Atomistic evidence of hydrodynamic heat transfer in nanowires

With wave-packet propagation simulations and heat flux estimation via molecular dynamics, we show that the heat flux radial distribution in silicon nanowires can be described by a mesoscopic model, the hydrodynamic heat equation. We observe Poiseuille like heat flux profile, that cannot be described by a simple kinetic model such as the Fuchs-Sondheimer model, in both pristine and core/shell nanowires. The addition of a shell does not change the shape of the radial heat flux distribution, but just modifies the maximum of the heat flux in the center of the nanowire. These results show that there is a heat flux depletion length for pristine or core shell nanowires, 1-2 nm away from the boundary of the crystalline part. The parameters of the mesoscopic model are discussed in terms of microscopic properties, including the phonon mean free path as function of frequency and the partial vibrational density of states in the different regions of the nanowire. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

Using wave-packet propagation simulations and molecular dynamics, this study investigates the heat flux distribution in silicon nanowires. The study shows that the radial distribution of heat flux can be described by the hydrodynamic heat equation, revealing a Poiseuille-like profile. The addition of a shell does not alter the shape of the heat flux distribution, but modifies the maximum heat flux at the center of the nanowire. Furthermore, the study identifies a heat flux depletion length in pristine or core-shell nanowires. The parameters of the mesoscopic model are discussed in terms of microscopic properties.