From the disperion of pollutants in the atmosphere to fuel injection in car engine, particles in turbulence are everywhere. Fluid motion is often chaotic and the transport of particles is strongly influenced by both particles properties (like their size, shape, density) and the statistical properties of the turbulent velocity field. How do particles get disperse in a turbulent flow? How is rain formed in clouds? How do droplets coalesce to form larger droplet? These and many other fundamental scientific questions rely on the accurate understanding of the small scale dynamics of particles or droplest (collisions, coalescence, breakup processes) evolving in a velocity field with non trivial correlations over a large span of scales and times.
Over recent years this field of research has been growing rapidly thanks to renewed experimental techniques. For the firat time ever it has become possible, for experiments, to record both high frequency and long time (cleary a technically conflicting requirement) trajectories of particles. The simultaneous increase in computational resources also allowed very detailed investigations of the evolution of statistical particles in several flow geometries.
Further details can be found here: http://lorentzcenter.nl/lc/web/2012/488/info.php3?wsid=488