Next: Determination of kinematic Up: Basic DPD Equations Previous: Integration of the equations
Groot and Warren (1997) found that choosing a number density of three DPD particles per unit volume (where as defined earlier, the unit of length is rc) was a practical choice for modeling the fluid phase. The equilibrium properties of the fluid are reasonably well defined here and going to higher densities quickly becomes expensive computationally. The rigid bodies were introduced by randomly placing their center of mass positions in the simulation cell. This sphere packing process, of course, leads to overlaps of the rigid bodies. A repulsive force was introduced that pushed the overlapping rigid bodies apart. Once the spheres were separated, the final configuration was used as an input for beginning the simulations.
For most of the results presented, a Lees–Edwards boundary condition [Allen and Tildesley (1987)] was used. It effectively produces a shearing effect akin to an applied constant strain rate at the boundaries. Applications of other boundary conditions will be described later in the paper.