Viscous heat backflow and temperature resonances in extreme thermal conductors

TL;DR

This paper demonstrates that viscous heat equations can induce and control non-diffusive heat backflow and temperature resonances in extreme thermal conductors like graphite, enabling new thermal management strategies.

Contribution

It introduces the use of viscous heat equations to model and control heat backflow and resonances in high thermal conductivity materials, with quantitative first-principles validation.

Findings

Finite thermal viscosity creates steady-state heat vortices.

Thermal resonances can be amplified using device boundary strategies.

Transient temperature waves are governed by thermal viscosity.

Abstract

We demonstrate that non-diffusive, fluid-like heat transport, such as heat backflowing from cooler to warmer regions, can be induced, controlled, and amplified in extreme thermal conductors such as graphite and hexagonal boron nitride. We employ the viscous heat equations, i.e., the thermal counterpart of the Navier-Stokes equations in the laminar regime, to show with first-principles quantitative accuracy that a finite thermal viscosity yields steady-state heat vortices, and governs the magnitude of transient temperature waves. Finally, we devise strategies that exploit devices' boundaries and resonance to amplify and control heat hydrodynamics, paving the way for novel experiments and applications in next-generation electronic and phononic technologies.