Return valve, allowing the flow to go only in one direction. The ring adapts to the housing of the valve thus blocking the flow in the "wrong" direction.
The ring is incorporated as reduced FE-model, keeping only the first eigenmodes(s) of the structure.
Coupling as a classical Fluid-Structure-Interaction (FSI): fluid provides stresses to the structure, the structure returns the motion to the fluid as a boundary condition.
The video shows two cycles of load, observe the retardation of flow-blockage due to inertial effects of the fluid and the ring.