Effects of density on flow in a nano channel using a molecular-continuum hybrid method

Abstract

A molecular-continuum hybrid method was developed to simulate micro- and nano-scale fluid flows that cannot be predicted using continuum fluidics. Molecular dynamics simulation was used near stationary solid surfaces, and Navier-Stokes equations were used in other regions. We carried out Couette flow simulation using this hybrid method and validated the results by comparing them with the analytical solution. We also studied the dependence of the velocity slip and slip length on the surface energy, liquid density, and roughness for a liquid channel flow with and without nano-structures on the solid surface. The behavior of the liquid near the solid wall changed with the surface energy as well as the liquid density. The variation of the velocity slip and slip length according to the surface energy also depended on the liquid density as well as the surface roughness. We compared the required computational time obtained from the molecular-continuum hybrid method with that obtained from full molecular dynamics simulation under the same computational condition, giving much shorter computational time for the case using the molecular-continuum hybrid method than that for full molecular dynamics simulation.