Scale effect on flow and thermal boundaries in micro-/nano-channel flow using molecular dynamics-continuum hybrid simulation method

Abstract

The molecular dynamics (MD)-continuum hybrid simulation method has been developed in two aspects in the present work: (1) The energy equation has been combined into the coupling method in order to obtain the hybrid temperature profile and (2) the coupling method has been improved by the local linearization to obtain a smoother parametric profile. The developed method is primarily validated by analytical solutions and full MD results. Then, it is employed to study the scale effect on the flow and thermal boundaries in micro-/nano-channel flow. The hybrid velocity and temperature profiles are obtained with the channel height (H) ranging from 60σ to 2014σ and the solid-liquid coupling (β) ranging from 0.1 to 50. Scale effect has shown strong influence on the boundaries. Obvious slip characteristics can be found in the profiles, i.e. velocity slip and temperature jump, when H is small and is large. However, the results also show that the profiles can be well predicted to converge to the macroscale non-slip/non-jump analytical solutions when H is β large enough, where the effect of β can be omitted and the slip characteristics disappear. Correlations of relative slip length, relative temperature jump and pressure gradient with H are fitted from the simulation results. © 2009 John Wiley & Sons, Ltd.