Emergent Chirality and Current Generation

Abstract

We investigate the phenomenon of producing vibration-induced rotational motion in a cylinder filled with achiral rods and being vibrated by an external drive. The arrangement of the rods develops chirality as a result of the interaction of gravity and steric hindrance, which is responsible for the induced motion. A two-rod arrangement is sufficient to generate a persistent motion. The average angular velocity $⟨\omega ⟩$ of the rods at long times varies non-monotonically with the packing fraction $\varphi$ for a given drive strength $\Gamma$. Though the precise nature of the variation of $⟨\omega ⟩$ with $\varphi$ depends on the details of the interaction between individual rods, its general characteristics hold true for rods of various materials and geometries. A stochastic model based on the asymmetric simple exclusion process helps in understanding the key features of our experiments.

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