KNOWN ISSUE: A case with mesh motion, GGI interfaces and subdomains may not re-intersect (Class 3 Error)
A case with mesh motion, GGI interfaces and subdomains may produce incorrect results because the re-intersection of some GGI interfaces is not performed every timestep (as it should be) but just once at the start of the calculation.
In Release 11.0 and earlier, any GGI interface which involved a domain with mesh motion was re-intersected each timestep, in order to ensure that the intersection was properly taking account of the current mesh position.
In Release 12.0, this was changed (for performance reasons) so that any GGI interface which had the Mesh Motion option "Stationary" for all parts of the interface in a domain with mesh motion was not re-intersected, as this is unnecessary for a stationary interface. However, if a GGI interface is defined as Stationary, but it is on the surface of a subdomain which defines non-zero mesh motion, then the mesh motion specification on the subdomain overrides the mesh motion specification on the interface, and that GGI interface is no longer stationary. Therefore, it needs to be re-intersected every timestep. This is not being done in Release 12.0.
The problem can be identified by the lack of re-intersection information each timestep in the CFX Output File.
Set the expert parameter 'stationary interface reintersection = t' to force the re-intersection.
ANSYS CFX Release 12.1. A custom executable for ANSYS CFX Release 12.0 is available on request.