Water droplet motion on an inclining surface

Abstract

Droplet motion induced by external forces such as mechanical vibrations, shear flows or gravitational forces has a major importance in many industrial applications. The present study introduces a setup for a tilting plane experiment, which enables investigations of the droplet behaviour due to the balance between surface tension and gravitational force. Furthermore, droplet motion measurements on a tilting acrylic glass surface are presented. The main aspect of this study is the influence of the droplet volume and the angular velocity of the inclining plane on the droplet detachment. To quantify this influence, different moving regimes are detected and specified. Further, flow maps due to the rotational velocity are obtained. The results show that the inclination angle needed to initiate drop motions decreases when the droplet volume increases. In addition to that, the droplet motion is initiated at a smaller inclination angle if the angular velocity decreases. This behaviour has no influence when rotational velocity increases above a certain threshold. The study concludes that the detachment of water droplets on a tilting acrylic surface can be forced and amplified if either the droplet volume is increased or the angular velocity of the surface is decreased.