Peter Lewin-Jones

PhD Title: Liquid drop impacts: when trapped gas nanofilms lead to bouncing

PhD Supervisors: James Sprittles and Duncan Lockerby

About Me:

I am currently an Early Career Fellow in the Warwick Institute of Advanced Study. I have recently been award my PhD from the HetSys CDT, after passing my viva in November 2024.

My PhD and ongoing research investigates the behaviour of the thin gas layer formed when a liquid droplet impacts onto a surface, such as another drop, a smooth solid or a bath of liquid. This problem contains physics beyond those captured by the classic Navier-Stokes equations of fluid dynamics, including van der Waals driven disjoining pressure and kinetic effects in the gas film. It is also fundamentally multi-scale, with the gas film thickness thousands of times smaller than the size of the drop.

I have developed a numerical model to predict when and how contact occurs during the impact of a drop. This modelling involves multi-scale numerical simulations using the finite element method. My research into head-on collisions between identical droplets, and when these drops will merge or bounce, has been published in the Journal of Fluid Mechanics. I compare to experimental data, predicting the critical impact speed at which the behaviour changes from bouncing to merging, and explore regimes beyond those that are currently accessible to experiments. For this article I am a finalist of the 2025 Lighthill Thwaites Prize.

I am currently working on the impact of drops onto liquid baths, and how the trapped gas film can cause bouncing rather than merging. This is a more complex problem, as during the impact the gas film becomes curved. I am working with Dan Harris and his group at Brown University, who are performing experiments to compare to my modelling. An article is currently in preparation.

I have also worked as part of two large collaborations during my PhD studies. The first looked into the early stages of drop coalescence, where we used a variety of experimental and computational techniques to investigate the moments before and after two drop merge. An article has been published in Physical Review Fluids. Separately to my work on droplets, I worked with a group of chemists and biologists on measuring the porosity of cell membranes, where I used mathematical modelling to understand the experiment technique being used. An article has been published in Communications Biology.

My undergraduate degree was at Mansfield College, University of Oxford. I initially studied Mathematics, specialising in fluid dynamics, numerical methods and mathematical physics. At the end of my third year I undertook a summer research project investigating large-scale structures in turbulent fluids. I then switched to Mathematical and Theoretical Physics for my Masters year, graduating with a first class MMathPhys degree. My masters thesis used self-consistent field theory to model polymer melts.

Email:

peter.lewin-jones@warwick.ac.uk