The self-organization of capillary waves sources
Résumé
A liquid drop can be kept bouncing at the surface of a bath of the same liquid for any length of time if the bath is kept oscillating vertically. Several regimes can be observed. For a liquid of moderate viscosity, the bouncing of the drop generates damped capillary waves with a wavelength corresponding to the forcing frequency. Therefore when several identical drops are placed on the oscillating surface, the interaction of their waves leads to the self-organization of the drops with a 2D triangular lattice. Another remarkable regime is observed when the forcing amplitude is increased close to the Faraday instability threshold: the drop starts moving in the horizontal plane at a constant velocity. We have studied the movement of one 'walking drop' as well as the possible interactions of several of these particular drops placed on the surface of the liquid, leading to their complex self-organization. These drops can collide via their waves and in certain situations attract each other and start orbiting.
