Self-organization of bouncing drops
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)Abstract
A liquid drop can be kept bouncing on the surface of a bath of the same liquid for any length of time if the bath is kept oscillating vertically 1. 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 crystalline lattice.
Just below the Faraday instability threshold, a remarkable phenomenon occurs when the drop undergoes a drift bifurcation and starts moving horizontally at the surface of the liquid, acquiring a constant horizontal velocity. We call such drops walkers. We have studied this transition from a steady bouncing drop to a walker and described it theoretically 2, 3.
We have also observed the various interactions (always via their waves) of several walkers moving across the cell 4. This interaction is non-trivial being attractive or repulsive. The attractive collision of two walkers can lead to the orbiting motion of the two drops.
1) Couder Y., Fort E., Gautier C-H et Boudaoud A. (2005) Phys. Rev. Lett. 94 177801\\
2) Couder Y., Protičre S., Fort E. et Boudaoud A. (2005) Nature 437 208\\
3) Protičre S., Couder Y., Fort E. et Boudaoud A. (2005) J. Phys.: Condens. Mat 17 S3529\\
4) Protičre S., Boudaoud A. et Couder Y. (2006) J. Fluid Mech 554 85