Angular dynamics of a small particle in turbulence

TL;DR

This paper derives an approximation for the angular dynamics of small, nearly spherical particles in turbulence, highlighting how local vortex stretching influences inertial corrections to Jeffery's equation.

Contribution

It introduces a new approximation for particle torque that accounts for local vortex stretching effects in turbulent flows.

Findings

Inertial corrections to Jeffery's equation are significant in turbulence.

Local vortex stretching impacts particle angular dynamics.

The derived model captures the influence of turbulence on particle rotation.

Abstract

We compute the angular dynamics of a neutrally buoyant nearly spherical particle immersed in an unsteady fluid. We assume that the particle is small, that its translational slip velocity is negligible, and that unsteady and convective inertia are small perturbations. We derive an approximation for the torque on the particle that determines the first inertial corrections to Jeffery's equation. These corrections arise as a consequence of local vortex stretching, and can be substantial in turbulence where local vortex stretching is strong and closely linked to the irreversibility of turbulence.