Experimental investigation of a nonspherical water droplet falling in air
Meenu Agrawal, Rajat Kumar Katiyar, Badarinath Karri, Kirti Chandra Sahu
Abstract
We experimentally investigate the shape oscillations of an initially nonspherical water droplet falling in air using high-speed imaging. We design a customized experimental setup that allows us to study the freely falling droplets of initially oblate/prolate/tilted configurations. The setup uses a pneumatic piston-cylinder arrangement and a superhydrophobically coated plate to propel a droplet upwards in air whose motion is then recorded using a high-speed camera. Due to the propulsive force imparted to the droplet, it undergoes oblate–prolate oscillations and eventually comes to rest at a maximum height, at which time the droplet has a zero vertical velocity and a nonspherical shape with an inclination to the horizontal. We study the effect of the initial aspect ratio and size of the droplet on its shape oscillations during its downward motion.