A particle based analysis is carried out to simulate formation of a viscous Newtonian liquid drop from a mesoscale nozzle into an inert medium by imposing low flow rate says dripping. In the case of mesoscale free surface flow, thermal fluctuations become important as they can no longer be justifiable with the continuum perturbation theory. On the other hand, the resolution of this scale is beyond the applicability of Molecular Dynamics. Therefore this category of physics problems is remarkably challenging. According to mentioned conditions, Dissipative Particle Dynamics (DPD) is an eligible method. In seeking validation of method, dripping simulation is compared with macroscopic experiment. This comparison is governed by matching only Ohnesorge number and bond number and leaving dimensionless thermal length unmatched. Our results are in good agreement with the macroscopic experiment except near the break-up time, when the fluid thread that connects the primitive drop to the nozzle, becomes tenuous. At this point, the DPD simulation comes into question by two issues: thermal length of DPD fluid and the finest achievable resolution that is radius of a particle. The former was much longer than corresponding value in physics of mentioned experiment. Larger thermal length leads to break-up which happens before expected time. However this simulation could be observed in different way; in fact it corresponds to physics of dripping from a nano nozzle that thermal length of both are matched. Accordingly in this view fast drop break-up would be intelligible. A nano-jet in a centrifugal field is simulated by DPD. The simulation is run in a rotating reference frame that results in the addition of fictitious forces to DPD inter-particle forces. In seeking validation of trajectory of jet, DPD simulation is comprised with continuum theory.It is shown that the occurrence of mode 1 and mode 2, which are observed in macroscopic, is unlikely in nano-scale. Mode 3 and mode 4 of breakup is simulated by DPD. Fast breakup of spiralling jet in mode 3 is justified with surface thermal fluctuations. The Simulation of mode 4 of breakup is similar to that of macroscopic. The breakup length of jets are measured as a function of Roy number in nano-scale and compared with macroscopic one. Although they have the same procedure, breakup length of nano-scale jets are apparently shorter than macroscopic jets. This difference is also the consequence of thermal fluctuation in nano-scale. Key Words: Dissipative Particle Dynamics, Nano and micro flows, Two-phase flows, Nano-Jet, Drop, Spiralling Jet, Breakup.
