Controlling particle penetration and depletion at the wall using Dissipative Particle Dynamics

First presented in 1993, Dissipative Particle Dynamics(DPD) has gained increasingly popularity in the scientific community due to its extensive potential to be employed in a broad range of mesoscale systems, such as polymers, colloids, surfactants and many other multi-phase systems. Although much research has been done in DPD systems, a challenge still persists when physical boundaries, such as the presence of walls, are present. One of the main issues is to achieve the non-slip condition while avoiding density distortions at the wall. In this work, particle penetration and depletion, calculated respectively as the fraction of particles in the first and second layer of the simulation box, are tracked and controlled in a wall-bounded DPD model by tuning two parameters: the wall–particle interactions and wall density. A similar response in terms of wall penetration and depletion was observed when different ratios wall/fluid for both interactions and density were employed, although increasing the wall density was found to have a slightly stronger influence in keeping the particles away from the wall region. By quantifying the fraction of particles in each layer the present authors were able to track their distribution across the channel as well as determine the combinations wall-density/interactions capable of avoiding wall penetration while depletion is controlled.