Influence of roughness on near-field heat transfer between two plates

TL;DR

This paper investigates how surface roughness affects near-field heat transfer between two plates using second-order perturbation theory, providing insights into experimental conditions and the validity of the proximity approximation.

Contribution

It introduces a theoretical framework to quantify the impact of surface roughness on near-field heat transfer and assesses the validity of the proximity approximation in relevant regimes.

Findings

Surface roughness significantly influences near-field heat transfer.

The proximity approximation remains valid for distances much smaller than the roughness correlation length.

The results help interpret experimental measurements involving rough surfaces.

Abstract

The surface roughness correction to the near-field heat transfer between two rough bulk materials is discussed by using second-order perturbation theory. The results allow for estimating the impact of surface roughness to the heat transfer in recent experiments between two plates and between a microsphere and a plate (using the Derjaguin approximation). Furthermore, we show that the proximity approximation for describing rough surfaces is valid for distances much smaller than the correlation length of the surface roughness even if the heat transfer is dominated by the coupling of surface modes.