Heat transfer in granular media with weakly interacting particles

TL;DR

This paper investigates heat transfer mechanisms in weakly interacting, fractal-surfaced mineral particles in vacuum, highlighting electromagnetic waves as dominant contributors over phononic contact conduction, with applications to asteroid heat dynamics.

Contribution

It introduces a detailed analysis of electromagnetic heat transfer in weakly interacting particles with fractal surfaces, emphasizing the dominance of EM waves over phononic contact conduction.

Findings

EM waves dominate heat transfer for large particles

Evanescent EM waves dominate for small particles

Phononic contact contribution is negligible

Abstract

We study the heat transfer in weakly interacting particle systems in vacuum. The particles have surface roughness with self-affine fractal properties, as expected for mineral particles produced by fracture, e.g., by crunching brittle materials in a mortar. We show that the propagating electromagnetic (EM) waves and the evanescent EM-waves, which occur outside of all solids, give the dominant heat transfer for large and small particles, respectively, while the phononic contribution from the area of real contact is negligible. As an application we discuss the heat transfer in rubble pile asteroids.