Jeremie Bec
CNRS, Observatoire de la Cote d'Azur, Nice France

Abrupt growth of large aggregates by correlated coalescences in turbulent flow

The time evolution of a population undergoing coalescence or aggregation is classically addressed in terms of the Smoluchowski coagulation equation. This mean-field model is used to describe a broad range of processes ranging from polymerization, emulsification and flocculation to cloud droplet growth and planet formation. It relies on the assumption that successive mergers are uncorrelated from each other. We report evidences that such an approach fails when the coagulating species are dilute and transported by a turbulent flow. The Lagrangian motion involves correlated violent events that lead to an unexpected fast growth of the largest particles.