When adding a cylinder volume, what is the purpose of the property "decompose"?
The Decompose option splits a cylinder into six four-edged faces. Caedium has multiple level undo and redo so don't be afraid to experiment.
Thanks for your comment. Do these need to be reconnected before running a simulation?
Another question, are the velocities shown on a rotating volume, absolute or relative?
The decomposed cylinder is a valid manifold volume like all the other primitive volumes created in Caedium, so you don't need to stitch it into a volume.
Results velocity vectors are absolute. Field velocity vectors are interpolated to surfaces, so the surface values do not reflect your boundary conditions.