Programmable transport of rotating particles in obstacle arrays

Abstract

Rotating colloids, or spinners, in obstacle arrays exhibit frequency-set stationary orbits and currents set by the competition between an inertial, Magnus-like lift and short-range attraction. Fully resolved lattice-Boltzmann simulations reveal the hydrodynamic coupling and identify the lift mechanism, while a symmetry-based Langevin model captures the resulting balance. In periodic lattices, the superposition of scalar and vector potentials produces two robust orbital regimes: corner states, in which spinners orbit individual posts, and inner states, in which orbits couple across four neighboring obstacles. Slow frequency modulation toggles these states and produces directed, stepwise transport across the grid. This establishes a minimal hydrodynamic mechanism, controlled by a single driving parameter, for programmable guidance of active rotors in structured environments.

9 pages, 7 figures

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