## 10.2. Composite Regions

Composite regions are regions defined in terms of other regions. For example:

- A named Region “A” may be an alias for another Region “B”

  A composite region that is an alias can directly reference only one other region, but may reference more than one region if the region it references is itself another composite region.

- Region “C” may be a union (that is, all) of Region “D” and Region “E”.

  A composite region that is a union will reference one or more other regions directly and may indirectly reference many other regions if the regions it references themselves reference other regions.

Composite regions ultimately resolve to primitive regions.

The tree view and the Region details view are used to select, create, rename, modify, and delete composite regions.

If any of the primitive regions to which a composite region resolves does not exist in the model, the composite region is said to be unresolved.

Composite regions can be defined in terms of 2D and 3D primitive regions. If the composite region resolves to both 2D and 3D primitive regions, the composite region is known as a mixed dimensionality composite.

An Assembly is a special case of a mixed-dimensionality composite region. It can be used in the same way, but its composition implies connectivity within the mesh. All 3D mesh volumes within an Assembly ‘know’ about their connections to each other. This information is used by CFX-Pre when calculating interfaces between domains.

Composite regions that are specified in the original mesh file imported into CFX-Pre will be imported into the application if the import format can be translated into one that CFX-Pre can use. The composite regions imported into CFX-Pre can be selected, modified, and deleted in the same way as composite regions defined in CFX-Pre.

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