Tracking the rotation of light magnetic particles in turbulence

TL;DR

This paper introduces a novel experimental method to track the full rotational motion of small, magnetic particles in turbulent flows using a single camera, enabling detailed analysis and potential active control of turbulence.

Contribution

The paper presents a new technique for fully resolving the three-dimensional rotation of small magnetic particles in turbulence with minimal imaging equipment.

Findings

Successfully tracks all three components of particle angular velocity.

Enables detailed study of magnetic particle dynamics under turbulence and magnetic forcing.

Facilitates active turbulence modulation through external magnetic fields.

Abstract

Particle-laden turbulence involves complex interactions between the dispersed and continuous phases. Given that particles can exhibit a wide range of properties, such as varying density, size, and shape, their interplay with the flow can lead to various modifications of the turbulence. Therefore, understanding the dynamics of particles is a necessary first step toward revealing the behavior of the multiphase system. Within the context of particle dynamics, accurately resolving rotational motion presents a significantly greater challenge compared to translational motion. We propose an experimental method to track the rotational motion of spherical, light, and magnetic particles with sizes significantly smaller than the Taylor microscale, typically an order of magnitude larger than the Kolmogorov scale of the turbulence in which they are suspended. The method fully resolves all three components of the particle angular velocity using only 2D images acquired from a single camera. This technique enables a detailed investigation of the rotational dynamics of magnetic particles subjected simultaneously to small-scale turbulent structures and external magnetic forcing. Beyond advancing the study of particle dynamics in turbulence, this approach opens new possibilities for actively modulating turbulence through externally applied magnetic fields.