FAQ: Discovery AIM – Resolving message “Face(s) are candidates for more than one region interface”

Problem: While working with a Fluid-Solid Heat Transfer (Conjugate Heat Transfer / CHT) analysis, you might come across below message:

face(s) are candidates for more than one region interface. Either split these faces using a geometry editing tool, or change the interface generator location to exclude the ambiguous bodies.

Cause:

When region interface is created, it only allows one face to participate in one interface. If any face is trying to create interface with more than one face, the above message is thrown.

To better understand this scenario, consider below example for which this message has been reported.

To identify the faces which are candidates for more than one region interface, simply right-click on the message and select “Select Location” option. This will highlight the concerned faces. For better visualization, switch to “Workflow” tab and click the Flow task without clicking anywhere in the graphics screen. The concerned faces can now be clearly seen highlighted in orange color. See below snapshot.

As seen in the above image, it can be understood that the top face of the plate (in orange color) is trying to create interfaces with the bottom face of the 2 blocks. As mentioned above, one face can only be a part of one interface. However, in this case, the bottom face is trying to create an interface with 2 faces which is not allowed.

Recommended Solution:

To overcome this message, there is a very simple way:

1. Go to Geometry task and edit the geometry.
2. Go to Prepare tab and click “Imprint” tool.
3. Complete the operation to create imprints at highlighted locations.
4. Once done, close the editor and open Flow task.
5. Click “Region Interface generator” and regenerate the region interfaces. The message no more appears. The bottom face of the block is now associated with the new face of the plate created due to imprint.