Wind-comfort assessment in cities undergoing densification with high-rise buildings remediated by urban trees
Aytaç Kubilay, A. G. Rubin, Dominique Derome, Jan Carmeliet
Abstract
As cities are densified, the presence of high-rise buildings can deteriorate wind-comfort conditions in urban neighborhoods with low-rise buildings. The present study aims to determine critical heights above which the pedestrian wind comfort deteriorates. Wind-flow patterns around high-rise buildings are investigated in different idealized configurations based on a systematic parametric study using computational fluid dynamics (CFD) simulations. The impact of trees around high-rise buildings is quantified as a potential measure to reduce wind speed. As a further step, amplification factors obtained from CFD simulations are combined with available city-wide statistical data to obtain wind-comfort prediction maps. The results show that pedestrian wind comfort can worsen severely with a high-rise building exceeding two times the height of surrounding buildings. Above four times the height, any arrangement of surrounding buildings yields similar conditions in areas in close proximity to the high-rise building. However, the arrangement of buildings defines the overall wind-flow pattern. In staggered arrangement, in case of very tall buildings, critical corner streams are observed around neighboring buildings downstream. Large trees can reduce average wind speed, but they have only limited impact on the accelerated flow around the corners due to downflow from the high-rise building.