Droplets on surfaces are of significant interest in many research fields from heat exchange to staining of materials and to transmission of viruses. When a droplet dries on a surface, materials within it are deposited due to internal flows within the droplet and may create a stain or a crystal pattern. The structure of this stain is dependent on the heat, momentum and the mass transport within the droplet during its evaporation. It is also dependent on the behavior of the three-phase contact line and the liquid contact with the surface. For a sessile droplet of salt solution, such as sodium chloride, it is usually assumed that at a relative humidity below around 75% (the deliquescence limit) salt crystallization will occur if the concentration of the droplet is above the saturation limit and the surface contains enough roughness to trigger heterogeneous crystallization.
In recent work we have shown that it is possible to create a surface smooth enough to halt heterogeneous crystallization and sessile droplets which are volumetrically stable even when the humidity well below the deliquescence limit. We also have preliminary evidence that these droplets can be forced to both shrink and grow by adjusting to the surrounding humidity. In this PhD you will study these stable droplets in controlled humidity and seek to understand the flows created by local concentration gradients within the droplet. You will also investigate the flow, and any deposition onto surfaces, when the droplets are both volumetrically stable and when they are condensing or evaporating.
It is expected that the applicant will have a good degree in Engineering or Physics with a good experimental background. We are particularly interested to hear from applicants with experience in surfaces, fluids and/or phase change.
The student will be part of the Wetting, Interfacial Sciences and Engineering Group within the Institute for Multiscale Thermofliuds. You will join a vibrant community of PhD students, postdoctoral research associates and academics working in various aspects of surfaces and wetting.
Further Information:
The University of Edinburgh is committed to equality of opportunity for all its staff and students, and promotes a culture of inclusivity. Please see details here: https://www.ed.ac.uk/equality-diversity
Closing Date:
Principal Supervisor:
Eligibility:
Minimum entry qualification - an Honours degree at 2:1 or above (or International equivalent) in a relevant science or engineering discipline, possibly supported by an MSc Degree. Further information on English language requirements for EU/Overseas applicants.
Funding:
Applications are welcomed from self-funded students, or students who are applying for scholarships from the University of Edinburgh or elsewhere
