A particle-based multiscale model for submicron fluid flows

Abstract

A particle-based multiscale model for submicron fluid flow is proposed in this work. The model is based on a combination of a dissipative-particle dynamics (DPD) model for the mesoscales and molecular dynamics (MD) for the atomistic scales. The coarse-graining procedure involved in deriving DPD from MD is systematically exploited in this work to transition from the atomistic region to the mesoscale region. Coarse-graining results in filtering of smaller scales. The continuity of thermodynamic and transport properties across the interface is facilitated by appropriate selection of model parameters and the modeling of particle flux across layers. The model is applied to solve Poiseuille and Couette flows and flow over a rough wall. Results are compared with full-scale MD simulations. The model is also employed to solve microscale flows with slip at the wall. In the case of the Poiseuille and Couette flows, the results are found to differ from the analytical solutions by less than 10%. The differences with full-scale MD simulation results are within 5% for flow over an obstacle. The reduction in computational cost with increasing coarse graining is also evaluated.