Cavity Measurement Inside Water Droplet on Superhydrophobic Surface

In this study, we show the dynamic of water droplets on the Superhydrophobic surface at low impact velocity. when the drop hits the surface, oscillation starts and the capillary waves formed a cylindrical cavity inside the drop and the cavity starts closing in a self-similar way until collapsing. We show that during receding the cavity collapses in different scenarios based on the impact velocity and the surface wettability. More importantly, observing for the first time high-speed (up to 5 million fps) visual records and considering optical distortion correction of the collapsing cavity. The experiment results of the cavity radius are compared with the modified Rayleigh-Plesset equation for free cylindrical flow and good agreement is shown.