Mesoscale study of particle sedimentation with inertia effect using dissipative particle dynamics

Mesoscale dispersed two-phase flows often involve complicated dynamic behaviors. Grid-based methods within the framework of continuum mechanics are usually difficult to capture certain degree of molecular-level effect, while the molecular dynamics is only practical at extremely small temporal and spatial scales. In this paper, dissipative particle dynamics (DPD) is extended to the investigation of a fluid-solid sphere system with inertia effect within two parallel plates through the modification of DPD weighting function and hence the dynamic parameters. The sphere and walls are composed of frozen DPD particles that are first treated to reach equilibrium state in the simulation. The force on the solid sphere is obtained from all the particles included in the sphere. The drag coefficient of the frozen sphere is evaluated and compared with the classical correlations. The initial value problem for the sedimentation of the sphere is then solved at certain Reynolds numbers, which is consistent with our direct numerical simulation results.