Mesoscopic kinetic model of wettability: From molecular dynamics to thermodynamics

We present a mesoscopic kinetic model for the wettability of the liquid–vapor fluids on a solid substrate by handling microscopic molecular interactions. The fluid internal potential energy is refined to incorporate the solid–fluid molecular interaction, and then the usual macroscopic thermodynamic quantities are consistently found. An effective solid density containing microscopic details is identified to determine the macroscopic state of complete drying, partial wetting, or complete wetting. Furthermore, a concise graphical rule is derived for the contact angle in the partial wetting state. This mesoscopic kinetic model of wettability, validated by consistent lattice Boltzmann modeling, successfully bridges microscopic molecular interactions and macroscopic thermodynamic properties.