Flow Generation by Rotating Colloids in Planar Microchannels

TL;DR

This study uses mesoscale hydrodynamics simulations to explore how rotating magnetic colloids generate flow in microchannels, revealing laning in straight channels and net fluid transport in ring channels due to curvature effects.

Contribution

It demonstrates how channel geometry influences flow generation by spinning colloids, highlighting the role of curvature in breaking symmetry and inducing net fluid transport.

Findings

Laning occurs in straight channels with spinning colloids.

Curvature in ring channels causes net fluid flow in the same direction as colloid rotation.

Flow velocity depends on channel width, ring radius, colloid concentration, and thermal motion.

Abstract

Non-equilibrium structure formation and conversion of spinning to translational motion of magnetic colloids driven by an external rotating magnetic field in microchannels is studied by particle-based mesoscale hydrodynamics simulations. For straight channels, laning is found. In ring channels, the channel curvature breaks symmetry and leads to a net fluid transport around the annulus with the same rotational direction as the colloidal spinning direction. The dependence of the translational velocity on channel width, ring radius, colloid concentration, and thermal motion is predicted.