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SUMMARY:Weak nonlinearity for strong nonnormality
DTSTART:20220908T160000
DTEND:20220908T170000
DTSTAMP:20260501T071214Z
UID:9286aa57b88087bdce00e6b035106064c7e24d69735a9fb97afd5b0b
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. François Gallaire\, EPFL Lausanne\nAbstract: In this w
 ork with Y.-M. Ducimetière and E. Boujo\, we propose a theoretical approa
 ch to derive amplitude equations governing the weakly nonlinear evolution 
 of nonnormal dynamical systems when they experience transient growth or re
 spond to harmonic forcing. This approach reconciles the nonmodal nature of
  these growth mechanisms and the need for a center manifold to project the
  leading-order dynamics. Under the hypothesis of strong nonnormality\, we 
 take advantage of the fact that small operator perturbations suffice to ma
 ke the inverse resolvent and the inverse propagator singular\, which we en
 compass in a multiple-scale asymptotic expansion. The methodology is outli
 ned for a generic nonlinear dynamical system\, and several application cas
 es which highlight common nonnormal mechanisms in hydrodynamics: the strea
 mwise convective nonnormal amplification in the flow past a backward-facin
 g step\, and the Orr and lift-up mechanisms in the plane Poiseuille flow.
LOCATION:https://ethz.zoom.us/j/94817809233?pwd=N0pzbnQwSFFTQnVPcVR3SkNrd2
 9OQT09
STATUS:CONFIRMED
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