Molecular dynamics study of anisotropic behaviours of water droplet on textured surfaces with various energies

The anisotropic wetting behaviours of water droplets on six surfaces with different solid-liquid interaction intensities are systemically investigated by molecular dynamics simulation. The six surfaces include Smooth, Square, Triangle, Sin, Sin-plus and Cylinder surfaces, and the interaction potentials between surface atoms and water molecules are adjusted to obtain various surface free energies. Moreover, the condensation process on those surfaces is investigated under a fixed solid-liquid interaction intensity. The wetting results indicate that surface energy plays an essential role in anisotropic wetting of the six surfaces. Moreover, under the fixed surface energy, the anisotropic wetting behaviours of water droplets are determined by the atom potential energy barrier and top area of solid substrate. The droplet on Square surface has most obvious anisotropic wetting behaviour because of its substantial atom potential energy barrier and large top area to support water droplet. In the condensation process, droplets nucleation, growth and coalescence processes are all visualised and quantitatively recorded, we find that texture creates lower atom potential energy on the surface and water molecules tend to nucleate on the area with low atom potential energy. Furthermore, the texture hinders the reunion of small clusters and consequently reduces the maximum cluster size.