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DTSTART:19700329T010000
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CATEGORIES:Engineering Fluids Group Seminar
SUMMARY:Bifurcations and control of propagating bubbles in
  Hele-Shaw channels - Dr. Alice Thompson (Universi
 ty of Manchester)
DTSTART;TZID=Europe/London:20220204T123000
DTEND;TZID=Europe/London:20220204T133000
UID:TALK166921AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/166921
DESCRIPTION:The propagation of a deformable air finger or bubb
 le into a fluid-filled channel with an imposed pre
 ssure gradient is a classical problem first studie
 d by Saffman and Taylor within the context of a de
 pth-averaged model. At zero surface tension\, fing
 ers of any width may exist\, but the inclusion of 
 vanishingly small surface tension selects symmetri
 c fingers of discrete finger widths. At finite sur
 face tension\, Vanden-Broeck later showed that oth
 er families of 'exotic' states exist\, but these s
 tates are all linearly unstable and cannot be obse
 rved directly in experiments.\n\nIn this talk\, I 
 will discuss the related problem of air bubble pro
 pagation into rigid channels with axially-uniform\
 , but non-rectangular\, cross-sections. By includi
 ng a centred constriction in the channel\, multipl
 e modes of propagation can be stabilised\, includi
 ng symmetric\, asymmetric and oscillatory states\,
  with a correspondingly rich bifurcation structure
 . These phenomena can be predicted via depth-avera
 ged modelling\, and also observed in our experimen
 ts\, with quantitative agreement between the two i
 n appropriate parameter regimes. This agreement pr
 ovides insight into the physical mechanisms underl
 ying the observed behaviour. I will outline our ef
 forts to understand how the system dynamics is aff
 ected by the presence of nearby unstable solution 
 branches acting as edge states. Finally\, I will d
 iscuss our recent work on how feedback control and
  control-based continuation could enable direct ex
 perimental observation of stable or unstable modes
 .
LOCATION:CUED\, LR3A
CONTACT:
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