Nodal patterns of floaters in surface waves
Fluid Dynamics Laboratory, The University of Hull, Hull, HU6 7RX, UK
2 Physics of Complex Systems, The Weizmann Institute of Science, Rehovot, 76100, Israel
Corresponding author: S.Lukaschuk@hull.ac.uk
We argue theoretically and demonstrate experimentally that in a standing wave floating particles drift towards the nodes or anti-nodes depending on their hydrophilic or hydrophobic properties. We explain this effect as the breakdown of Archimedes' law by a surface tension, which creates a difference between the masses of the floater and displaced liquid, making the particle effectively inertial. We describe analytically the motion of a small floating particle in a small-amplitude wave and show that the drift appears as a second order effect in wave amplitude. We confirm experimentally that indeed the clustering rate is proportional to the square of the wave amplitude. In the case of surface random waves we show experimentally that the inertial effects significantly change the statistics of floater distribution on a liquid surface. The analysis of particle concentration moments and probability distribution functions shows that particle concentrate on a multi-fractal set with caustics.
© EDP Sciences, Springer-Verlag, 2007