Gilberto Domingues

Near-field heat transfer mediated by surface wave hybridization between two films

Using the general formalism of the fluctuational electrodynamics we extend the classical theory of near-field heat transfer between massive materials to any couple of films. An analytic expression for the net flux exchanged between two films in nonequilibrium thermal situation is derived. We show that the finite size effects and specifically hybridization of nondegenerated surface modes throughout the intrafilm cavity radically change the features of noncontact heat exchanges. This result should have important implications in the study of near-field heat transport between nanostructured materials.

Tailoring the local density of states of nonradiative field at the surface of nanolayered materials

The ability to artificially grow in a controllable manner at nanoscale, from modern deposition techniques, complex structural configurations made with metallic, polar, and semiconductor materials raises today the issue of the “best” achievable inner structure to tailor the near-field properties of a nanostructured medium. In the present work we make a step toward the rational design of these materials by reporting numerical experimentations demonstrating the possibility of identifying structural configurations of layered metallodielectric media specifically designed to control the electromagnetic density of states in the close vicinity of their surface. These results could find broad applications in near-field technologies.

Towards the development of simple methods for determining normal absorptances of open-cell foams based on opaque materials

The knowledge of the normal spectral absorptances of open-cell foams used as volumetric solar receivers is required to finely compute their thermal efficiencies. For this purpose, absorptances of a set of virtual open-cell foams of varying porosities, beforehand generated by using a numerical generator, are computed thanks to a ray tracing code. This work details the contribution of the intrinsic optical properties of the solid phase to the normal spectral absorptance of open-cell foams, through the statistical analysis of both the path and the events undergone by a ray, which is permitted by the ray tracing code. This study allows us to propose a robust and linear relationship that links the normal spectral absorptance to the porosity and the intrinsic optical properties of the solid phase, which is considered as optically thick.