Spatiotemporal correlations of aerodynamic load and flow structures of buildings with different heights exposed to twisted wind profile

This study systematically investigates the spatial-temporal correlation of aerodynamic characteristics of buildings with different heights specifically for twisted wind. Surface pressure and flow field of square cross-section buildings with aspect ratio (AR=1:1, 1:4 and 1:6) under conventional wind profile (CWP) and twisted wind profile (TWP) are quantitatively measured by wind tunnel test and Large-eddy simulation. The correlation of wind loads and flow structures in time-frequency domain is examined. The results show that TWP largely modifies correlation of aerodynamic characteristics both spatially and spectrally, and this effect is dependent on the aspect ratio. For tall building, out-of-plane and in-plane correlation analysis indicates wake vortex under TWP results in stronger moment exchange along building height. Yet, TWP suppresses all correlations associated with Karman vortex. For low-rise building, TWP is more resembling the condition of CWP with certain attack angle. Thus, its correlation of wind load under TWP is amplified along all building height. Proper orthogonal decomposition (POD) analysis is further utilized to capture coherent structure and the spatial-temporal features of its correlation, which is expected to explain the potential mechanism of twisted-wind effect on correlation of wind load.