Topological changes of the grid in a flow simulation based on mesh-based finite volumes are a major challenge. One of the classic applications in engineering practice is the opening and closing of valves, such as flutter valves or inlet/exhaust valves in piston engines.
The state change of a valve from still currently open to the fully closed state is a singularity. Not only a topology change in the mesh is a result, but also the sudden stop of the flow rate through the valve.
With the meshless method SPH these restrictions are eliminated, as the shown example illustrates.
A liquid is pressed into a tubular impermeable membrane made from hyper-elastic material. At the lower end of the tube a rigid lid is fixed in space. The tube is in this case not firmly attached to the lid.