Coalescence-induced propulsion of droplets on a superhydrophilic wire

Droplet transport on a cylindrical wire has applications in numerous fields such as fog collection, mist elimination, filtration, and oil/water separation. This work reports a droplet transport phenomenon on a superhydrophilic wire that shows a transient velocity powered not by the gradient of substrate geometry or wettability but primarily by the surface-to-kinetic energy transition that occurs along the axial direction upon coalescence. The transition efficiency is mainly limited by the viscous friction at the local liquid wedge, a relationship that a modified Ohnesorge number can capture.

Automated summary

This study reports a droplet transport phenomenon on a superhydrophilic wire, where the velocity is not driven by substrate geometry or wettability gradients, but primarily by surface-to-kinetic energy transition. The efficiency of this transition is mainly limited by the viscous friction at the local liquid wedge, which can be captured by a modified Ohnesorge number.