KNOWN ISSUE: GGI CHT periodic boundaries give incorrect solutions (Class 3 Error)
In a conjugate heat transfer case with periodic boundaries, then rotational or translational solid-solid interfaces, which are not 1-1, will give rise to incorrect temperatures.
This is caused by incorrect discretization in the CFX-Solver.
If possible, use a mesh with one-one periodicity, and explicitly set a 1-1 type for the interface.
ANSYS CFX Release 12.1. A custom executable for ANSYS CFX Release 12.0 is available on request.