A. Schwarzwälder, J. Meyer, A. Dittler

Physics of Fluids, 2024, 36, 012010, https://doi.org/10.1063/5.0178183

In this study, the dynamics of a single water droplet on a mechanically excited single fiber are investigated fundamentally. By utilizing state-of-the-art high-speed camera technology, the droplet’s motion is captured with exceptional temporal resolution, enabling a detailed analysis of its position, size, and kinetics. We can identify distinct motion patterns of a droplet adhering to the fiber, which can exhibit either a static, a tilting, or swinging motion. The swinging and tilting motion can be overlaid with a higher-frequency deformation in response to the fiber excitation. Additionally, we examine the detachment of the droplet from the fiber as well as for the first time the (periodic) reattachment resulting from the mechanical excitation. The used droplet volumes are smaller, and the excitation shown here is greater than the excitation acceleration previously investigated in single fiber studies. Insights into droplet–fiber interactions can provide a better understanding of the mechanisms occurring in coalescence filters in harsh environments, which cannot be observed in situ with high temporal and spacial resolution in a full-scale filter due to the lack of optical access.