We normally think of fluids as soft and rounded, and - in contrast to crystals - completely without sharp corners or facets. In reality, flowing liquids can create sharp edges, corners and spiky needles, and spontaneously break the symmetry of the experimental setup, even in stationary flow. The understanding and applications of such flow states is in rapid evolution and surprising new discoveries are frequent in this “classical” area poineered by scientists such as Savart, saint-Venant, Stokes, Plateau, Rayleigh, Prandtl and Taylor. Our scientific activities center around such
flow states and the
instabilities that cause them, in particular in cases where free surfaces are involved.
At the moment our main interests are hydraulic jumps and their polygonal states, sand ripples in oscillatory flow,
bathtub vortices and fluid flows in living organisms.