title: Clustering of passive particles by Random Waves

Common knowledge is that random flow mixes.
Can a random flow lead to clustering of passive particles?
It can. The fluid should be compressible.
In particular, people considered delta-correlated velocity field
and found that clustering is proportional to the potential component.
In our case, the velocity field has short correlation time, but not
zero.
We find that the clustering is proportional to the product of solenoidal
and potential components;
if the flow is purely solenoidal or purely potential, there is no
clustering.