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VERSION:2.0
PRODID:-//Memento EPFL//
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SUMMARY:Instability of the flow above a rotating disk
DTSTART:20170131T141500
DTEND:20170131T151500
DTSTAMP:20260510T165109Z
UID:8972d811f2de0fdc0515e292d9eff4d10d23fdd2abf251c3c696694f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Eunok Yim\nThe rotating disk is an important classical problem
 \, due to the similarities between the 3D boundary layers on a disk and a 
 swept aircraft wing. It is nowadays admitted that a direct transition to t
 urbulence may exist through a steep-fronted nonlinear global mode located 
 at the boundary between the locally connectively and absolutely unstable r
 egions (Lingwood 1995\, 1997\; Pier 2003\; Viaud et al. 2008\, 2011\; Imay
 ama et al. 2014). However\, recent studies (Healey 2010\; Harris et al. 20
 12\; Imayama et al. 2013) suggest that there may be an alternative route s
 tarting at lower critical Reynolds number\, based on convective travelling
  waves but this scenario is still not fully validated and proven.\n \nTo 
 better characterize such transition\, direct numerical simulations are per
 formed in a closed cylindrical rotor-stator cavity (without hub) up to Re~
 105. All boundaries are no slip and for the stable region around the rotat
 ion axis prevents the disturbances coming from the very unstable stator bo
 undary to disturb the rotor boundary layer. Different transition scenarii 
 to turbulence are investigated when the rotor boundary layer is forced at 
 different positions and forcing amplitude. The associated dynamics of cohe
 rent structures in various flow regions are also investigated when increas
 ing Re. Finally\, the linear global stability of the mean-flow is investig
 ated in order to characterize the location of the front and compare to the
  previous local stability analyses of a single disk.
LOCATION:ME D2 2423 https://plan.epfl.ch/theme/generalite_thm_v2?request_l
 ocale=en&room=ME%20D2%202423&domain=places&dim_floor=2&lang=en&dim_lang=en
 &tree_groups=centres_nevralgiques%2Cacces%2Cmobilite_reduite%2Censeignem
STATUS:CONFIRMED
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