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SUMMARY:Arrested bubble 'rise' in a narrow tube - Mrs Catherine Kamal\, Br
 istol
DTSTART:20170202T113000Z
DTEND:20170202T123000Z
UID:TALK69558@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:A long air bubble placed inside a vertical tube closed at the 
 top rises by displacing the fluid above it. Bretherton\, however\, found t
 hat if the tube radius\,  is smaller than a critical value there is no so
 lution corresponding to steady rise. We explain this finding by studying t
 he unsteady bubble motion for tube radius less than this critical value. W
 e show the minimum spacing between the bubble and the tube goes to zero in
  infinite time. This leads to a rapid slow-down of the bubble's mean speed
  proportional to the inverse-square of time giving the appearance of arres
 ted motion. What may seem surprising is that this mean speed is negative: 
 the bubble moves down rather than up. We explain this observation by the b
 ubble's expansion to the walls of the tube\, pushing fluid in the directio
 n opposite to gravity. Joint work with Jens Eggers
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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