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Inertial particles in turbulence : preferential concentration and settling velocity
Turbulent flows laden with inertial particles occur in many industrial and environmental situations (pollutant dispersion, plankton, engine optimization…) During the last forty years, many properties of these flows have been evidenced, nevertheless, a model equation describing them is still out of reach, particularly regarding the back reaction of the particles on the carrier fluid or regarding the possible collective effects on the particles dynamics.
We show experimental and numerical results on the strong heterogeneities appearing in the concentration fields and try to identify possible collective effects leading to the existence of clusters that can live for times long compared to the large turbulent scales. We also review the various tools used to evidence and quantify preferential concentration.