Performance and influence of numerical sub-models on the CFD simulation of free and forced convection in double-glazed ventilated façades

Double-glazed façades (DGF) are an attractive option in contemporary architecture and are increasingly used in commercial buildings. They offer some advantages compared with single façade systems but require careful design. The solar-collector-like construction leads to high temperatures in the façade cavities and the possibility of the building overheating. This is undesirable effect, especially in Mediterranean climates. A possible solution for reducing thermal overheating is to use the air channel between the two layers of glass to evacuate the solar radiation absorbed by the façade. A suitable simulation procedure for modeling these façades would be very useful for designing buildings of this type.The use of computational fluid dynamics (CFD) has been broadly extended in order to gain insight into this problem, but selecting suitable sub-models for the convection, radiation and turbulence effects remains a big challenge. In this work, several modeling tests were carried out on a well-documented experimental test case taken from the open literature in order to obtain a suitable model of the aforementioned thermo-fluid-dynamics effects. Fluid and solid phase temperatures for a DGF configuration were obtained for three different radiation models and five different turbulence models, compared with experimental results available in the literature, and validated according to numerical verification and validation methodologies. From the results obtained it can be concluded that the P-1 radiation model seems to better predict the temperature of the solid phases present in the double façade. The RNG k − ɛ turbulence model seems to perform better than the other turbulence models tested for predicting heat transfer when there are zones of low velocities within the façade configuration. Only this combination of sub-models achieved numerical validation at pre-defined levels for the tested case.