Aerodynamic correlation and flow pattern of high-rise building with side ratio of 3:1 under twisted wind profile: A computational study

This study numerically investigates twisted-wind effect on aerodynamic correlation and flow pattern of high-rise building with 3:1 side ratio. Spatial-temporal correlation of aerodynamic forces and flow filed under conventional wind profile (CWP) and twisted wind profile (TWP) are comprehensively compared. Proper orthogonal decomposition (POD) is further employed to extract wake flow pattern and mode correlation. The results show that twisted-wind effect on building with long afterbody is unique. Specifically, compared with CWP, TWP augments mean wind loads in three perpendicular directions (e.g., CMx under TWP30 is increased by 60.56% compared to CWP). The original two vortex structures (i.e., leading-edge vortex shedding (LEVS) and trailing-edge vortex shedding (TEVS)) appearing in CWP transit to relatively weaker alternate-edge vortex shedding (AEVS) in TWP, thus, the fluctuating lateral base moment and torsional force are reduced by 30.60% and 28.24% respectively under TWP30 compared to CWP. Correlation of wind load components and correlation of layer force are significantly magnified because TWP intensifies vertical moment exchange and force coupling effect, this possibly results in stronger wind-induced responses. POD analysis reveals essential mechanism of twisted-wind effect and shows that flow pattern (i.e., energy proportion, dominant frequency, mode shape and mode corre-lation) is largely changed by TWP.