Although the purpose of the video is scientific, I find the movement of the dye incredibly beautiful and hypnotic. The high contrast makes the flow easily visible. I appreciate how the creator has included two different frequencies of this experiment because comparing the two creates a better visual understanding of the physics behind the vortexes created by the flapping foil.
Video by Ramiro Godoy-Diana, CNRS researcher at PMMH, ESPCI.
more of his work can be found at: https://blog.espci.fr/ramiro/home/