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25 September 2017: One event

  • Invited Talks

    Monday 25 September 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

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