6.8.9 Replacing, Deleting, Deactivating, and Activating Zones

ANSYS FLUENT allows you to append or replace the existing cell zone in the mesh. You can also permanently delete a cell zone and all associated face zones, or temporarily deactivate and activate zones from your ANSYS FLUENT case.

Replacing Zones

This feature allows you to replace a small region of a computational domain with a new region of different mesh quality. This functionality will be required where you may want to make changes to the geometry or mesh quality for any part of the domain. This ability of ANSYS FLUENT will save you time, since you can modify only the required part of the domain without remeshing the whole domain every time.

The replacement mesh must be conformal with that of the old mesh, and must be of the same zone type.

Replacing a zone is performed using the Replace Cell Zone dialog box (Figure  6.8.6).

Mesh $\rightarrow$ Zone $\rightarrow$ Replace...

Figure 6.8.6: The Replace Cell Zone Dialog Box

To replace a zone, do the following:

1.   Click Browse... and select the new or modified mesh containing the cell zone which will replace the cell zone in the current mesh.

  The zone names of the new mesh will be listed under the Replace with list box.

ANSYS FLUENT checks for all face zones that have the same name as the face zones that will be deleted as a result of the replacement, and applies the old boundary conditions.

2.   Under Existing Zones, select the zone you want to replace. Note that the new cell zone might not have the same name as the old cell zone.

   ANSYS FLUENT will first separate all the face zones which are connected to any zones that will not be deleted as a result of the replacement in the current mesh. The cell zone being replaced is then totally separated and will be deleted by ANSYS FLUENT without affecting anything else.

3.   Under Replace with, select the zone from the newly read mesh.

4.   Click Replace to replace the selected zone. ANSYS FLUENT stitches the two-sided walls, creating sliding interfaces, and restores the condition of the mesh to its original form.

Deleting Zones

To permanently delete zones, select them in the Delete Cell Zones dialog box (Figure  6.8.7), and click Delete.

Mesh $\rightarrow$ Zone $\rightarrow$ Delete...

Figure 6.8.7: The Delete Cell Zones Dialog Box

All of the cells, faces, and nodes associated with the cell zone will be deleted. If one of the faces is of type interior and borders another cell zone, the face will automatically be changed to a wall and will stay attached to the remaining cell zone.

Deactivating Zones

To deactivate zones, select them in the Deactivate Cell Zones dialog box (Figure  6.8.8), and click Deactivate.

Mesh $\rightarrow$ Zone $\rightarrow$ Deactivate...

Figure 6.8.8: The Deactivate Cell Zones Dialog Box

Deactivation will separate all relevant interior face zones (i.e., fan, interior, porous-jump, or radiator) into wall and wall-shadow pairs.

Note:   When you deactivate a zone using the Deactivate Cell Zones dialog box, ANSYS FLUENT will remove the zone from the mesh and from all relevant solver loops.

To deactivate selected cell zones in parallel

1.   Read in the data file, or initialize your solution.

2.   Select the zone(s) to be deactivated under Cell Zones.

3.   Click the Deactivate button.

If you have neither read in the data file nor initialized the solution prior to clicking the Deactivate button, then the selected cell zones will only be marked for deactivation. The zones will not be deactivated until data is read or the solution is initialized.

Activating Zones

You can reactivate the zones and recover the last data available for them using the Activate Cell Zones dialog box (Figure  6.8.9) .

Mesh $\rightarrow$ Zone $\rightarrow$ Activate...

Figure 6.8.9: The Activate Cell Zones Dialog Box

Note:   The Activate Cell Zones dialog box will only be populated with zones that were previously deactivated.

After reactivation, you need to make sure that the boundary conditions for the wall and wall-shadow pairs are restored correctly to what you assigned before deactivating the zones. If you plan to reactivate them at a later time, make sure that the face zones that are separated during deactivation are not modified. Adaption, however, is supported.

To activate selected cell zones in parallel

1.   Read in the data file, or initialize your solution.

2.   Select the zone(s) to be activated under Cell Zones.

3.   Click the Activate button.

If you have neither read in the data file nor initialized the solution, prior to clicking the Activate button, then the selected cell zones will only be marked for activation. The zones will not be activated until data is read or the solution is initialized.