BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:Sensitivity analysis and control of the wake behind a cylinder
DTSTART:20110615T113000
DTSTAMP:20260925T123747Z
UID:6db44f52c8db531a471094b5ca50e5119d62a7772a72a280c2fcf63d
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Simone Camarri\nMany studies have been dedicated to underst
 and the behavior of the wake behind a circular cylinder\, considered as a 
 paradigmatic bluff body flow\, and many of them focus on the primary and s
 econdary instabilities. In this respect\, sensitivity analyses based on ad
 joint methods have been widely applied to investigate the primary instabil
 ity of the wake. In particular\, the structural sensitivity analysis of th
 e linear stability problem has shed light on the process which gives rise 
 to a self-sustained global mode in the wake\,localizing the instability me
 chanism in two lobes symmetrically placed on the boundaries of the recircu
 lation bubble behind the cylinder [Giannetti & Luchini\, JFM 581 (2007)]. 
 More recently [Maquet et al.\, JFM 615 (2008)]\, additional information ha
 s been added by the sensitivity analysis of the primary instability with r
 espect to modifications of the base flow\, caused by the introduction of a
  localized steady force. This analysis suggests also passive control strat
 egies of the instability itself.  In this seminar\, a work will be concise
 ly presented which generalizes the previously mentioned analysis to the se
 condary instability of the cylinder wake (three-dimensional instability of
  the wake)\, i.e. to the case of a globally unstable base flow which is al
 so periodic in time. It will be shown that the structural sensitivity anal
 ysis of the associated linear problem allows\, in this case too\, the loca
 lization of the core of the 3D instability\, which is even more concentrat
 ed in the near wake with respect to the case of the primary instability. T
 he sensitivity of the 3D instability to a base flow modification\, obtaine
 d by the application of a localized steady force\,is also investigated and
  results will be shown.If allowed by the remaining time\, a strategy to de
 sign a feedback control of the vortex shedding instability based on the se
 nsitivity analysis of the instability itself will be also presented. The p
 roposed control design strategy assumes that realistic sensors and actuato
 rs are available for the controller\; results of its application to the fl
 ow behind a confined square cylinder will be shown.
LOCATION:GR C0 01 
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR