Although most of the meshing modules within Ansys ICEM CFD allow minor gaps and holes in the geometry, you should confirm that the geometry is free of any flaws that would inhibit optimal mesh creation. For example, the tetra mesher requires that the model contains a closed volume; if there are any holes in the geometry that are larger than the local tetras, the mesh will not be created. Ansys ICEM CFD provides tools for such operations on either CAD or triangulated surfaces.

The Repair Geometry page in the Help manual provides links to the tools that are used to find and repair such flaws. The typical procedure is to identify possible geometry problems using the Build Topology operation and then use the other tools to effect any needed repair.

In cases where feature capture is necessary, geometry curves and points will act as constraints for the edges and nodes, respectively, of the mesh elements. If necessary, Build Topology is able to create such curves and points automatically from surface data, thereby capturing certain key features in the geometry.

See Repairing the Geometry before Meshing in the Tetra Meshing chapter for more information on geometry preparation.