I am after cycloidal rotation.

The first idea is one rotating region inside another.

The posts from 2013-2014 seem to indicate this isn't supported.

Tried this on SW2016 - "Mesh Generation Terminated".

What are my chances here?

In "What's new in SW2018" I can still see a note "Phase transitions (including isothermal cavitation), high Mach number flows, and mixing plane rotation regions are not allowed" - it is being mentioned under "Sector Periodicity" feature, so not sure if its a global constraint of feature-specific?