Hydrodynamics in a nanoscale liquid: comparisons with molecular dynamics in non-stationary processes

Abstract

Molecular dynamics (MD) and Navier–Stokes hydrodynamics have been performed to model the thermal relaxation processes arising from an initially established non-equilibrium stationary state. A nanoscale two-layer Lennard–Jones (LJ) liquid system was constructed in which the two parts were initially at a different temperature. The hydrodynamics model used parameterized MD-derived transport coefficients and the LJ equation of state as input functions. The temporal and spatial temperature and density profiles produced by the two methods show good agreement, indicating that a hydrodynamics description is reliable even for non-stationary phenomena down to the scale of a few nanometers. The Navier–Stokes solver can be used on length scales up from the nanoscale. One can envisage this approach being useful in the area of microfluidics device design, for instance.

Keywords:

• Nanoscale liquids
• Non-stationary processes
• Hydrodynamics
• Molecular dynamics

Acknowledgements

I would like to thank Professor David M. Heyes for valuable discussions. This work was supported by a Grant-in-Aid for Scientific Research (grant No. 17740260) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.