In multi-phase or multi-component systems with immiscible fluids phase interfaces are moving. Frequently, only the movement of the fluid or the motion of the phase interface is of interest. Interactions at the interfacial are either neglected or approximated based on simplistic models. The domain of the flow simulation is then dynamically defined via the phase boundary. With a mesh-based finite volume method, the solution field of the flow solver and the boundary conditions, however, has to be defined a priori.
With SPH, this restriction it no longer present, which is illustrated by the three examples.
At the end of a rigid pipe is a flexible hose. With the aid of a piston at the end of the pipe the fluid is shifted through the rigid pipe at a constant velocity of 0.2 m/s, 0.6 m/s and 1.8 m/s, and exits the flexible hose under the influence of gravity.
The examples illustrate not only the different behavior of the fluid in the tube itself, but also show the very different solution area.