Nonlocal hydrodynamic phonon transport in two-dimensional materials

TL;DR

This paper develops a nonlocal hydrodynamic model for phonon heat transport in 2D materials, revealing phenomena like heat vortices and negative conductance, and demonstrating universal hydrodynamic behavior across quasi-particles.

Contribution

It derives a 2D Guyer-Krumhansl-like equation for phonon transport that includes flexural phonons and predicts novel hydrodynamic effects in 2D materials.

Findings

Prediction of heat vortices in 2D materials

Identification of negative nonlocal thermal conductance

Universal behavior of hydrodynamic phonon transport

Abstract

We study hydrodynamic phonon heat transport in two-dimensional (2D) materials. Starting from the Peierls-Boltzmann equation within the Callaway model, we derive a 2D Guyer-Krumhansl-like equation describing non-local hydrodynamic phonon transport, taking into account the quadratic dispersion of flexural phonons. In additional to Poiseuille flow, second sound propagation, the equation predicts heat current vortices and negative nonlocal thermal conductance in 2D materials, common in classical fluid but scarcely considered in phonon transport. Our results also illustrate the universal transport behavior of hydrodynamics, independent on the type of quasi-particles and their microscopic interactions.