Heat transfer characteristics in nanochannels with rough walls based on capillary flow: A molecular dynamics study

Abstract

Passive micro/nanoscale cooling based on capillary flow has become a promising and widely used thermal management technology for electronic devices. In this study, nanochannels with different surface roughness are established based on the chord function, and the capillary flow and heat transfer in different nanochannels are investigated by molecular dynamics simulation. Compared with smooth walls, rough walls retard capillary flow, and the heat transfer process also affects capillary flow to some extent. The region of low potential energy is much larger near rougher walls in nanochannels. When fluid flows through a depression on a wall, the velocity decreases, resulting in an uneven flow velocity. An analysis of the temperature field, Nusselt number and heat transfer amount shows that although rougher structure causes more atoms to gather, thus improving the heat transfer rate, it reduces the total heat transfer amount due to reduced capillary flux. The microscopic mechanism of the impact of surface roughness on capillary flow and heat transfer is revealed at the atomic scale by potential energy analysis. Furthermore, increasing solid-liquid interaction hinders capillary flow, but it increases the heat transfer rate at the solid-liquid interface.