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(1) Presentation(s)

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Ven. 27/02/2015 14:00 Andromede, Bâtiment 11, Etage 3

Séminaire
PERUANI Fernando (Lab. J.A.Dieudonné Université de Nice - Sophia Antipolis)
Séminaire général de physique théorique
Collective motion in confined geometries

(Physique Théorique)


Sommaire:

We study the collective effects in collections of active particles in confined geometries with reflecting (specular) boundary conditions. Our analysis reveals various remarkable macroscopic features induced by the existence of a confinement. First, the often-observed ``boundary-following'' effect is a collective effect that requires particles to exhibit a velocity alignment mechanism. In the presence of a ferromagnetic alignment, particles self-organize in such a way that they start to rotate either clockwise or counterclockwise. For nematic alignment and below the critical point, half of the particles rotate clockwise while the other half counterclockwise. Interestingly, close to the critical point we observe that rotational order competes with metastable macroscopic structures, which we call bridges. We show that for both alignment mechanisms, the onset of orientational order is associated to a density instability by which the reflecting walls act effectively as attractive.


Pour plus d'informations, merci de contacter Clusel M.