A new model for dissipative particle dynamics boundary condition of walls with different wettabilities

Abstract

The implementation of solid-fluid boundary condition has been a major challenge for dissipative particle dynamics (DPD) method. Current implementations of boundary conditions usually try to approach a uniform density distribution and a velocity profile close to analytical solution. The density oscillations and slip velocity are intentionally eliminated, and different wall properties disappear in the same analytical solution. This paper develops a new wall model that combines image and frozen particles and a new strategy to emphasize different wall properties especially wettabilities. The strategy first studies the realistic wall-fluid system by molecular dynamics (MD) simulation depending on physical parameters. Then, a DPD simulation is used to match the density and velocity profiles with the new wall model. The obtained DPD parameters can simulate the systems with the same wall and fluid materials. With this method, a simulation of the Poiseuille flow of liquid argon with copper walls is presented. Other walls with super-hydrophilic, hydrophilic, and hydrophobic wettabilities are also simulated. The limitations of the analytical solution and the effect of the wall-fluid interaction are discussed. The results show that the method suggested in this paper can simulate the mesoscale behavior of the microchannel flow related to realistic systems.