This project forms part of my Open Fellowship grant, which you can read more about here.
Background
When a droplet meets a hot surface, it can levitate on a cushion of its own vapour — the spectacular Leidenfrost effect. In some contexts, the vapour film is useful, allowing droplets to skate and transport themselves without contact. In others, it is dangerous: if hot reactor rods in a nuclear plant become wrapped in stable vapour films, emergency cooling is prevented.
Despite much observation, we still lack predictive models for when vapour films form, how long they survive, and how they collapse. Conventional fluid dynamics fails here, because the films that control stability can be just tens of nanometres thick, and their behaviour is dictated by non-classical gas and heat transfer effects.
Objectives
- Develop predictive mathematical models for the formation and stability of vapour films beneath hot droplets.
- Determine the conditions that trigger collapse or stabilisation of the film, including the role of nanoscale thermal transport.
- Explore strategies for controlling the Leidenfrost effect — enhancing it for applications like mobile “lab-on-a-drop” reactors, or suppressing it for efficient cooling in safety-critical environments.
Approach
The project combines modelling and simulation at multiple scales:
- Extend lubrication-type models to incorporate gas kinetic and thermal effects in nanoscale vapour films.
- Perform simulations of droplet impact and levitation across a range of surface temperatures and surface designs.
- Work with experimental partners to validate predictions and test engineered surfaces designed to either promote or suppress the Leidenfrost state.
Collaborators
- Detlef Lohse (Twente) – world-leading experiments on Leidenfrost drops and vapour films.
- Industrial/engineering partners – interested in cooling, energy efficiency, and nuclear safety.
What’s Involved
The researcher will develop expertise in modelling nanoscale vapour films, advanced simulation of non-isothermal multiphase flows, and the physics of heat and mass transfer at interfaces. They will collaborate internationally, with opportunities to visit experimental labs and compare their predictions with state-of-the-art measurements. The project also offers scope for personal and professional development, including funded opportunities to organise thematic workshops and engage with a broad scientific and engineering community.
James Sprittles 