Underlying element X instance Y can only have spos or sneg as a face identifier - heat transfer

[bothul]

Dear all,

I have created a part consisting of 2 perpendicular shell surfaces. I partitioned the part using datum plane (through both cells).
I want to use the part in a heat transfer analysis. When submitting the job I get the error

Underlying element X instance Y can only have spos or sneg as a face identifier

I was looking for the elements that were assigned this error and they are positioned along one of the edges that is partitioning the part and only on one side of the partitioning edge. It is curious that only elements belonging to the extruded surface are included in the error set.

Is there a way to fix this error?

Thank you
Best regards,

 

[corus]

A picture would have helped but I think you are trying to impose a boundary condition on an edge of a shell element rather than the face SPOS or SNEG. That edge, I guess, is on the intersection with a perpendicular plane that has that boundary condition. When selecting the face make sure you haven't also selected the erroneous edge. I think you do that by using the ctrl key to select the edge so that it's removed from the current selection.