Investigation of flow visualization around linked tall buildings with circular sections

Abstract

This study investigated the wind environment around buildings by visualizing the wind flow patterns of linked buildings (LB), in which two buildings with circular sections are attached through linking members. Particle image velocimetry was used to measure the wind flows around LB models with different gap distances between the buildings. Proper orthogonal decomposition (POD) analysis was applied to identify velocity and vorticity patterns. The results showed that when the two buildings have a side-by-side arrangement (α=0o), and the gap distance is small, the POD using velocity indicates a single vortex street and biased flow in the gap, whereas that using vorticity suggests a contracted flow in the gap. When the gap distance is large, two independent vortex streets appear in the first mode of both POD, with the POD using vorticity confirming the presence of recirculation zones in the wake region. In a tandem arrangement (α=90o), the shear layer street occurring in the upstream building affects the entire LB system, and the POD analysis using vorticity shows that the shear layer cannot surround the downstream building if the gap distance is large. The link, gap distance, and elevation have little impact on the flow patterns when α=90o. However, these factors affect the flow patterns when α=0o. In addition, when the gap distance is equal to two-thirds of the building breadth and α=0o, the two shear layer streets joined behind the space between the two buildings and produced the maximum mean wind speed around the building compared to other cases.