CFD model validation and mesh resolution reduction strategies for complex louvred openings

Rising outdoor temperatures, the absence of effective overheating mitigation strategies and upcoming renovations contribute to a decrease in summer thermal comfort in homes. This heightens the need to provide occupants with adequate passive cooling strategies to avoid the use of energy-intensive active cooling systems. Louvred openings enable occupants to extend the well-established passive cooling strategy of natural ventilation to nighttime, periods of absence, and non-ideal weather conditions. As numerical investigations of indoor environmental quality with these systems are rare and validated CFD models do not 2exist, this study aims to validate a CFD model by conducting full-scale experiments, testing different turbulence models, and assessing the impact of radiation. Furthermore, various strategies to reduce the large number of mesh cells, caused by the complex geometry of the louvre, are studied. The final model shows good performance for low-velocity zones. In zones with higher velocity, namely the flow entry zone after the louvre, the model tends to overpredict velocities. No turbulence model is superior. Radiation modelling did not significantly improve the model performance but drastically increased the computational resources. The best strategy to reduce the mesh (by 63%) was the porous media model, which also improved the prediction of the high-velocity inflow zone. Additionally, allowing for higher surface curvature deviation did not significantly impact the flow but resulted in a 30% reduction of mesh cells.