I want to use cfx11 to simulate helical pipes. For computational reasons, I would like to consider only a small portion of the pipe and NOT an entire pitch. My problem consists in the boundary conditions at inlet-outlet sections. In fact, it is possible to impose 'rotational' or 'translational' periodicity, but they are not adequate. I just want to 'glue' inlet and outlet, in such a way that flow exiting from outlet enters in the inlet.

Has somebody any suggestion?

You can run the same .def but the new inlet condition would be the old outlet condition (calculated in previous simulation). So you could run as many simulation as pipe length you need.

Unfortunately I want to simulate fully developed flow conditions. Therefore I need periodic-like boundary conditions in a unique domain.