improvement of dissipative particle dynamics method by taking into account the particle size

In this paper, ow past a single dissipative particle dynamics (dpd) particle with low reynolds number is investigated and whether a single dpd particle immersed in a uid has an intrinsic size is surveyed. then, a minimum length scale is determined such that the hydrodynamic behavior based on standard dpd formulation is modeled correctly. almost all of the previous studies assume the dpd particles as point centers of repulsion with no intrinsic size. hence, to prescribe the size of a simulating sphere, a structure for frozen dpd particles is proposed. in this paper, two effective radii, namely stokes-einstein radius and a radius based on the stokes law, for dpd particles are introduced. for small reynolds numbers, it was proved that the two radii approached each other. finally, in spite of the typical simulations which assume dpd particles as point centers of repulsion, it was concluded that each of the individual dpd particles interacted with other particles as a sphere with non-zero radius. this resulted in reduction in the required number of particles and led to more economical simulations. contemplating the radius of the particles was necessary for the new low-dimensional model, which was derived from the dpd method.