How to prevent "segmentation violation" before the first iteration when starting from a saved case with periodic boundaries and mesh interfaces ?
Very likely the cause for this issue relates to the Mesh Interfaces. When mesh interfaces are located between periodic boundaries, ANSYS FLUENT sometimes builts additional periodic threads loosing linkage to their parent threads while being saved.
This causes a segmentation violation when trying to run the simulation from the saved case.
You can verify this error source for your case by deleting all interfaces from the saved (and reread) case. If unwanted boundary zones wall-xy and wall-shadow-xy still exist, you are facing the mentioned issue.
To resolve the problem, you have to prevent ANSYS FLUENT from creating the additional periodic threads by setting a scheme variable from the TUI as follows:
(rpsetvar 'nonconformal/allow-interface-at-periodic-boundary 0)
You have to do that BEFORE creating the Mesh Interfaces.
NOTE: You cannot heal an already "damaged" case by reading a BC-file and using the above rpsetvar command.