Inertial clustering and emergent phase separation of spherical spinners

Abstract

We study the hydrodynamics of spherical spinners suspended in a Newtonian fluid at inertial regime. We observe a spontaneous condensation of the spinners into particle rich regions, at low but finite particle Reynolds numbers and volume fractions. The particle clusters have a coherent internal dynamics. The spinners form colloidal vortices surrounded by the fluid depleted of the particles. The formation of vortices is observed both in periodic simulation box and when the spinners are confined between two flat walls. The stabilisation of the observed states relies only on hydrodynamic interactions between the spinners and requires a finite amount of inertia. The observations pave the way for the realisation of 3-dimensional spinner materials, where coherent structures and collective dynamics arise only from the rotational motion of the constituents.

References in corpus (4)

• Optical alignment and spinning of laser-trapped microscopic particles
• Diffusive transport without detailed balance in motile bacteria: Does microbiology need statistical physics?
• Emergent vortices in populations of colloidal rollers
• Purely hydrodynamic ordering of rotating disks at a finite Reynolds number

Cited by in corpus (3)

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• Inertia-driven propulsion of asymmetric spinner-dimers at moderate Reynolds numbers