Fragmentation of a graphite floating raft by water surface waves.
When particles of a few tens of microns are spread on the surface of water, they aggregate unde rthe action of capillary forces and form a thin floating membrane, a particle raft. In an experimental tank with a raft made of graphite powder, we generate gravity surface waves, whose wavelength is very large compared to the thickness of the raft. For a sufficiently strong wave amplitude, the raft breaks up progressively by producing fragments whose sizes decrease on a time scale long compared to the period of the wave. The visual appearance of the fragments surrounded by open water bears a striking resemblance to the floes produced by the fracturing of sea-ice by waves in the polar oceans. Fragmentation concepts and morphological tools built for sea-ice floes could be applied to our macroscopic analog, on which the entire dynamical evolution is accessible.