Physically based wall boundary condition for dissipative particle dynamics

In this paper, we present a novel wall boundary condition model, which stands just on the physical facts, for the dissipative particle dynamics (DPD) method. After the validation of this model by means of the common benchmarks such as the Couette and the Poiseuille flows, we study the effects of this model on the diffusion coefficient in a wide variety of different coarse-graining levels. The obtained results show that the proposed model preserves the thermodynamics of the system, also eliminates the spurious effects of the wall, and consequently is able to preserve the accurate structural characteristics of the working DPD fluid in the wall’s vicinity. We also study the fluid flow through a channel with the polymer-coated walls. A comprehensive investigation into the wall–solvent–polymer interactions is presented for the solvents with different qualities. Since the working DPD fluid’s structure is heterogeneous, the working fluid’s structure, its density variations and the force field that is experienced by the working DPD fluid particles near the wall cannot be predicted before the simulation. Hence, all of these data have to be determined systematically during the simulation. We show that the force field experienced by the particles near the wall depends substantially upon the solvent quality. We also show that the force fields experienced by the particles from different types (solvent/polymer) in the wall’s vicinity are significantly different from each other except in the athermal solvent.