Effects of ballistic transport on the thermal resistance and temperature profile in nanowires

TL;DR

This paper investigates how ballistic phonon transport influences temperature distribution and thermal resistance in nanowires, combining simulations and a radiator model to explain the effects.

Contribution

It introduces a comparison between molecular dynamics, phonon Monte Carlo simulations, and a radiator model to explain ballistic transport effects in nanowires.

Findings

Ballistic transport reduces temperature gradients in nanowires.

The radiator model accurately predicts temperature profiles for wires longer than phonon mean free path.

Steep temperature gradients at wire ends are due to discrete jumps in the model.

Abstract

Effects of ballistic transport on the temperature profiles and thermal resistance in nanowires are studied. Computer simulations of nanowires between a heat source and a heat sink have shown that in the middle of such wires the temperature gradient is reduced compared to Fourier's law with steep gradients close to the heat source and sink. In this work, results from molecular dynamics and phonon Monte Carlo simulations of the heat transport in nanowires are compared to a radiator model which predicts a reduced gradient with discrete jumps at the wire ends. The comparison shows that for wires longer than the typical mean free path of phonons the radiator model is able to account for ballistic transport effects. The steep gradients at the wire ends are then continuous manifestations of the discrete jumps in the model.