  Dissipative particle dynamics (DPD) is an effective mesoscopic particle model
with a lower computational cost than molecular dynamics because of the soft
potentials that it employs. However, the soft potential is not strong enough to
prevent the DPD particles that are used to represent the fluid from penetrating
solid boundaries represented by stationary DPD particles. A phase field
variable, , is used to indicate the phase at point and time t, with a smooth
transition from -1 (phase 1) to +1 (phase 2) across the interface. We describe
an efficient implementation of no-slip boundary conditions in DPD models that
combines solid-liquid particle-particle interactions with reflection at a sharp
boundary located with subgrid scale accuracy using the phase field. This
approach can be used for arbitrarily complex flow geometries and other similar
particle models (such as smoothed particle hydrodynamics), and the validity of
the model is demonstrated by DPD simulations of flow in confined systems with
various geometries.
