We focus on the understanding of individual and collective behavior of material particles interacting with a turbulent flow in order to improve models of dispersion and transport. We develop Lagrangian acoustic (Doppler velocimetry) or imaging techniques to measure the velocity and the acceleration of individual particles in grid turbulence, jet turbulence or turbulent channel flow. The collective dynamics is explored using high-speed imaging of the concentration field and the dynamics of a fog of droplets in grid turbulence.
