[zommuter]

I'm simulating a pump with its stator and rotor separated by an cyclicACMI. The rotor mesh is rotating (no MRF). Since the gap is very narrow at some points, I want them to be non-overlapping parts using ACMI's neighbourPatches. Now my question, which boundary conditions should I use where? The stator's walls are fixed and the rotor's ones rotating, obviously.


$FOAM_TUTORIALS/incompressible/pimpleFoam/RAS/oscillatingInletACMI2D (the only cyclicACMI tutorial case I could actually find) declares the blockage as type wall; in blockMeshDict, which makes sense either way. But in 0/U the blockage uses a noSlip condition, whereas all other non-interface walls have a movingWallVelocity of 0. The user guide on that states

Sets the velocity to the desired value for moving walls when employed in moving mesh cases

which is honestly confusing me a bit. The tutorial case seems to imply that velocity is relative to the moving wall, correct? On the other hand, noSlip "sets the patch velocity to (0 0 0)", which sounds very absolute (and identical to fixedValue (0 0 0)?). In the tutorial case I guess it makes sense; while the small box is moving up and down, it slides along fixed walls. So I think noSlip is also the proper choice for the rotor's blockage.


But what about the stator's blockage? That should be a moving wall of the rotor, not a stationary one. And while the rotor zone does rotate I wonder how to state "noSlip, but in the rotating mesh's frame". The boundary condition guide doesn't mention it, but deeper down in the API documentation I found rotatingWallVelocity while writing this post, is that the proper condition to select then?


That's what I'm going to try now anyway, but of course I'd appreciate input from anyone who already did something along this line.