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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 19: Active Matter III (joint session DY/BP/CPP)
CPP 19.3: Talk
Tuesday, March 18, 2025, 10:00–10:15, H47
Order by disorder in a swarm with obstacles — Pradeep Kumar1, Sanjay Puri1, and •Martin Weigel2 — 1School of Physical Sciences, Jawaharlal Nehru University, New Delhi – 110067, India — 2Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany
Simple models of swarming and active matter such as the Vicsek model [1] have been
studied in detail, and the phase diagram as a function of noise strength and particle
density is by now well understood. Real active systems are usually affected by
impurities and random disorder, however. The presence of a quenched distribution of
disc-like obstacles in the domain of the Vicsek model is observed to have a dramatic
effect on the ordering behavior [2]: in contrast to the model without obstacles,
where the strongest alignment is observed for the lowest noise, as soon as obstacles
are added only the presence of a certain amount of noise leads to a global alignment
of particles. This order by disorder phenomenon for active systems is traced back to
the interplay of multiple length scales in the system: the typical inter-obstacle
distance, the typical cluster size, and the resulting mean-free-paths of
cluster-obstacle and cluster-cluster collisions. We present scaling arguments
explaining these connections and provide an outlook towards similar phenomena in
related systems.
[1] T. Vicsek, Phys. Rev. Lett. 75, 1226 (1995).
[2] O. Chepizhko, E. G. Altmann, and F. Peruani, Phys. Rev. Lett. 110, 238101 (2013).
Keywords: Vicsek model; quenched disorder; phase transitions