An experimental study of the effects of wind on spray droplets generated by raindrop impact onto water surface

Xinan Liu, University of Maryland College Park, College Park, MD, United States, Chang Liu, Ghent University, CAVELab - Computational and Applied Vegetation Ecology, Gent, Belgium and James H Duncan, University of Maryland College Park, Mechanical Engineering, College Park, MD, United States
The effects of wind on the generation of spray (secondary) droplets during the impact of single water drops on a water surface are studied experimentally in a wind tunnel that has a test section with a deep-water pool. Experiments are performed by varying impacting drop diameters ranging from 2.0 to 4.0 mm and wind speeds up to 10 m/s. Secondary droplets generated during drop impact are measured with a backlit, cinematic shadowgraph technique that employs a high-speed camera. Our experimental results show that after the drop hits the water surface an asymmetrical crown forms on the leeward side of the periphery of the colliding region while a wave swell forms on the windward side. The waves on the windward side of the drop impact are stronger than those on the leeward side. Secondary droplets are generated from the crown rim. The probability distributions of radii and velocities for the droplets in different experimental conditions are presented and discussed. It is found that the mass, momentum and energy fluxes of the secondary droplets drastically change with the wind speed.