Lattice-Boltzmann simulation of dense nanoflows: A comparison with Molecular Dynamics and Navier-Stokes solutions

In a recent work, a dense fluid flow across a nanoscopic thin plate was simulated by means of Molecular Dynamics (MD) and Lattice Boltzmann (LB) methods. It was found that in order to recover quantitative agreement with MD results, the LB simulation must be pushed down to sub-nanoscopic scales, i.e. fractions of the range of molecular interactions. In this work, we point out that in this sub-nanoscopic regime, the LB method works outside the hydrodynamic limit at the level of a single cell spacing. A quantitative comparison with the Navier-Stokes (NS) solution shows however that LB and NS results are quite similar, thereby indicating that, apart for a small region past the plate, this nanoflow is still well described by hydrodynamic equations.