Coherent structures and extreme events in rotating multiphase turbulent flows

TL;DR

This study uses high-resolution DNS to explore rotating turbulent flows with coherent structures, revealing their impact on particle concentration, extreme fluctuations, and particle dynamics influenced by forces like Coriolis and drag.

Contribution

It provides the first detailed analysis of how vertical coherent structures affect particle behavior and extreme events in rotating turbulence.

Findings

Vertical structures cause preferential concentration of inertial particles.

Extreme fluctuations are linked to interactions between structures and turbulence.

Forces like Coriolis significantly influence particle diffusion in rotating flows.

Abstract

By using direct numerical simulations (DNS) at unprecedented resolution we study turbulence under rotation in the presence of simultaneous direct and inverse cascades. The accumulation of energy at large scale leads to the formation of vertical coherent regions with high vorticity oriented along the rotation axis. By seeding the flow with millions of inertial particles, we quantify -for the first time- the effects of those coherent vertical structures on the preferential concentration of light and heavy particles. Furthermore, we quantitatively show that extreme fluctuations, leading to deviations from a normal-distributed statistics, result from the entangled interaction of the vertical structures with the turbulent background. Finally, we present the first-ever measurement of the relative importance between Stokes drag, Coriolis force and centripetal forces along the trajectories of inertial particles. We discover that vortical coherent structures lead to unexpected diffusion properties for heavy and light particles in the directions parallel and perpendicular to the rotation axis.