Setting Overset Properties on Boundaries

Inflow occurs through a stagnation inlet boundary with an inlet total pressure of 0 Pa. The flow leaves the domain through a pressure outlet boundary. The casing of the pump is modelled through rigid stationary wall boundaries at the top and bottom of the geometry. An overset boundary encompasses the side surface of each lobe overset region. The top and bottom boundaries of each lobe overset region coincide with the top and bottom boundaries of the background region, and slide along them as the overset regions move. Therefore, the top and bottom boundaries of the overset regions must be of the same type as the corresponding boundaries of the background region, which here is a wall boundary.

For more information on this requirement, see Preparing Overset Regions.

By default, the top and bottom wall boundaries of the lobes rotate with the rotating regions as per the motion definition. To mimic static behavior for these wall boundaries, you change the frame of reference of the boundary to be the laboratory frame of reference. Prism layer shrinkage generally moves all prism layer cells at wall boundaries when they get close. To avoid this behaviour at the outside walls of the lobes and the casing, you deactivate prism layer shrinkage at the top and bottom wall boundaries of both overset regions and the background region.