Deviation from the Fourier law in room-temperature heat pulse experiments

TL;DR

This paper demonstrates that room-temperature heat pulse experiments deviate from Fourier's law and are better modeled by the Guyer--Krumhansl equation, revealing conduction channels with varying conductivities as the cause.

Contribution

It shows that the Guyer--Krumhansl equation accurately describes heat pulse behavior at room temperature, highlighting the limitations of Fourier's law in such conditions.

Findings

Fourier's law fails to describe heat pulse data at room temperature.

Guyer--Krumhansl equation captures over-diffusion regime in experiments.

Conduction channels with different conductivities cause the deviation.

Abstract

We report heat pulse experiments at room temperature that cannot be described by Fourier's law. The experimental data is modelled properly by the Guyer--Krumhansl equation, in its over-diffusion regime. The phenomenon is due to conduction channels with differing conductivities, and parallel to the direction of the heat flux.