Scale Effects in Nanoscale Heat Transfer for Fourier's Law in a Dissimilar Molecular Interface

The dependence of the heat transfer of a nanoscopic liquid channel residing at the solid-liquid interface is traditionally ascribed to the temperature jump, interfacial thermal resistance, wettability, and heat flux. Other contributions stemming from the channel width dependence such as the boundary position are typically ignored. Here, we conducted nonequilibrium molecular dynamics simulations to better understand the relation between channel width and boundary positions located at the solid-liquid interface. The system under investigation is a simple liquid confined between the solid from nanochannels of different sizes (3.27-7.35 nm). In this investigation, the existence of the correlation between the boundary position and the channel width is observed, which follows an exponential function. The thermal conductivity of the boundary positions is compared with the experimental value and Green-Kubo prediction to verify the actual boundary position. Atomistic simulation reveals that the solid-liquid boundary position, which matches the experimental value of thermal conductivity, varies with the channel width because of the intermolecular force and the phonon mismatch of the solid and the liquid.