# Quincke rotor dynamics in confinement: rolling and hovering

## TL;DR

This paper investigates Quincke rotor behavior under confinement, revealing unsteady rolling and levitation regimes, with thresholds influenced by particle confinement, advancing understanding of electrohydrodynamic particle dynamics.

## Contribution

It experimentally demonstrates new regimes of Quincke rotor motion, including unsteady rolling and hovering, highlighting the role of confinement in threshold behaviors.

## Key findings

- Unsteady, time-periodic rolling observed at strong fields
- Sphere can levitate between electrodes in a new regime
- Confinement affects the onset thresholds for rotation and levitation

## Abstract

The Quincke effect is an electrohydrodynamic instability which gives rise to a torque on a dielectric particle in a uniform DC electric field. Previous studies reported that a sphere initially resting on the electrode rolls with steady velocity. We experimentally find that in strong fields the rolling becomes unsteady, with time-periodic velocity. Furthermore, we find another regime, where the rotating sphere levitates in the space between the electrodes. Our experimental results show that the onset of Quincke rotation strongly depends on particle confinement and the threshold for rolling is higher compared to rotation in the hovering state.