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Home page > Séminaires > Archives séminaires > Séminaires 2020 > Visio-Séminaire MSC. 11 Mai 2020. Adrian Daerr (MSC) : "The charmed string : self-supporting loops through air drag".

Visio-Séminaire MSC. 11 Mai 2020. Adrian Daerr (MSC) : "The charmed string : self-supporting loops through air drag"

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


Video Seminar. Monday 11th May 14h00 Contact Michael Berhanu to attend the video seminar.

"The charmed string : self-supporting loops through air drag "

Pr. Adrian Daerr Laboratoire Matière et Systèmes Complexes, UMR 7057, Université de Paris

Abstract : The `string shooter’ experiment uses counter-rotating pulleys to propel a closed string forward (For a video, see [*]). In its steady state, the loop exhibits a transition from a gravity-dominated regime at low velocity towards a high-velocity regime where the string takes the form of a self-supporting loop [*]. I will show that this transition cannot be explained by inertial effects alone, but depends on the hydrodynamic drag exerted by the surrounding fluid, namely air. The string loop presents a critical point in its lifted state, analogous to a hydraulic jump, separating a supercritical zone where the wave velocity is smaller than the rope velocity, from a subcritical zone where waves propagate faster than the rope velocity. This critical point is also a geometrically singular point both in experiment and theory. I will discuss potential regularisation mechanisms of the string dynamics in the vicinity of this singularity.

[*] For a video of the experiment, see https://www.youtube.com/watch?v=rff...

Ref : http://dx.doi.org/10.1017/jfm.2019.631


Contact : Équipe séminaires / Seminar team - Published on / Publié le 11 mai 2020


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