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Système expérimental modèle d'un fluide actif polaire

Abstract : Collective motion, such as flocks of birds or shoals of fish, is ubiquitous in nature. Physicists describe such fundamentally out-of-equilibrium phenomena with the new conceptual background of polar active matter. It is a system of polar particles, i.e. enable to use provided energy in order to move in their own directions. We have set up an 2D experimental system of vibrated polar disks that interact only by contact. These disks behave as random walkers, whose trajectories are characterized by a persistence length greater than their size and controlled by the angular fluctuations of their polarity. The interplay between the hard-core repulsion and the persistence of the motion leads to complex alignment modes. For instance, only 10% of the binary collisions correspond to an effective ferromagnetic alignment. Yet, we have observed spontaneous collective motion inside the system characterized by giant fluctuations of density. These results reveal the robustness of the polar order observed in theoretical and numerical models of 2D polar active matter on substrate.
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https://tel.archives-ouvertes.fr/tel-00567513
Contributor : Julien Deseigne <>
Submitted on : Monday, February 21, 2011 - 1:42:38 PM
Last modification on : Monday, February 10, 2020 - 6:12:21 PM

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  • HAL Id : tel-00567513, version 1

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Julien Deseigne. Système expérimental modèle d'un fluide actif polaire. Analyse de données, Statistiques et Probabilités [physics.data-an]. Université Paris-Diderot - Paris VII, 2010. Français. ⟨NNT : TS (2010) 160⟩. ⟨tel-00567513⟩

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