Effect of curved surfaces on the impacting nano-droplets and their shape control: A molecular dynamics simulation study

Considerable non-flat solid substrates are widely-existed where liquid drops inevitably impact on their surfaces, precise control of shape evolution of these impacting drops on such surfaces is desired in nature and some advanced technologies. Herein, a common but less-concerned substrate with curvature is used to investigate the impact dynamic of liquid metals by performing molecular dynamics (MD) simulations, which exhibits anisotropic impact behavior with distinct spreading and retraction in the two perpendicular directions and results in an elongated strip-like shape during shape evolution. The effects of curvature diameter, liquid properties (drop size and surface tension), and impact velocity are deeply demonstrated by quantitatively comparing the value of length ratio that is defined to describe the drop asymmetrical impact behaviors. This work helps advance our understanding of how the liquid metal evolves after impact on the curved surface and provides some feasible strategies to control its deposition and shape for some potential applications, such as 3D printing techniques, special coating, as well as drop-casting process.