A molecular dynamics and lattice Boltzmann multiscale simulation for dense fluid flows

A molecular dynamics (MD)-lattice Boltzmann (LB) hybrid scheme has been adopted to simulate dense fluid flows. Based on the domain decomposition method and the Schwarz alternating scheme, the "Maxwell Demon" approach is used to impose boundary conditions from the continuum to the atomistic region, while the "reconstruction operator" is implemented to construct the single-particle distribution function of the LB method from the results of the MD simulation. Couette flows and the flow of a dense fluid argon around a carbon nanotube (CNT) are solved to validate the hybrid method. When the mesh of the LB domain is refined and the size of corresponding sampling cells of the MD domain is reduced, the fluctuations of the results between two successive iterations of the hybrid method become more severe, although the results get closer to the MD reference solutions. To decrease the fluctuation due to the mesh refinement, a new weighting function is proposed for the sampling of MD simulation results. Numerical practice demonstrates its feasibility.