Abstract
The rich literature on the impact of droplets on surfaces is dominated by studies of relatively accessible, microlitre droplets, predominantly motivated by the relevance to industrial processes such as inkjet printing. However, detailed analysis of the impact dynamics of picolitre aerosol droplets remains an under-researched field, mainly due to experimental challenges, despite their wide-ranging relevance. Here we provide a comprehensive experimental analysis of the impact dynamics of picolitre droplets at relatively low inertia (We ∼1.89–19.6), while varying viscosity (giving Oh ∼0.0168–0.0408) and surface wettability. A 30% increase in maximum contact diameter is seen across the We range, as well as a 10% increase as the impact surface changes from hydrophobic to hydrophilic. The surface wettability has an even more pronounced impact on the receding velocity and receding contact angle, whilst a non-linear relationship is observed between the receding velocity and We. Increasing Oh results in a 50% reduction in the receding velocity, along with 30% increase and decrease in the advancing and receding contact angles, respectively, with negligible impact on the maximum contact diameter. The measurements are compared with existing models (e.g., for larger droplets) and a more accurate relationship between the maximum spreading factor and We for picolitre aerosol droplets, which also incorporates the dependence on surface wettability, is derived.
Original language | English |
---|---|
Journal | Aerosol Science and Technology |
Early online date | 6 Jan 2025 |
DOIs | |
Publication status | Published - 6 Jan 2025 |
Data Availability Statement
Data are available at the University of Bristol data repository, data.bris, at https://doi.org/10.5523/bris.15hwdyu2yfsde2dep9i3nwqgk0.Acknowledgements
The authors would like to acknowledge Jonathan Reid for helpful discussion at the early stage of this researchFunding
L.K.M. acknowledges financial support from EPSRC (EP/ W022206/1).