Local flow measurements around flexible filaments under rotating magnetic field

TL;DR

This study combines experimental and numerical approaches to analyze the flow fields generated by rotating flexible magnetic filaments, providing insights for improving microfluidic mixing devices.

Contribution

It introduces a combined experimental and numerical analysis of hydrodynamics around rotating flexible ferromagnetic filaments, which was previously lacking.

Findings

Rotating filaments hover above the surface with fluid velocities depending on hovering distance.

Flow is three-dimensional, originating from the rotational plane and extending along the rotation axis.

Results aid in designing more effective micromixers for microfluidic applications.

Abstract

Effective mixing of fluids at the microfluidic scale is important for future applications in biology, medicine, and chemistry. A promising type of micromixers are magnetic filaments, which can be activated by an external magnetic field. However, there is a lack of research that combines experiments and numerical modelling of hydrodynamics around such filaments. Here we use micro-particle image velocimetry to measure flow fields around rotating flexible ferromagnetic filaments and compare them to numerical data from elastic rod model. We measure that rotating filaments hover above the surface, whereas the resulting fluid velocities are highly dependent on the hovering distance. We also find that the rotating filament causes a 3D flow coming from the rotational plane and being extracted along the axis of rotation. These findings will help develop better micromixers.