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SUMMARY:Viscoplastic Droplets - Maziyar Jalaal\, DAMTP
DTSTART:20191111T130000Z
DTEND:20191111T140000Z
UID:TALK133045@talks.cam.ac.uk
CONTACT:Prof. Jerome Neufeld
DESCRIPTION:Viscoplastic or yield stress materials can behave like solids 
 or fluids. Such materials\, if not sufficiently stressed\, behave like an 
 elastic solid\, but once the stress exceeds a critical value (the yield st
 ress)\, the material deforms like a viscous fluid (typically with a nonlin
 ear viscosity).\n\nWe will discuss the effect of the yield stress on sprea
 ding droplets. We use experiments\, asymptotic solutions\, and numerical s
 imulations to explain the dynamics and final shape of the droplets. Later\
 , we will show how one can externally control the shape of a spreading dro
 plet\, using temperature. For that\, we will first present the rheological
  properties of a thermo-responsive material that undergoes sol(Newtonian)-
 gel(yield stress) transition upon heating.  Then\, we show the final diame
 ter of a thermo-responsive droplet can be controlled by simply changing th
 e surface temperature. In the same part\, we introduce an experimental met
 hod based on optical coherence tomography to identify the solidified regio
 n inside a droplet.\n\nEventually\, we will briefly discuss the other appl
 ications of viscoplastic droplets.
LOCATION:MR5\, Centre for Mathematical Sciences
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