Molecular dynamics simulation of the contact angle of liquids on solid surfaces

摘要

Solid-liquid-vapor interaction phenomena have an important role in phase change heat transfer. In 2005, Sinha1 carried out simulation of contact angle using argon and a virtual solid wall. He modeled the solid-liquid interaction by a (9,3) potential and assumed that the solid surface is semi-infinite,nnwhere R0 is the lattice constant of a fcc(111) solid surface, z is the distance from wall, and ϵsf and σsf are Lennard-Jones parameters, respectively. In that study, it was found that the contact angle decreased with increasing temperature and no matter how the potential was changed, the trend was the same. Earlier in 2002, Maruyama et al.2 also simulated the contact angle of argon liquid on a virtual solid wall. They calculated various contact angles by changing the parameter ϵ in the potential between argon fluid and the virtual solid wall. They found that the contact angle decreased with an increase in interface potential and became 0° when the potential was set to a large enough value.nResults of limited molecular dynamics simulation studies have been reported in literature on the contact angle of water and a realistic solid wall. In 2003, Kimura and Maruyama3 first simulated a water droplet on a platinum surface. They used two different potentials between water and platinum. By using Spohr–Heinzinger4 potential, they found that the contact angle is always 0°, which suggests that this potential is not suitable to predict the contact angle. By using Zhu–Philpott5 potential, they successfully calculated the contact angle variation with the orientation of the crystal structure of a platinum wall at a temperature of 350 K.nIn this paper, the particle-particle particle-mesh (PPPM) method6 is applied to minimize the error in long range terms in both the Coulombic and Lennard-Jones potentials. Higher accuracy simulation is performed to obtain the contact angle variation with temperature and wall potential.