When the imported surface or volume mesh consists of multiple regions that should have identical properties, region types and body forces and will be associated with the same continuum, two approaches can be used:
If you do not fuse the adjacent boundaries or create interfaces, the combined regions will be solved exactly as if they were still separate regions with the same properties. In general, it is more computationally efficient to fuse adjacent boundaries within a region than use internal interfaces.
It does not matter if the regions being combined are contiguous or not. In STAR-CCM+ you can have a single region that is non-contiguous, and you can split a non-contiguous region if desired.
To combine regions, select the regions of interest (using multiple selection) and right-click. Select Combine... from the pop-up menu.
The Combine Regions dialog will be displayed, allowing you to choose whether to combine boundaries with similar names from the selected regions or fuse adjacent boundaries.
The regions to be combined should appear in the Selected list box. If you click the Combine boundaries with similar names option, any boundaries from the combined regions that have the same base names will be combined. Boundary names which are the same up to the first included space will be combined, so for example, Symmetry 8 and Symmetry 62 would be combined, while Symmetry-8 and Symmetry-62 would not be. If you do not activate this option, STAR-CCM+ will append a space and a digit to the name of one of two boundaries that have the same name.
Tick the Fuse adjacent boundaries checkbox to enable fusing. The Fuse conformal faces only and Tolerance options are only enabled if Fuse adjacent boundaries is ticked. See the description of the Fuse Boundaries dialog for details of the Fuse conformal faces only and Tolerance options. Clicking OK begins the combination operation.
Once the operation is complete, a summary of the operation is written to the Output window.
If the regions to be combined contain interfaces then these will be reset and any vertices created by the intersection process will be removed. Faces and vertices may also be removed from other regions if the interfaces being reset reference them. Initializing or performing an iteration will re-intersect any interfaces which were reset during the region combine operation. In general, it is more efficient to complete any region and boundary manipulations before creating interfaces or initializing the solution.
The simulation tree will be updated to reflect the new topology.
The name of the combined region is the same as the name of the region that was first selected in the multiple selection process. Note that you can only combine regions if one mesh representation is present.