Flow mesh rotation
I was looking through one of the bSSFP flow example notebooks and noticed that the mesh was rotated but the flow velocities were not. This means that the flow will not follow the mesh and will produce incorrect results.
Maybe it would be worth it to include mesh rotation functions that rotate both the mesh points and the velocity field. According to Pietro, mesh rotation may become more involved when Reynolds stress tensors are included, due to the mixing terms. Either way, this should be documented to avoid further confusion.