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Main Title: Phase separation and coexistence of hydrodynamically interacting microswimmers
Author(s): Blaschke, Johannes
Maurer, Maurice
Menon, Karthik
Zöttl, Andreas
Stark, Holger
Type: Article
Language Code: en
Abstract: A striking feature of the collective behavior of spherical microswimmers is that for sufficiently strong self-propulsion they phase-separate into a dense cluster coexisting with a low-density disordered surrounding. Extending our previous work, we use the squirmer as a model swimmer and the particle-based simulation method of multi-particle collision dynamics to explore the influence of hydrodynamics on their phase behavior in a quasi-two-dimensional geometry. The coarsening dynamics towards the phase-separated state is diffusive in an intermediate time regime followed by a final ballistic compactification of the dense cluster. We determine the binodal lines in a phase diagram of Peclet number versus density. Interestingly, the gas binodals are shifted to smaller densities for increasing mean density or dense-cluster size, which we explain using a recently introduced pressure balance [S. C. Takatori, et al., Phys. Rev. Lett. 2014, 113, 028103] extended by a hydrodynamic contribution. Furthermore, we find that for pushers and pullers the binodal line is shifted to larger Peclet numbers compared to neutral squirmers. Finally, when lowering the Peclet number, the dense phase transforms from a hexagonal "solid'' to a disordered "fluid'' state.
Issue Date: 2016
Date Available: 24-Oct-2017
DDC Class: 530 Physik
Sponsor/Funder: DFG, SPP 1726, Mikroschwimmer - Von Einzelpartikelbewegung zu kollektivem Verhalten
Journal Title: Soft matter
Publisher: Royal Society of Chemistry
Publisher Place: Cambridge
Volume: 12
Issue: 48
Publisher DOI: 10.1039/c6sm02042a
Page Start: 9821
Page End: 9831
EISSN: 1744-6848
ISSN: 1744-683X
Appears in Collections:FG Statistische Physik weicher Materie und biologischer Systeme » Publications

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