Large-eddy simulations of typhoon-landfall gust generation in areas surrounding super high-rise buildings

This study examines how a high-rise building complex (HB) in the Haeundae District of Busan, South Korea influences nearby airflow structures and gust generation using the Parallelized Large-Eddy Simulation Model (PALM) Version 6.0. The simulations were validated by comparing modeled wind speeds with observations collected during the landfall of Typhoon Hinnamnor that impacted the Busan area. To examine the influence of building height, we conducted a set of scenario experiments in which HB height was modified from 0% to 75% of the actual height in 25% increments. The results indicate that increasing HB height strengthens downdrafts and enhances flow separation, which markedly elevates pedestrian-level mean wind speeds and turbulent wind speeds. Meanwhile, the gust factor decreases as HB height increases, implying that gust factor alone is insufficient for representing gust intensity under strong-wind conditions. To compensate for this limitation, we conducted an additional analysis centered on turbulent gusts, showing that gust intensity rises in densely built low-rise areas adjacent to HB as HB height increases. Gust probability analysis further suggests that extreme gust events were very rare during typhoon landfall; however, with greater HB height, the occurrence of moderate and strong gusts increases in regions where flow separation is intensified. Overall, these results advance the understanding of airflow structures around high-rise buildings and demonstrate that high-resolution Large-Eddy Simulation under extreme weather conditions can improve wind hazard assessment accuracy and support evidence-based decisions for pedestrian safety and urban resilience.

 

Keywords: Large-eddy simulation; CFD model; High-rise building; Gust; Typhoon landfall