Numerical simulation of droplet impacting on a microstructured surface: Geometry, wettability, and control of jump-off force

Droplet impacting on the solid substrate, which typically is a simple planar surface, has been extensively studied for various technological applications. Here, through numerical calculation, we explore the droplet impacting on a single hemispherical bead and double bead structures. Several key physical parameters have been taken into account, including the Weber number, wettability, and geometry of microstructures. We reveal the spatiotemporal evolution of the droplet pattern, the correlated physical parameters, and the underlying physical mechanisms (air cushion or bubble). These results provide theoretical guidance to control jump-off forces via the structure design and suitable wettability for the relevant applications such as erosion protection.