Collective Dynamics of Quincke Rollers with Fully Resolved Hydrodynamics

Quincke rollers are the active dielectric particles that run and tumble freely on a flat plate due to a torque generated by a uniform DC electric field applied perpendicular to the plate [1]. It has been reported experimentally that the Quincke rollers show a variety of unique collective dynamics such as disorder gas, polar liquid, and active crystal states [2]; however, the physical mechanisms behind their complex behaviors are poorly understood, particularly in their dense system because of the complicated interactions composed of hydrodynamic and electrostatic forces.

We report our successful simulations on the collective motions of Quincke rollers, which depends on the strength of dipole moment induced on a particle, the area fraction of particles, and the strength of interparticle attraction, with fully resolving the hydrodynamics of the system. In particular, we want to emphasize that the polar liquid is unstabilized by the lubrication effect acting between rotating particles at high densities.

[1] A. Bricard et al. Nature 503.7474 (2013): 95-98.

[2] A. Mauleon-Amieva et al. Phys. Rev. E 102.3 (2020): 032609.