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Accueil du site > Évènements > Séminaires > Séminaires LMA > Archives LMA > 2019

Mardi 10 Septembre 2019 / LMA

publié le

Séminaire LMA

Slow-sound analogues of black holes and laser effect in lined flow ducts

Orateur : Antonin Coutant, LAUM

Abstract : Using metamaterial impedance (liner) on the walls of a waveguide offers various possibilities to control and manipulate sound waves. In particular, it is possible to lower the local speed of sound. When adding a mean ow with velocity U larger than the effective speed of sound Ceff , supersonic regimes can be reached at low Mach numbers U/Co. By trapping the waves in a certain region of space, one can realize acoustic analogues of black hole. We will discuss a particular configuration of a double transition subsonic/supersonic flow that displays the analogue of the "black hole laser" effect. Due to the presence of negative energy waves, the ow can provide gain for the acoustic propagation, which leads to a whistling phenomenon at very low frequency.

Reference : A. Coutant, Y. Aurégan, V. Pagneux, "Slow sound laser in lined flow ducts" (2019)

Date et lieu : le mardi 10 septembre 2019 à 11h00, amphithéâtre du LMA

Voir en ligne : la page personnelle de l’orateur