CBET-EPSRC: Droplet Impact on Fluid Interfaces: 3D Effects Across Scales

Over the past several decades there has been persistent and broad interest in the elucidation of drop impact problems. In the present work, we propose an integrated experimental, numerical, and analytical investigation of droplet impact on fluid interfaces with a focus on three-dimensional effects. Arguably, the required algorithms and associated computing power needed to accurately investigate 3D impacts are only just starting to mature in recent years due to the highly multi-scale nature of the fluid flow and strongly non-linear interfacial deformations. Similarly, recent advances in visualization and flow measurement have now made such investigations possible in the lab. Our ambitious project brings together a diverse set of young leaders in fluid dynamics to tackle this exciting and pressing research topic, and develop new transformative frameworks to study this challenging set of problems with cutting-edge tools and methodologies.

Droplet-liquid impacts are fundamental to a range of industrial applications such as spray cooling, fuel injection, agricultural applications such as pesticide spray, and rain droplet impact, infectious disease transmission, manufacturing applications such as inkjet printing and droplet-based 3D printing, and environmental applications such as oil spill remediation. The bulk of prior work on droplet-liquid and droplet-solid impact focuses on axisymmetric, normal impacts due to the relative simplicity of experimental characterization and visualization and reduced computational demands. In practice, non-axisymmetric droplet-interface impacts are far more common and thus broadening the current understanding to include explicit three-dimensional effects is of critical and timely importance to unlocking and advancing applications. The objective in each constituent study will be focused on delineating parametric thresholds between the impact regimes of rebound, coalescence, and splashing. These efforts will be accompanied by the development of reduced-order models (guided and benchmarked by experiment and high-fidelity simulation) to extend the practical applicability of our results.

The highly collaborative research program proposed herein will fully span low-energy to high-energy impacts under a single framework and allow the development of a single, consistent, physical picture for droplet impacts on liquid layers of the same fluid, with an unprecedented focus on three-dimensional effects, the role of the ambient gas, and the depth of the fluid layer. The research outputs are anticipated not only to include the specific scientific discoveries, but also benchmarked and documented experimental and computational tools and datasets to strengthen the broad global research efforts in the area.

Moreover, the PIs will jointly develop new experimental and simulation data visualization activities related to the proposed work for the promotion of science, outreach purposes, and access initiatives in both the UK and USA. Several established artists have agreed to participate in visualisation of fluids events, open studio sessions and competitions, which will be organised by the PIs, building on their collective record of success in scientific visualisation.