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arXiv · 1910.14341

Robust boundary flow in chiral active fluid

Xiang Yang·Chenyang Ren·Kangjun Cheng·H. P. Zhang
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Abstract

We perform experiments on an active chiral fluid system of self-spinning rotors in confining boundary. Along the boundary, actively rotating rotors collectively drives a unidirectional material flow. We systematically vary rotor density and boundary shape; boundary flow robustly emerges under all conditions. Flow strength initially increases then decreases with rotor density (quantified by area fraction $\phi$); peak strength appears around a density $\phi=0.65$. Boundary curvature plays an important role: flow near a concave boundary is stronger than that near a flat or convex boundary in the same confinements. Our experimental results in all cases can be reproduced by a continuum theory with single free fitting parameter, which describes the frictional property of the boundary. Our results support the idea that boundary flow in active chiral fluid is topologically protected; such robust flow can be used to develop materials with novel functions.

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Xiang Yang, Chenyang Ren, Kangjun Cheng, H. P. Zhang. 2019-10-31. Robust boundary flow in chiral active fluid. https://doi.org/10.1103/physreve.101.022603

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