Mesoscopic Simulations of Flow in Microchannel and Comparison With Continuum Model

Dissipative particle dynamics (DPD) is a mesoscopic particle-based simulation method, where each particle represents a group or packet of actual molecules of the flow field. Despite its usefulness, a fundamental problem of the DPD is that there is no straightforward procedure to relate the soft-particle model to a realistic continuum or molecular model. In the present work, we studied the dynamics of a simple fluid flow in a microchannel based on the coarse-graining of the molecules and expressed DPD units in terms of real units. To compare DPD methodology with continuum theory, a relation between the viscosity of the fluid and dissipative coefficient of DPD was established. DPD equations and parameters were expressed in non-dimensional forms and related to the known hydrodynamic parameters such as Reynolds number and Peclet number. Poiseuille flow of water in microchannel of height 35 μm was modeled for different parameters. Coarse-graining for water was ranged from 5×10⁹ to 5×10¹⁰ for each DPD particle. Re and Pe of the flow were varied from 0.7 to 60 and 5 to 140, respectively. Simulated results were compared to the continuum results with a good agreement.