Autonomous transport and splitting of a droplet on an open surface

Abstract

We show a standalone power-free technique for transporting and splitting a droplet on an open surface using continuous wettability-gradients. A three-dimensional phase-field Cahn-Hilliard model for interfaces and Navier-Stokes equations for transport are employed and solved numerically using the finite element method. We can control the droplet splitting ratio by manipulating the widths of the Y-branches. The physics of the droplet transport, flow pattern inside the droplet, and the splitting mechanisms have been explained through detailed numerical studies and scaling analysis.