Heat transfer between elastic solids with randomly rough surfaces

TL;DR

This paper investigates heat transfer mechanisms between elastic solids with rough surfaces, considering both contact and non-contact regions, including radiative transfer via evanescent waves, using advanced contact mechanics theory.

Contribution

It introduces a comprehensive model that accounts for hierarchical surface roughness and includes radiative heat transfer in non-contact regions, extending previous contact mechanics approaches.

Findings

Real contact areas are nanometer-sized regions affecting heat transfer.

Evanescent electromagnetic waves significantly contribute to heat transfer in smooth surfaces.

Hierarchical roughness impacts the overall heat transfer between solids.

Abstract

We study the heat transfer between elastic solids with randomly rough surfaces. We include both the heat transfer from the area of real contact, and the heat transfer between the surfaces in the noncontact regions. We apply a recently developed contact mechanics theory, which accounts for the hierarchical nature of the contact between solids with roughness on many different length scales. For elastic contact, at the highest (atomic) resolution the area of real contact typically consists of atomic (nanometer) sized regions, and we discuss the implications of this for the heat transfer. For solids with very smooth surfaces, as is typical in many modern engineering applications, the interfacial separation in the non-contact regions will be very small, and for this case we show the importance of the radiative heat transfer associated with the evanescent electromagnetic waves which exist outside of all bodies.