CAREER: Unraveling flow-fluid coupling during impact of complex fluid droplets

About This Grant

The impact of a droplet on a surface is common in nature and industry, ranging from raindrops landing on the ocean or soil to spray coating. In industrial applications, the droplets often contain particles, which can modify the fluid properties and lead to peculiar behavior upon impact. The dynamics of droplet impact have been studied extensively for simple liquid drops, but it has not been studied as extensively for droplets composed of complicated fluids such as a suspension of particles. Droplet impact for these systems is difficult to predict because it depends on the interplay of multiple effects such as surface tension, viscosity, and inertia. As a result, the flow fields in these systems can be complex, and particles inside the drop may not be evenly distributed throughout the drop. If the concentration of particles in the drop is high, the drop is opaque, which makes it difficult to visualize internal flows. This project will establish a framework that combines several state-of-the-art diagnostic methods to probe the impact dynamics of drops composed of complicated fluids. Data will provide critical insight into the impact dynamics of complex fluid droplets on surfaces. The project will support an educational plan for K-12, undergraduate, and graduate students to help build the STEM workforce pipeline and engage public interest in multiphase flow research through the art of science competitions. The goal of this award is to develop an experimental platform by synergistically combining various advanced diagnostic techniques to probe the detailed dynamics as complex fluids droplets impact on surfaces, and to generate systematic understanding of the coupling between the complex fluid properties and flow behavior. The spatially and temporally varying flow, stress, and particle concentration fields will be resolved and analyzed to determine their contributions to global and local dynamics, such as impact outcome, cavity dynamics, and jamming behavior. The insight will help build models to predict behavior and will provide pathways to optimize existing industrial practices. The experimental and analytical tools that will be developed for the proposed project could be applied to a broad range of complex fluid and multiphase systems beyond droplet impact. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.