Active Particles with Soft and Curved Walls: Equation of State, Ratchets, and Instabilities
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Author(s) • • • • •
Nikola, Nikolai
Kafri, Yariv
Tailleur, Julien
Voituriez, Raphaël
Solon, Alexandre
Kardar, Mehran
Date Issued
August 2016
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Nikola, Nikolai, Alexandre P. Solon, Yariv Kafri, Mehran Kardar, Julien Tailleur, and Raphaël Voituriez. Phys. Rev. Lett. 117, 098001 (2016).
Version
Final published version
Abstract
We study, from first principles, the pressure exerted by an active fluid of spherical particles on general boundaries in two dimensions. We show that, despite the nonuniform pressure along curved walls, an equation of state is recovered upon a proper spatial averaging. This holds even in the presence of pairwise interactions between particles or when asymmetric walls induce ratchet currents, which are accompanied by spontaneous shear stresses on the walls. For flexible obstacles, the pressure inhomogeneities lead to a modulational instability as well as to the spontaneous motion of short semiflexible filaments. Finally, we relate the force exerted on objects immersed in active baths to the particle flux they generate around them.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.117.098001