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arXiv · 1404.3086

A Boltzmann model for rod alignment and schooling fish

Eric a. Carlen·Maria C. Carvalho·Pierre Degond·Bernt Wennberg
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Abstract

We consider a Boltzmann model introduced by Bertin, Droz and Greegoire as a binary interaction model of the Vicsek alignment interaction. This model considers particles lying on the circle. Pairs of particles interact by trying to reach their mid-point (on the circle) up to some noise. We study the equilibria of this Boltzmann model and we rigorously show the existence of a pitchfork bifurcation when a parameter measuring the inverse of the noise intensity crosses a critical threshold. The analysis is carried over rigorously when there are only finitely many non-zero Fourier modes of the noise distribution. In this case, we can show that the critical exponent of the bifurcation is exactly 1/2. In the case of an infinite number of non-zero Fourier modes, a similar behavior can be formally obtained thanks to a method relying on integer partitions first proposed by Ben-Naim and Krapivsky.

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Eric a. Carlen, Maria C. Carvalho, Pierre Degond, Bernt Wennberg. 2014-04-11. A Boltzmann model for rod alignment and schooling fish. https://doi.org/10.1088/0951-7715%2F28%2F6%2F1783

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