Droplet interactions with functional surfaces play a crucial role in many important physical processes, from preventing virus laden droplets passing through face masks to reducing the build-up of ice on the surfaces of flying aircraft. This project will investigate droplet impacts and droplet spreading on designed and functionally engineered surfaces. Theoretical multiphase fluid dynamics and mathematical modelling will be used to analyse droplet impacts, splashing, spreading, rebounding and droplet infiltration. Focus will be given to surfaces which are either permeable or heated.
For permeable surfaces, wettability, shape and liquid properties that either promote or limit liquid infiltration into the media below a droplet impact site will be analysed. This is relevant for the design of droplet repellent surfaces and coatings. Understanding how droplets interact with porous media below a permeable surface is also important to mitigate excessive pesticide spraying on crops and to control soil erosion, while also being of use when designing improved remediation strategies for chemical spills and contaminants. Models involving a range of initial contact angles, permeabilities and subsurface fluid flows will be investigated to determine how they impact the droplet shape as it is absorbed. The inverse problem of determining properties of the porous medium from the droplet behaviour will also be considered, with the aim of determining whether readily measured droplet properties on the surface can be used as proxies for sub-surface flow characteristics.
For heated surfaces, we wish to investigate and provide theoretical predictions for the onset of Leidenfrost behaviour (when a droplet skates above the surface on a thin layer of vapour, rather than directly resting on the surface). In spray cooling, if Leidenfrost behaviour occurs, then there is a drop in the heat transfer out of the solid that risks the longevity of the object being cooled, as the liquid and solid are no longer in direct contact. To enhance the effectiveness of spray cooling, surface shapes which can delay the onset of the formation of the vapour cushion between droplet and surface will be investigated, as well as other surface shapes that can cause Leidenfrost droplets to move across the surface.
The common theme across the project will be the development of theoretical and numerical models to analyse the droplet behaviour, focussing on the free-surface evolution and other key parameters such as the load on, and the infiltration through the surface. The numerical methods will be based on the boundary integral technique, with novel interface conditions coupling the droplet to reduced order models of liquid flow in the porous substrate, the gas surrounding the droplet and the temperature.
The successful candidate will interact regularly with members of the Fluid Mechanics Research Group in the School of Engineering: https://www.abdn.ac.uk/engineering/research/environmental-industrial-fluid-mechanics-122.php . Members of the Group use different combinations of numerical simulations, theoretical analysis, laboratory experiments and field measurements, to study physical processes associated with a wide range of applications, including droplet dynamics, groundwater remediation, geological CO2 storage, and coastal erosion.
Selection will be made on the basis of academic merit. The successful candidate should have, or expect to obtain, a UK Honours degree at 2.1 or above (or equivalent) in Engineering, Applied Mathematics, Physics, Computer Science or Chemistry.
Knowledge of fluid mechanics, familiarity with MATLAB, previous laboratory experience.
Experience of fluid dynamics and the use of numerical methods to solve differential equation would be valuable. Experience using Matlab would also be beneficial.
This project could be completed by a distance learning student.
Formal applications can be completed online: https://www.abdn.ac.uk/pgap/login.php
• Apply for Degree of Doctor of Philosophy in Engineering
• State name of the lead supervisor as the Name of Proposed Supervisor
• State ‘Self-funded’ as Intended Source of Funding
• State the exact project title on the application form
When applying please ensure all required documents are attached:
• All degree certificates and transcripts (Undergraduate AND Postgraduate MSc-officially translated into English where necessary)
• Detailed CV, Personal Statement/Motivation Letter and Intended source of funding
Informal inquiries can be made to Dr P Hicks (firstname.lastname@example.org) with a copy of your curriculum vitae and cover letter. All general enquiries should be directed to the Postgraduate Research School (email@example.com)