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TZID:Europe/Paris
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BEGIN:VEVENT
UID:0-664@lptms.universite-paris-saclay.fr
DTSTART:20190514T110000Z
DTEND:20190514T120000Z
DTSTAMP:20190507T101651Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
s-thibault-congy/
SUMMARY:Séminaire du LPTMS: Thibault Congy - LPTMS\, salle 201\, 2ème ét
age\, Bât 100\, Campus d'Orsay - 14 Mai 19 11:00
DESCRIPTION:Wave-mean flow interactions in dispersive hydrodynamics\nThibau
lt Congy (Department of Mathematics\, Physics and Electrical Engineering\,
Northumbria University\, Newcastle upon Tyne\, UK)\nThe interaction of wa
ves with a mean flow is a fundamental and longstanding problem in fluid me
chanics. The key to the study of such an interaction is the scale separati
on\, whereby the length and time scales of the waves are much shorter than
those of the mean flow. The wave-mean flow interaction has been extensive
ly studied for the cases when the mean flow is prescribed externally—as
a stationary or time-dependent current (a "potential barrier").\n\nIn this
talk\, I will describe a new type of the wave-mean flow interactions wher
eby a short-scale linear wave is incident on a evolving large-scale nonlin
ear dispersive hydrodynamic state: a rarefaction wave or a dispersive shoc
k wave (DSW). Modulation equations are derived for the coupling between th
e wavepacket and the mean flow in the nonlinear dispersive hydrodynamic st
ate. These equations admit particular classes of solutions that describe t
he transmission or trapping of the linear wave by an unsteady hydrodynamic
state. Two adiabatic invariants of motion are identified in both cases th
at determine the transmission\, trapping conditions and show that wavepack
ets incident upon smooth expansion waves or compressive\, rapidly oscillat
ing DSWs exhibit so-called hydrodynamic reciprocity.\n\nThe developed theo
ry is general and can be applied to a broad class of nonlinear dispersive
wave equations in various physical contexts including nonlinear optics and
cold atom physics. The Korteweg-de Vries equation will be considered as a
concrete example. This is joint work with Gennady El and Mark Hoefer\, an
d the talk is based on Ref. [1].\n\n[1] T. Congy\, G. A. El and M. A. Hoef
er\, Interaction of linear modulated waves with unsteady dispersive hydrod
ynamic states\, arXiv:1812.06593.
CATEGORIES:seminars
LOCATION:LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay\, 15
Rue Georges Clemenceau\, Orsay\, 91405\, France
GEO:48.698185;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
Orsay\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS\, salle 201\, 2è
me étage\, Bât 100\, Campus d'Orsay:geo:48.698185,2.181768
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