A hybrid MD-DSMC model for heat and mass transfer in micro- and nanochannels

In this research, local, convective cooling by integrated micro- and nanochannels is studied. In such devices the Knudsen number for gases and vapours (e.g. in phase transitional systems) is becoming so large, that the limit of a continuum approach is reached. Therefore particle-based methods have to be used such as Molecular Dynamics (MD) and Direct Simulation Monte Carlo (DSMC). In Molecular Dynamics, particle interactions are modelled in detail. Therefore it is an accurate but computationally expensive method. The Direct Simulation Monte Carlo method is based on the Enskog equation. The particle interactions are described in a stochastic way. Therefore a speed-up is achieved compared to MD, but the boundary effects are computed less accurate. A new hybrid MD-DSMC method is developed that combines the advantages of both methods: MD is used close to the channel walls, for the accuracy, and DSMC in the bulk, for the fast computations. The domains are coupled via interfaces. It is shown by several examples that, by this hybrid approach, a speed-up can be reached without loosing accuracy