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2 octobre 2018: 1 événement

  • Séminaires Invités

    Mardi 2 octobre 11:00-12:30 - Sébastien Manneville - Laboratoire de Physique, Ecole Normale Supérieure de Lyon

    Soft Matter under Ultrasound : From Flow Imaging to Structural Changes

    Résumé : Ultrasound is commonly used in medicine both at low intensity for diagnosis (echography) and at high intensity for therapy (lithotripsy or tumour treatment). The goal of this talk is to show that these two sides of ultrasound may also provide key fundamental insights into the mechanical behaviour of soft condensed matter. First, we have developed an ultrafast ultrasonic imaging setup that provides access to the local deformation and velocity fields in complex fluids and soft solids under simple shear. This technique will be illustrated on the example of instabilities in a dense suspension of cornstarch grains [1]. Second, I will show that ultrasound can also be used in the high-power regime to interact with the structure of a soft material. Indeed, it is well known that ultrasound generates acoustic radiation forces when impacting on a solid boundary. We build upon this property to (i) fluidise locally a wet granular packing [2] and (ii) study the effect of low-frequency ultrasound on the viscoelastic behaviour of a colloidal gel.
    [1] Saint-Michel B., T. Gibaud, S. Manneville, Uncovering instabilities in the spatiotemporal dynamics of a shear-thickening cornstarch suspension, Physical Review X 8, 031006 (2018)
    [2] Lidon P., N. Taberlet, S. Manneville, Grains unchained : local fluidization of a granular packing by focused ultrasound, Soft Matter 12, 2315-2322 (2016)

    contact : Romain Mari

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

    En savoir plus : Séminaires Invités