Nonlocal Effects and Slip Heat Flow in Nanolayers.

Guyer-Krumhansl (G-K) equation is a promising macroscopic model to explore heat transport in nanoscale. In the present work, a new nonlocal characteristic length is proposed by considering the effects of heat carriers-boundaries interactions to modify the nonlocal term in G-K equation, and a slip heat flux boundary condition is developed based on the local mean free path of heat carriers. Then an analytical solution for heat flux across 2-D nanolayers and an in-plane thermal conductivity model are obtained based on the modified G-K equation and the slip heat flux boundary. The predictions of the present work are in good agreement with our numerical results of direct simulation Monte Carlo (DSMC) for argon gas nanolayer and the available experimental data for silicon thin layers. The results of this work may provide theoretical support for actual applications of G-K equation in predicting the thermal transport properties of nanolayers.