Background
A major open challenge in fluid dynamics is to predict what happens when two drops collide. The outcome — whether they bounce, merge, or fragment — is dictated by a trapped nanometre-thin film of gas or liquid. Standard computational fluid dynamics (CFD) packages, built on the Navier–Stokes–Fourier framework, cannot resolve these films and therefore fail to capture observed behaviours.
To address this, new computational methods are required that combine the physics of nanoscale films with the ability to follow three-dimensional, time-evolving interfaces. Embedding thin-film models into Volume-of-Fluid (VoF) solvers offers this opportunity: the thin-film model governs the approach to contact, while VoF naturally handles the post-contact dynamics, including coalescence, breakup, and fragmentation. This development will enable predictive simulations of drop collisions with direct relevance to end applications such as rainfall formation in clouds, efficiency of agricultural sprays, combustion in fuel injectors, and advanced coating and printing technologies.
Objectives
- Develop new numerical techniques that allow 3D VoF solvers to incorporate nanoscale lubrication models for thin films.
- Demonstrate predictive capability across a range of collision outcomes, including bouncing, merging, and fragmentation.
- Deliver open-source computational tools ready for extension to applications in clouds, sprays, energy systems, and advanced manufacturing.
Approach
The project will advance multiphase flow simulations by:
- Extending existing Volume-of-Fluid (VoF) solvers (e.g. Basilisk) to incorporate new nanofilm models derived from kinetic theory.
- Developing robust coupling strategies where lubrication models are applied in thin-film regions, seamlessly integrated into the full VoF framework.
- Performing large-scale computations of 3D droplet collisions, capturing both the approach-to-contact physics and the post-contact evolution of the merged or fragmented drops.
- Validating results against high-resolution experimental data from international partners.
Potential Collaborators
- Basilisk development community – expertise in VoF methods and multiphase simulations.
- Warwick Applied Mathematics & Engineering – groups specialising in numerical methods and turbulent multiphase flows.
- International partners (e.g. EPFL, Twente) – experimental data on droplet collisions and film dynamics for validation.
What’s Involved
The researcher will gain experience in cutting-edge multiphase simulation methods, from numerical model development to high-performance computing. They will learn how to embed nanoscale thin-film models into large-scale 3D VoF solvers, bridging physics across orders of magnitude in scale. The project is inherently interdisciplinary, offering opportunities to collaborate with applied mathematicians, experimentalists, and end-users in atmospheric science, agriculture, energy, and advanced technology sectors.
James Sprittles 