The mesh superposition technique also has several limitations:
It can be used only for 2D planar and 3D models.
Currently, it can be applied only to generalized Newtonian flow.
The detailed variation of the velocity in the neighborhood of the moving part is not well resolved.
As the physical boundaries do not match finite-element limits, the mass conservation equation
cannot be satisfied in every element; as a result, you may
see some limited fluid leakage.