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arXiv · 1709.02281

Generic long-range interactions between passive bodies in an active fluid

Yongjoo Baek·Alexandre P. Solon·Xinpeng Xu·Nikolai Nikola·Yariv Kafri
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Abstract

Because active particles break time-reversal symmetry, a single non-spherical body placed in an active fluid generates currents. We show that when two or more passive bodies are placed in an active fluid these currents lead to long-range interactions. Using a multipole expansion we characterize their leading-order behaviors in terms of single-body properties and show that they decay as a power law with the distance between the bodies, are anisotropic, and do not obey an action--reaction principle. The interactions lead to rich dynamics of the bodies, illustrated by the spontaneous synchronized rotation of pinned non-chiral bodies and the formation of traveling bound pairs. The occurrence of these phenomena depends on tunable properties of the bodies, thus opening new possibilities for self-assembly mediated by active fluids.

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Yongjoo Baek, Alexandre P. Solon, Xinpeng Xu, Nikolai Nikola, Yariv Kafri. 2017-09-07. Generic long-range interactions between passive bodies in an active fluid. https://doi.org/10.1103/physrevlett.120.058002

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