Patters in particles on free surfaces

Particles floating on a free surface above a turbulent flow tend to cluster because of the upwelling and downwelling motions in the fluid underneath. The types of patterns that form depend on the stretching and contraction rates of the flow as well as on the correlation times of the flow. With increasing divergence of the flow a transition from elongated structures to point like ones can be induced. Unexpectedly, we find that the presence of correlations can weaken the clustering of particles.