Integrated simulation simulation of continuous-scale and discrete-scale radiative transfer in an open-cell foam made of semitransparent absorbing-scattering ceramics

摘要

A novel scale-coupled approach was proposed to model the radiative transfer inside open-cell foams made of semitransparent absorbing-scattering media such as oxide ceramics. This new approach was established by integrating the equivalent continuous zone with the exact distribution of solid and void zones into a single computational domain. As a key treatment, a scale-coupled zone with variable local optical and radiative properties was proposed to allow gradual transition between different subzones. After a validation by experiments on a normal transmittance measurement, the scale-coupled approach was applied in predicting the radiative behaviors and local absorbed radiative fluxes of a real alumina ceramic foam. The results were confronted with the classical continuous-scale approach which assimilates the foam material to an equivalent continuous medium with homogeneous radiative properties and discrete-scale approach which considers the exact distribution of foam geometry in the medium. This new approach was found reliable in calculating the radiative behaviors of open-cell foams made of relatively opaque to transparent or relatively absorbing to scattering media. It can offer information on the fluctuant local radiative quantities and at the same time equivalent continuous quantities through a single simulation. Besides, this new approach leads to a reduction in computational time by approximately one order of magnitude compared to the discrete-scale approach which relies on full-size foam geometry. The scale-coupled approach is promising to simulate engineering problems where geometry-dependent radiative quantities are required. (C) 2018 Elsevier Ltd. All rights reserved.