Combination of Boundary Singularity and Direct Simulation Monte Carlo Methods for Nano-scale Flows

A novel hybrid method combining the continuum approach based boundary singularity method (BSM) and the molecular approach based direct simulation Monte Carlo (DSMC) is developed and then used to study viscous fibrous filtration flows in the transition flow regime, . This approach may be useful for modeling of detection and signaling in micro-fluidic sensors. The DSMC is applied to an annular region enclosing the solid fiber and the BSM is employed to the entire flow domain. The parameters used in the DSMC and the coupling procedure, such as the number of simulated DSMC particles, the cell size and the size of the coupling zone are determined. It is observed that in the partial-slip flow regime the results obtained by the hybrid BSM-DSMC method match the ones from the BSM combined with the heuristic partial-slip boundary conditions. For higher Knudsen numbers, the difference in pressure drop and velocity is significant. The developed hybrid method is then parallelized by using MPI and extended for multi-fiber filtration flows. The multi-fiber filter flows considered are in the partial-slip and transition regimes. The proposed combined continuum and molecular methodology can incorporate surface chemical reactions and the electromagnetic forces in the DSMC procedure for Knudsen layer.