We study the propagation of waves in a medium which wave velocity fluctuates randomly time. prove that at long times, statistical distribution energy is log-normal, with average growing exponentially. For weak disorder, another regime preexists shorter follows negative exponential distribution, an value linearly The theory perfect agreement numerical simulations, and applies to different kinds ...

We study experimentally how waves affect the distribution of particles that float on a liquid surface. We show that clustering of small particles in a standing wave is a nonlinear effect with the clustering time decreasing as the square of the wave amplitude. In a set of random waves, we show that small floaters concentrate on a multifractal set with caustics.