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UID:6650@i2m.univ-amu.fr
DTSTART;TZID=Europe/Paris:20201028T140000
DTEND;TZID=Europe/Paris:20201028T150000
DTSTAMP:20241120T201803Z
URL:https://www.i2m.univ-amu.fr/evenements/dynamical-analysis-of-the-unste
 ady-flow-phenomena-around-a-flapping-wing-chandan-bose/
SUMMARY:Chandan Bose (Department of Aerospace and Mechanical Engineering\, 
 University of Liège\, Belgium): Dynamical analysis of the unsteady flow p
 henomena around a flapping wing - Chandan Bose
DESCRIPTION:Chandan Bose: The present work deals with the transitional wake
  dynamics and nonlinear fluid-structure interaction behavior of flapping w
 ings in the low Reynolds number regime through high-fidelity\nnumerical si
 mulations. This talk is largely focused on identifying the dynamical trans
 ition routes to chaos in the unsteady flow-field of rigid and flexible fla
 pping wings and unraveling the underlying flow-physics behind the chaotic 
 transition. A quasi-periodic (QP) route is established in the near-field o
 f a pitching-plunging airfoil as the dynamic plunge velocity (kh)\, propor
 tionally the amplitude-based Strouhal number\, is gradually increased. Fur
 ther\, it is observed that the QP state gets interspersed with intermitten
 t bursts of aperiodicity preceding chaos. Following this\, the role of nea
 r-field vortex interactions in making the unsteady flow-field transition f
 rom periodicity to chaos is investigated. A dynamic interlinking of the ne
 ar and far-field wake transitions shows that the deflected jet undergoes a
  switching of direction at its far-end due to the propagation of the QP tr
 igger from the nearfield. Eventually\, this near-field QP state gets inter
 spersed with aperiodic bursts which trigger the direction flipping of the 
 immediate couple at the trailing-edge resulting in a full reversal of the 
 deflection direction of the wake. Finally\, the wake topology becomes chao
 tic through a series of rapid aperiodic jet-switching. A similar aperiodic
  transition is observed in the 3D flow-field beyond a considerably high va
 lue of kh. The underlying complex interactions among leading-edge\, traili
 ng-edge\, and tip vortices are analyzed in detail with the aid of Qcriteri
 on iso-surfaces. This study establishes that the transition to aperiodicit
 y in the wake of a flapping wing is indeed a physical phenomenon and not a
 n artefact of the 2D flow assumption. In order to understand the nonlinear
  FSI dynamics of flapping wings\, the flow-induced vibration of a 2-DOF pa
 ssively flapping airfoil is investigated at a low value of the structure-t
 o-fluid added mass ratio. This flexibly mounted flapping system is seen to
  undergo a chaotic transition through a Ruelle-Takens-Newhouse (RTN) route
 . Nonlinear time series analysis techniques have been implemented to chara
 cterize the different dynamical states present in the course of transition
  and to establish the associated transition route to chaos.\n&nbsp\;\n\nIO
 SSB Seminar
ATTACH;FMTTYPE=image/jpeg:https://www.i2m.univ-amu.fr/wp-content/uploads/2
 020/09/Chandan-Bose.jpg
CATEGORIES:Interdisciplinary online seminar series on Biolocomotion
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