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Accueil du site > Séminaires > Séminaires 2021 > MSC Visio-Seminar. May 17th 2021. Jean-Baptiste Gorce (MSC, Université de Paris) : "Dynamics of spinning discs in fluid".

MSC Visio-Seminar. May 17th 2021. Jean-Baptiste Gorce (MSC, Université de Paris) : "Dynamics of spinning discs in fluid"

Sauf mention contraire, les séminaires et les soutenances se déroulent à 11h30 en salle 454A du bâtiment Condorcet.

There will be a live diffusion with Zoom.

Monday May 17th 11h30.

Contact Michael Berhanu to attend the video seminar

Dynamics of spinning discs in fluid

Dr. Jean-Baptiste Gorce

Laboratoire Matière et Systèmes Complexes Université de Paris

Spinning bodies produce vortices and transfers angular momentum to surrounding fluids via a combination of viscous dissipation and inertial effects. When such spinning bodies acquire a velocity relative to the surrounding fluids, the coupling between the vortex and the flows affects their trajectory. The orbits depend on both the hydrodynamic instabilities generated by spinning bodies and the surrounding flow field. Here, I will present the dynamics of surface magnetic spinning discs in two different contexts.

I will first draw analogies between optical lattices and surface flows generated by two orthogonal standing waves, the vortex lattice. I will show that the surface flows analogous to optical lattices efficiently manipulate spinning discs at the liquid-gas interface. By changing the angular frequency of the disc or the wave amplitude, one can precisely control the disc’s orbit. Multiple discs with identical angular frequency self-organize into stable patterns within a vortex, while discs with different angular frequencies orbit with different radii. The results offer a powerful tool in scientific and engineering contexts. Adjacent vortices can confine chemical agents or biological populations, and spinning discs can carry them back and forth.

I will also report self-guided propulsion of magnetic fast-spinning discs on a liquid surface in the presence of a solid boundary. Above some critical angular frequency (higher rotational Reynolds numbers), such discs generate localized 3D vortices. An isolated spinning disc in an unbounded fluid performs chaotic motions while its motion becomes deterministic as the disc approaches a solid boundary. Such spinner-vortices are attracted and propagate along walls of any shape. The angular frequency of the disc controls the propulsion velocity and the distance to the wall. We calculate the wall repulsion force using tools of classical mechanics.

Contact : Équipe séminaires / Seminar team - Published on / Publié le 20 avril

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