An array of appealing and challenging technological applications involve spraying of liquids on liquid substrates, a process occurring at the nanometer level. However, due to the small scales involved there is currently a lack of solid understanding of the prevailing phenomena that, ultimately, control the process. Therefore, thorough study and analysis of the fundamental physical mechanisms and behaviour of these systems becomes a critical issue.

In this paper, several aspects of the dynamic behaviour of spraying of liquid nanodroplets on liquid substrates are investigated using molecular dynamics (MD) computer simulations. The liquid droplets consist of 10,000 to 100,000 atoms with Lennard-Jones interactions. We simulate the accelerated movement of such droplets and their splashing on a thick liquid layer. We study and analyse the mechanisms with which a droplet hits the substrate and becomes absorbed as well as the subsequent smoothing process. Aside from the physical mechanisms revealed associated with the small scale of these systems, the results are expected to provide valuable insights for improving nano-scale based processes like drug inhaling delivery systems.