Berlin 2018 – scientific programme

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BP: Fachverband Biologische Physik

BP 15: Postersession III

BP 15.99: Poster

Tuesday, March 13, 2018, 14:00–16:00, Poster B

Flocking without velocity-alignment — •Fernando Peruani and Lucas Barberis — Université Côte d'Azur

The spontaneous emergence of collective motion patterns is usually associated with the presence of a velocity alignment mechanism that mediates the interactions among the moving individuals. Despite of this widespread view, we show that several flocking behaviors can emerge in the absence of velocity alignment and as a result of short-range, position-based, attractive forces that act inside a vision cone. We argue that for this class of active systems three distinct macroscopic collective behaviors can be observed: i) the coarsening of aggregates with no orientational order, ii) the emergence of static, elongated nematic bands, and iii) the formation of moving, locally polar structures, which we call worms. We derive hydrodynamic equations for active particles interacting via position-based interactions to demonstrate that they belong to a distinct class of active systems fundamentally different from other active systems, including velocity-alignment-based flocking systems.