ISSN Online: 2377-424X
International Heat Transfer Conference 12
A molecular dynamics simulation of a water droplet in contact with a platinum surface
Résumé
A water droplet in contact with a platinum surface was simulated by the molecular dynamics method. Water
molecules were modeled with the well-known SPC/E model and the platinum surface was represented by three
layers of harmonic molecules with the constant temperature heat bath model using the phantom molecules. Two
types of water-platinum pair potential functions based on extended Hückel calculations were employed, one was
developed by Spohr and Heinzinger in 1988 and the other was proposed by Zhu and Philpott in 1994. In the
spreading process of a liquid droplet on a platinum surface, the area of contact region between water and platinum
expanded just in proportion to the one-third power of time. This spreading rate was clearly in contrast to the case of
Lennard-Jones droplet. Even though the water droplet finally spread to a monolayer film on a fcc (111) surface
with the S-H potential, a stable droplet structure on a monolayer film was realized with the Z-P potential. The
mechanism of the 'drop on film' structure was explained by the very concentrated monolayer film of water.
Comparing three different platinum surface structures, (111), (100) and (110), the contact angle varied drastically
and it was largest on the fcc (100) surface.