Author(s): Joan Codina, Benoît Mahault, Hugues Chaté, Jure Dobnikar, Ignacio Pagonabarraga, and Xia-qing Shi
We show that arbitrarily large polar flocks are susceptible to the presence of a single small obstacle. In a wide region of parameter space, the obstacle triggers counterpropagating dense bands leading to reversals of the flow. In very large systems, these bands interact, yielding a never-ending cha…
[Phys. Rev. Lett. 128, 218001] Published...