Simulation of Dripping Using Dissipative Particle Dynamics

Dissipative Particle Dynamics (DPD) is a mesoscopic simulation approach used in wide range of applications and length scales. In this paper, a DPD simulation is carried out to study dripping flow from a nozzle. The results of this study are used to answer this question that whether DPD is capable of simulating the free surface fluid on all different scales. A novel wall boundary condition is developed for the nozzle surface that controls its penetrability, near wall fluid density oscillations and the fluid slip close to the wall. We also utilize a new method to capture the real-time instantaneous geometry of the drop. The obtained results are in good agreement with the macroscopic experiment except near the breakup time, when the fluid thread that connects the primitive drop to the nozzle, becomes tenuous. At this point, the DPD simulation can be justified by thermal length of DPD fluid and the finest accuracy of the simulation that is the radius of a particle. We finally conclude that in spite of the fact that DPD can be used potentially for simulating flow on different scales, it is restricted to the nanoscale problems, due to the surface thermal fluctuations.