Radiative heat transfer between metallic gratings using adaptive spatial resolution

TL;DR

This paper introduces an adaptive spatial resolution method to accurately compute radiative heat transfer between metallic gratings, revealing significant amplification effects and discrepancies with prior studies due to reflection operator issues.

Contribution

The paper presents a modified Fourier modal method with adaptive spatial resolution, enabling precise calculations of heat flux at small separations and across a wide range of grating heights.

Findings

Enhanced convergence rate for heat flux calculations.

Identification of spoof-plasmon modes causing energy amplification.

Quantitative disagreement with some previous results, linked to reflection operator issues.

Abstract

We calculate the radiative heat transfer between two identical metallic one-dimensional lamellar gratings. To this aim we present and exploit a modification to the widely-used Fourier modal method, known as adaptive spatial resolution, based on a stretch of the coordinate associated to the periodicity of the grating. We first show that this technique dramatically improves the rate of convergence when calculating the heat flux, allowing to explore smaller separations. We then present a study of heat flux as a function of the grating height, highlighting a remarkable amplification of the exchanged energy, ascribed to the appearance of spoof-plasmon modes, whose behavior is also spectrally investigated. Differently from previous works, our method allows us to explore a range of grating heights extending over several orders of magnitude. By comparing our results to recent studies we find a consistent quantitative disagreement with some previously obtained results going up to 50\%. In some cases, this disagreement is explained in terms of an incorrect connection between the reflection operators of the two gratings.