Nonrotationally symmetrical droplet on nylon fiber

Droplet condensation and evaporation is a fundamental problem in many applications of fibrous materials including fiber filters, water harvesting, and functional clothing. Compared with the droplets on flat surfaces, it is more complex to mathematically describe the profile of droplets on fibers because of two reasons. One is two oppositely signed arcs of curvature co-exist at the contact line between the droplet and the fiber. The other one is droplet on fiber is generally non-rotationally symmetrical. So far, there is still no method to determine the gravity of non-rotationally symmetrical droplet on fiber. The problem of the supporting force to balance the gravity of droplet is also difficult to solve. In this work, shape change of droplets hanging from a horizontal fiber with respect to its weight is investigated experimentally. Based on several empirical expressions obtained by fitting experimental data, the gravity of droplet is calculated under different volume. To get the support force, a theoretical model is proposed. The predicted support force from the model has an excellent agreement with the gravity of droplet from experiment.