Heat vortexes of ballistic, diffusive and hydrodynamic phonon transport in two-dimensional materials

TL;DR

This paper investigates heat vortex phenomena in two-dimensional materials like graphene, revealing their occurrence in ballistic and hydrodynamic regimes but not in diffusive regimes, based on phonon transport modeling.

Contribution

It provides a detailed analysis of heat vortexes in 2D materials considering different phonon scattering regimes using the Boltzmann transport equation.

Findings

Heat vortexes appear in ballistic and hydrodynamic regimes.

Heat vortexes disappear in the diffusive regime.

Presence of R scattering suppresses vortex formation.

Abstract

In this work, the heat vortexes in two-dimensional porous or ribbon structures are investigated based on the phonon Boltzmann transport equation (BTE) under the Callaway model. First, the separate thermal effects of normal (N) scattering and resistive (R) scattering are investigated with frequency-independent assumptions. And then the heat vortexes in graphene are studied as a specific example. It is found that the heat vortexes can appear in both ballistic (rare R/N scattering) and hydrodynamic (N scattering dominates) regimes but disappear in the diffusive (R scattering dominates) regime. As long as there is not sufficient R scattering, the heat vortexes can appear in present simulations.