Collective behavior of self-propelled rods with quorum sensing

Clara Abaurrea Velasco, Masoud Abkenar, Gerhard Gompper, and Thorsten Auth
Phys. Rev. E 98, 022605 – Published 13 August 2018
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Abstract

Active agents—like phoretic particles, bacteria, sperm, and cytoskeletal filaments in motility assays—show a large variety of motility-induced collective behaviors, such as aggregation, clustering, and phase separation. The behavior of dense suspensions of engineered phoretic particles and of bacteria during biofilm formation is determined by two qualitatively different physical mechanisms: (i) volume exclusion (short-range steric repulsion) and (ii) quorum sensing (longer-range reduced propulsion due to alteration of the local chemical environment). To systematically characterize such systems, we study semi-penetrable self-propelled rods in two dimensions, with a propulsion force that decreases with increasing local rod density, by employing Brownian dynamics simulations. Volume exclusion and quorum sensing both lead to phase separation; however, the structure of the systems and the rod dynamics vastly differ. Quorum sensing enhances the polarity of the clusters, induces perpendicularity of rods at the cluster borders, and enhances cluster formation. For systems where the rods essentially become passive at high densities, formation of asters and stripes is observed. Systems of rods with larger aspect ratios show more ordered structures compared to those with smaller aspect ratios, due to their stronger alignment, with almost circular asters for strongly density-dependent propulsion force. With increasing range of the quorum-sensing interaction, the local density decreases, asters become less stable, and polar hedgehog clusters and clusters with domains appear.

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  • Received 20 March 2018
  • Revised 22 June 2018

DOI:https://doi.org/10.1103/PhysRevE.98.022605

©2018 American Physical Society

Physics Subject Headings (PhySH)

Physics of Living SystemsPolymers & Soft Matter

Authors & Affiliations

Clara Abaurrea Velasco*, Masoud Abkenar, Gerhard Gompper, and Thorsten Auth

  • Theoretical Soft Matter and Biophysics, Institute of Complex Systems and Institute for Advanced Simulation, Forschungszentrum Jülich, D-52425 Jülich, Germany

  • *c.abaurrea@fz-juelich.de
  • g.gompper@fz-juelich.de
  • t.auth@fz-juelich.de

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Issue

Vol. 98, Iss. 2 — August 2018

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