title: Time-dependent and outflow boundary conditions for Dissipative Particle Dynamics.
abstract: We propose a simple method to impose both no-slip boundary conditions at fluid-wall interfaces and at outflow boundaries in fully developed regions for Dissipative Particle Dynamics (DPD) fluid systems. The procedure to enforce the no-slip condition is based on a velocity-dependent shear force, which is a generalized force to represent the presence of the solid-wall particles and to maintain locally thermodynamic consistency. We show that this method can be implemented in both steady and time-dependent fluid systems and compare the DPD results with the continuum limit (Navier-Stokes) results. We also develop a force-adaptive method to impose the outflow boundary conditions for fully developed flow with unspecified outflow velocity profile or pressure value. We study flows over the backward-facing step and in idealized arterial bifurcations using a combination of the two new boundary methods with different flow rates. Finally, we explore the applicability of the outflow method in time-dependent flow systems. The outflow boundary method works well for systems with Womersley number of O(1), i.e., when the pressure and flowrate at the outflow are approximately in-phase.
authors.affiliation: Division of Applied Mathematics, Brown University, Providence, RI 02912 USA.
authors.forename: Huan
authors.initials: H
authors.lastname: Lei
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Fedosov
authors.forename: George Em
authors.initials: GE
authors.lastname: Karniadakis