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SUMMARY:Horizontal film drainage: soap film elasticity\, lubrication equat
 ion\, line tension and instability  - Isabelle Cantat\, U. Rennes
DTSTART:20230210T160000Z
DTEND:20230210T170000Z
UID:TALK195028@talks.cam.ac.uk
CONTACT:Prof. Jerome Neufeld
DESCRIPTION:The thinning of the liquid films separating bubbles in a foam 
 or in a bubbly liquid controls the coalescence process and the foam stabil
 ity\, and is highly relevant in many\nindustrial processes. The spatiotemp
 oral evolution of the film thickness is governed by highly nonlinear equat
 ions\, whose solutions are still mostly unknown. For a flat horizontal  fi
 lm in contact with a meniscus at a lower pressure\, a classical theoretica
 l solution is the appearance\, deepening and widening of a pinched region\
 , close to the meniscus and invariant by translation along the meniscus.\n
 We show experimentally that this theoretical film thickness profile is uns
 table\, and we measure the instability wavelength along the meniscus.\n\nT
 his initial instability triggers the so called "marginal regeneration". Th
 is peculiar hydrodynamic instability is at the origin of the thinner patch
 es produced at the bottom of vertical soap films and slowly rising to the 
 top. In our horizontal film\, as the gravity-induced rising motion of the 
 patches is suppressed\, we are able to study its long time dynamics\, in a
  well controlled situation. The predictions made by Mysels et al. in 1959 
 are successfully tested on our data and are extended by an original coarse
 ning model. 
LOCATION:MR2\, Centre for Mathematical Sciences\, Wilberforce Road\, Cambr
 idge
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