Large-eddy simulation-based wind and thermal comfort assessment in urban environments

This study analyzed the thermal wind environment at the pedestrian level around urban geometry featuring high-rise buildings using building-resolved large-eddy simulation (LES) while incorporating seasonal atmospheric data. The synthetic inflow generation method and immersed boundary method with wall-function were applied for urban thermal flow LES. The solver was validated using wind tunnel experiments based on the metrics, namely RMSE, FAC2, and hit rates q. The study conducted LESs of thermal wind environments around the Yonsei University campus, featuring two high-rise buildings. The LES results showed that downdraft wind and large-circulation (known to be idealized high-rise building-induced) also occurred around realistic high-rise buildings in urban areas. These induced flows enhanced building wind via the Venturi effect and lowered temperatures at the pedestrian-level by drawing cool air downwards. Additionally, by comparing conditionally averaged quantities on the campus with and without high-rise buildings, we quantified the extent of the building's impact on the urban thermal environment at the pedestrian-level.