Development of a boundary-coupled CFD model for collimated-diffusive radiation

Abstract

This work presents the development and implementation of a collimated-diffuse radiation model based on the Surface-to-Surface (S2S) approach within the OpenFOAM framework. The model aims to provide a computationally efficient tool for simulating solar radiation in engineering applications, such as solar collectors and buildings. Unlike existing approaches in the literature, the proposed model offers a more accurate representation of thermal radiation by implementing boundary conditions that account for both diffuse and collimated radiation. The model validation was conducted through a series of numerical cases where the medium is always transparent or non-participating. These cases include square cavities where only the radiation equations are solved, as well as others that consider coupled fluid-radiation interactions. The analyzed cases encompass purely collimated, diffuse, and combined radiation conditions. The obtained results demonstrate the model’s accuracy in solving coupled radiation-convection problems and highlight significant differences when comparing constant heat flux boundary conditions with those obtained using the collimated-diffuse radiation model.