Atomization and Sprays

MOLECULAR DYNAMICS SIMULATIONS OF NANODROPLET WETTING ON A SOLID SURFACE

RESUMO

Surface wettability is of fundamental importance to myriad of applications including many spray systems. It represents a multiscale phenomenon with scales ranging from continuum to molecular. In this paper, we report molecular dynamics (MD) simulations to investigate wetting characteristics of a nanodroplet on a solid surface. The shape of an initially spherical liquid droplet in contact with two solid surfaces has been studied by applying continuous pressure from two atomistic moving surfaces. An efficient algorithm has been developed to track the liquid-phase interface and the dynamic contact angle θ, and characterize the wetting properties under the forced spreading of a droplet on a surface. Using a relatively small number of atoms (on the order of 10 ), the algorithm has been demonstrated to reproduce the entire wetting regime 0° < θ < 180° by varying the solid-liquid interaction energy. Extensive simulations have been performed to investigate the effects of changes in surface and liquid droplet characteristics on the wetting phenomena and contact angle. Results indicate a highly complex relationship between the contact angle and many surface and liquid characterizing parameters. The present study clearly demonstrates that MD simulations can be effectively used for a fundamental investigation of the wetting phenomena under forced spreading, and for characterizing the effects of surface tension and other macroscopic properties on wettability by suitably changing the liquid and surfaces molecular parameters.