This merge request adds a new showcase for the free-surface lattice Boltzmann method: Zalesak's rotating disk (see DOI: 10.1016/0021-9991(79)90051-2). The test case features a slotted disk of gas, initialized in a 2D domain filled with liquid. Because of a constant rotating velocity field, the disk rotates around the center of the domain.
If the advection scheme of a multiphase model worked perfectly, the slotted disk would have the exact same shape after every full rotation.
