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25 septembre 2017: 1 événement

  • Séminaires Invités

    Lundi 25 septembre 2017 14:00-15:30 - Blaise DELMOTTE - Courant Institute of Mathematical Sciences, New-York, USA

    Hydrodynamic Genesis of Colloidal Creatures

    Résumé : When colloidal particles are rotating adjacent to a nearby floor, strong advective flows are generated around them, even quite far away. When a group of these microrollers is driven, the strong hydrodynamic coupling between particles leads to formation of new structures. Our experimental observation shows that a suspension of microrollers undergoes a cascade of instabilities : an initially uniform front of microrollers evolves first into a shock-like structure, which then quickly becomes unstable, emitting fingers of a well-defined wavelength ; then the fingertips pinch off to form compact motile structures translating at high speed. These colloidal creatures are self-sustained and form a stable state of the system.
    Combining experiments, large scale numerical simulations and continuum models, I will detail the mechanisms involved in each step. I will demonstrate that the whole process is primarily controlled by a geometric parameter : the height of the particles above the floor. I will also explain the predominant role of hydrodynamic collective effects in the development of these colloidal creatures. To conclude, I will show how to use these creatures for particle transport and flow generation in confined environments.

    The talk will be given by video-conference

    contact : Philippe Peyla

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères

    En savoir plus : Séminaires Invités