Thanks for your reply Bruno.

I am still working on this issue.... it appears as if there was some attempt to include "a base class for processor and cyclic tetPolyPatches" (as was stated in coupledFaceTetPolyPatchCellDecomp.H) so maybe there is someone out there who has already modified for periodic BCs..?

FYI - I started a new thread for my problem here:

http://www.cfd-online.com/Forums/ope...tions-fsi.html

I think I was a bit off topic of the original intentions of the thread...
Best,
David