 users. Furthermore, GAMBIT 2.1 can automatically adjust to imported CAD tolerances, enabling use of the full suite of Volume Boolean operations (Unite, Subtract, Split) on most imported geometries.

The cleanup of imported geometries is now made much easier than before, with a set of automated and semi-automated tools. Tasks that were previously time-consuming can now be performed tools allow the user to easily patch holes and close cracks in the geometry, eliminate short edges and sharp face angles that can cause bad mesh quality, and remove unwanted geometric features that are not needed for the CFD simulation. The Guided Cleanup capability offers a semi-automatic tool that identifies, zooms-in, and highlights areas that can cause connectivity and mesh quality problems. For each problem area, a choice of repair techniques is presented to the user, who can accept the default choice or select another method. (See the Support Corner article on the next page for more information on this functionality.) Several other tools are also available to improve imported geometries. These can be used to crop sharp angles, split surfaces and volumes with a few mouse clicks, and intersect surfaces of all types.

GAMBIT 2.0.4, released in February of this year, introduced a new level of meshing automation with the introduction of Size Functions, time-saving tools from small to large elements. In GAMBIT 2.1, the Size Function capability has been improved, delivering faster and more-accurate mesh generation. The Cartesian Stair-step meshing algorithm has become more efficient, offering improved speed while requiring less memory. This capability has been merged with the hybrid meshing routines to allow a new type of “HexCore” mesh, which features a tet/hybrid mesh adjacent to walls and a Cartesian mesh in core flow regions. HexCore meshes combine the automation and geometric flexibility of tet/hybrid meshes with greatly reduced cell counts in many applications.

Finally, application-specific templates, developed by Fluent consultants, can be created that offer customized GUIs to facilitate geometry and mesh generation for single applications, such as cyclone separators, packed beds, and coal-fired furnaces. Contact your technical support engineer if this option is of interest to you.

Inside the red box: The imported geometry has one extremely short edge (edge.173) and several sharp corners; these problems are automatically found and fixed by the new cleanup tools
An IGES surface geometry of a PVC window profile extrusion die; GAMBIT creates an ACIS solid upon import using the new tolerant modeling option; Boolean operations are then used to decompose the imported geometry into four volumes

An example of a HexCore mesh, used in combination with tet and Coopered mesh topologies
Figures courtesy of Kömmerling Kunststoff GmbH

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