Statistics of preferential particle concentration in free-surface

Particles floating on a turbulent surface of water cluster into temporally complex patterns. We experimentally study the statistics of this preferential particle concentration for various Reynolds numbers, for both transient and steady-state dynamics. The probability density function for particle concentration exhibits a power-law with an exponential cut-off. We will discuss our preliminary analysis as to how this distribution depends upon the Reynolds number and the spatial-scale $r$ at which the system is coarse-grained.