Influence of Building Shape on Wind-Driven Rain Exposure in Tall Buildings

Wind-driven rain (WDR) is a primary cause of material degradation in tall buildings that affects the durability and long-term performance. This study investigates the influence of building shape on WDR exposure in tall buildings using computational fluid dynamics (CFD) simulations. Results indicate that building shape influences local flow conditions, which, in turn, influence the trajectory of rain droplets and their impingement on building surfaces. Two specific flow features were found to dictate WDR exposure: the wind-blocking effect and the separation of shear layers at leading edges of the building. Streamlined geometries with small wind-blocking regions experienced higher WDR exposure on windward surfaces. High WDR concentrations also occurred on geometric features protruding into the wind and at locations where shear layers impinge on the building surface. These findings are based on steady Reynolds-Averaged Navier-Stokes (RANS) simulations that do not consider unsteady flow features such as buffeting and vortex shedding. Nonetheless, the study provides valuable insight into the influences of building shape on WDR exposure, which could lead to better weatherproofing of these buildings.