There are a number of places in the Ansys Workbench and CFX applications where geometric faces and regions of mesh can be grouped together and assigned names. While this provides a large amount of flexibility, it can lead to confusion. To have more control over which groups of names are loaded into CFX to help simplify this issue, this section describes the ‘best practices’ for region definitions and is targeted mainly at Ansys CFD users of the DesignModeler, Meshing, and CFX applications.
Defining Names in the DesignModeler Application or the Meshing Application
When creating or importing geometry in the DesignModeler application or editing a mesh in the Meshing application, Named Selections can be defined in terms of one or more CAD faces. If it is desirable for these Named Selections to be available in CFX-Pre, then they must adhere to these simple rules: Named Selections should not overlap or be defined as multi-dimensional and all Named Selections must have unique names.
Importing DesignModeler Named Selections into the Meshing Application
If the Named Selections defined in the DesignModeler application are required in the Meshing application, you must set the appropriate geometry import options to ensure the Named Selections will be transferred properly:
From the Ansys Workbench Menu Bar, select .
In the left pane of the Options dialog box, select Geometry Import.
In the right pane of the Options dialog box, select the Named Selections check box and either clear the Filtering Prefixes field (to import all names) or set it to the appropriate filter if required.
The next time that you attach geometry containing Named Selections and launch the Meshing application, the application will start, load the geometry, and load any Named Selections previously defined for that geometry. The preferences you set on the Options dialog box are local settings and affect only you.
If a mesh is generated, the Named Selections defined in the DesignModeler application will be available when the mesh is imported into CFX-Pre.
Note: For detailed descriptions of the geometry import options, see the CAD Integration section in the ANSYS Workbench help.
Using Multiple Mesh Methods
Named Selections can be defined in the Meshing application, the DesignModeler application, or supported CAD systems. When the resulting mesh is loaded into CFX-Pre, all of these Named Selections are available. Control over which names are imported with the mesh is available in the Mesh Import options.
It is possible to define Named Selections that conflict with some virtual topology, or do not conform to the CFX Topology Model in some other way. Such Named Selections will not be imported into CFX-Pre.
If a Named Selection is created that contains characters not supported in CFX-Pre names, these names will be modified on import to remove the illegal characters. Note that non-ASCII characters are illegal in CFX-Pre names.
Invalid Named Selections
The use of Virtual Topology within the Meshing application can invalidate Named Selection definitions. Consider the case where a Named Selection ‘Region1’ is defined in terms of 4 CAD faces (1, 2, 3 and 4). If this geometry is then loaded into the Meshing application and Virtual Topology is used to merge 2 of these faces (3 and 4), the original Named Selection can no longer be resolved. In CFX-Pre, the Named Selection will be modified so that it only refers to the ‘resolvable’ faces. Hence, in CFX-Pre, the Named Selection ‘Region1’ would be defined in terms of faces 1 and 2 only.
Named Selections Involving Interior Faces
If an interior face (for example, a face that is shared between two bodies in the same part in DesignModeler) is included in a Named Selection in the Meshing application, then the corresponding location in CFX-Pre will be a Composite region that includes two Primitive regions: one for each side of the interior face. Care should be taken when using the resulting Composite region for evaluating expressions and performing calculations: for example, areas evaluated on such a Composite region would be likely to give double the expected result (since the area is evaluated over both of the primitive regions that form the two sides of the interior face) and mass flows will be approximately zero (since the mass flow is evaluated on both of the primitive regions and will have the opposite sign on each). You can optionally edit the Composite region in CFX-Pre to include only one of the primitive regions.