Observation and modeling of droplet shape on metal fiber with gravity effect

Abstract

Droplet retention on metal fibers is a common physical phenomenon, and its drainage is significantly affected by the droplet shape. The purpose of this study is to experimentally investigate the effect of gravity on the shape of droplet on a metal fiber, and to present a method to quantitatively describe the droplet shape. It is found that droplets on a metal fiber are in the shape of clam-shell, and the droplet profile curves from the front view and the side view are both approximate to ellipse arcs or circle arcs. This finding inspires the description method of the droplet shape, covering the solid-liquid interface and the gas-liquid interface. In this method, the solid-liquid interface is described by a cylindrical function with the triple contact line as the boundary, and the triple contact line is expressed as the intersection line of two cylindrical surfaces; the gas-liquid interface is simplified as the curved surface formed by the profile curve revolving around the vertical axis, and the profile curve at an arbitrary azimuthal angle is described by the ellipse function with the variable semi-axis. The proposed model is validated by the experiments and the results show that, the goodness of fit of the predicted profiles is larger than 88%, and fthe deviations between the predicted volume and the experimental volume are within 10%.