Study of passive and active driven motion of droplets on engineered substrates
dc.contributor.advisor
Sefiane, Khellil
dc.contributor.advisor
Valluri, Prashant
dc.contributor.author
Zhao, Hongyu
dc.date.accessioned
2022-05-02T14:45:38Z
dc.date.available
2022-05-02T14:45:38Z
dc.date.issued
2022
dc.description.abstract
Droplet motion is an everyday phenomenon with potential benefits to multiple
industrial and biological applications. It can be achieved via various methods,
and the understanding and altering of the underlying mechanism are
important to the accurate control of the droplet behaviour and motion. This
thesis focuses on three different mechanisms that induce the droplet motion:
roughness gradient by micro-structure fabrication, thermocapillary motion
with self-rewetting fluid and vapor-mediated droplet motion.
Firstly, the motion of microscale water droplets on the hydrophobic microstructured
surfaces with structural wettability contrast has been studied. The
velocity and displacement of the droplets moving across the wettability
contrasts have been monitored and their relations to the morphological
parameters of the micro-structure have been systematically investigated.
Besides, the dynamic behaviour of the droplets has been investigated and
explained by the mathematical mode proposed.
Secondly, the thermocapillary motion of self-rewetting droplets has been
reported. The behaviour of self-rewetting droplets departed greatly from the
droplets of ordinary mixture and pure fluids. A unique oscillatory behaviour
was observed for self-rewetting droplets, which was related to the nonmonotonic
dependence of surface tension on temperature. Influencing
parameters were studied and IR thermography assisted to reveal the internal
convection.
Last, the motion of sessile mixture or pure droplets induced by vapour was
investigated. The spatial concentration change via the mass transfer through
the liquid-vapour interface near contact line leads to unbalanced surface
tension, which leads to droplet motion. Depending on the concentration of
both droplets and the vapour, repulsive or attractive motion can be observed.
A phase map as well as a critical concentration boundary was proposed for
the mixture of PG and water droplets, which can help to predict the direction
of droplet motion.
en
dc.identifier.uri
https://hdl.handle.net/1842/38926
dc.identifier.uri
http://dx.doi.org/10.7488/era/2178
dc.language.iso
en
en
dc.publisher
The University of Edinburgh
en
dc.subject
Droplet
en
dc.subject
Surface science
en
dc.title
Study of passive and active driven motion of droplets on engineered substrates
en
dc.title.alternative
A study of passive and active driven motion of droplets on engineered substrates
en
dc.type
Thesis or Dissertation
en
dc.type.qualificationlevel
Doctoral
en
dc.type.qualificationname
PhD Doctor of Philosophy
en
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