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SUMMARY:Self-excited motions of volatile drops on swellable sheets - Dr Ad
 iti Chakrabarti\, School of Engineering and Applied Sciences\, Harvard Uni
 versity
DTSTART:20200501T140000Z
DTEND:20200501T153000Z
UID:TALK141883@talks.cam.ac.uk
CONTACT:Hilde Hambro
DESCRIPTION:I will demonstrate a new type of dynamical instability where a
  volatile droplet\, when deposited on a floating swellable sheet\, becomes
  asymmetric\, lobed\, and mobile. This phenomenon involves non-equilibrium
  swelling\, evaporation and motion\, working together to realize a self-ex
 citable spatially extended oscillator. Solvent penetration from the drople
 t causes the film to swell locally and eventually buckle\, changing shape 
 and the drop responds by moving. Simultaneously\, solvent evaporation from
  the swollen film causes it to regain its shape once the droplet has moved
  away. The process repeats and leads to complex pulsatile spinning and/or 
 sliding movements. I will show a one-dimensional experiment that highlight
 s the coupled dynamics of slow swelling of and evaporation from the film a
 nd the fast motion of the drop\, a characteristic of excitable systems. Fi
 nally\, I will provide a phase diagram for droplet excitability as a funct
 ion of drop size and film thickness and scaling laws for the motions of th
 e droplet.
LOCATION:Online
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