Experimental study on the clustering of floaters on the free surface of a turbulent flow

Pablo Gutiérrez, Sébastien Aumaître

Published 2014-10-28Version 1

We present an experimental study of the statistical properties of millimetric spheres floating on the surface of a turbulent flow. The flow is generated in a layer of liquid metal by an electromagnetic forcing. \textcolor{red}{By using two magnet arrays,} we are able to create one highly fluctuating flow and one almost stationary flow. In both cases, we follow the motion of hundreds of millimeter-size particles floating at the deformed interface of the liquid metal. We evidence the clustering of floaters by a statistical study of the local density of particles. Some dynamical properties of clusters are exposed. With the almost stationary flow obtained with the random array of magnets, we are able to relate the cluster formation to compression effects. Hence, although floaters are not passive scalar and move on a disturbed interface, we propose that the main clustering effect is the same as the one reported for passive scalar on an almost flat surface of a turbulent flow.