The behaviour of small inertial particles in homogeneous and isotropic turbulence

The description of the statistical properties of small inertial particles sus- pended in turbulent flows is an important problem within fluid dynamics in general, and cloud physics in particular. For passively advected particles, in recent years a large number of experi- mental and numerical observations has been collected, mostly in the simplest situation of homogeneous and isotropic turbulence (HIT). I will review some results obtained in direct numerical simulations of HIT about small scale properties of inertial particles velocity statistics and spatial distribution. In particular, I will try to highlight effects for which gravita- tional accelerations matters.