Nanodroplets impact on surfaces decorated with ridges

The dynamics of droplets impacting on solid surfaces are directly related to a variety of engineering applications. As some industrial processes have been refined to the nanoscale, research interest in nanodroplets impact is growing. In this work, molecular dynamics (MD) is employed to investigate the impact processes of nanodroplets on superhydrophobic surfaces decorated with triangular nanoridges. We confirm that the decorated nanoridges can significantly promote the bouncing performance of nanodroplets, including enlarging the bounce domain, reducing the contact time, and enhancing the bounce velocity. We identify five distinct bounce modes for nanodroplets on the nanoridged surfaces, and the variation laws of contact time and bounce velocity of nanodroplets are determined by the characteristics of these bounce modes. Configuration of nanoridges can influence the variation laws of contact time and bounce velocity through changing the bounce modes of nanodroplets. The restitution coefficient can be piecewise fitted as the power functions of the impact Weber number of nanodroplets, regardless of the droplet diameters and ridge configurations. This work elucidates the characteristics and mechanism of nanodroplets impacting on the nanoridged surfaces, which is conducive to the design of nanostructured surfaces for related applications.