Séminaire PMMH

Vendredi 8 octobre 11:00-12:00 - Salle réunion PMMH 1

Dynamics and collisions of anisotropic particles settling in a turbulent flow : application to cloud microphysics

Aurore Naso, LMFA, Lyon

I will present recent results related to the settling of small anisotropic particles in a turbulent flow.

It will be first shown that fluid inertia can, surprisingly, play an important role on the orientation of such objects, despite their small size. We will introduce a parameter allowing to predict the regimes in which particles orientation is essentially driven by the inertial torque (and therefore preferentially horizontal) and those in which the viscous torque prevails.

The results of numerical simulations characterizing the settling, orientation and collisions between very flat particles in a turbulent flow will be then presented and discussed. This investigation has been carried out in a parameter range relevant for the dynamics of ice crystals in clouds.

The last part of the talk will be devoted to the investigation of collisions between anisotropic and smaller spherical particles, modelling respectively the ice crystals and supercooled water droplets that can coexist in mixed-phase clouds.