Numerical simulation of wind pressure distribution in urban buildings of random staggered arrays

Abstract

In typical urban areas where buildings are built in clusters, wind pressure distribution of buildings is influenced by the interference effects from neighbouring buildings, which consequently affect wind-induced ventilation in buildings. This study was aimed to investigate the relationship between two geometric parameters of idealized urban arrays and mean pressure distribution. Hence, numerical investigation was conducted using large-eddy simulation (LES) on six idealized urban cases. The first geometric parameter was packing density ƛp which is the ratio of planar area of buildings to the total surface area, and was used to designate six building arrays, between sparse and dense urban conditions i.e. 0.044 = ƛp = 0.391. The second geometric parameter was used to incorporate the heterogeneity of urban surfaces, defined by aspect ratio of building a (i.e. the ratio of frontal area to planar area of a building). Nine types of square-based buildings which were arranged randomly in staggered arrangement, have different values of a ranged between 0.84 (low-rise building) and 3.76 (high-rise building). Current results show that in denser arrays (i.e. ƛp = 0.250), pressure drag which was calculated through mean pressure differences between windward and leeward sides of buildings, is dominated by high-rise buildings by up to 55%. Besides, effects of packing density are significant on low-rise buildings (i.e. a = 2.64) since the interference effects are likely to intensify when distances between adjacent buildings become less mainly at height z below the building height average have. In addition, a linear relationship between a and averaged mean pressure difference is observed in all packing densities, particularly for high-rise buildings (i.e. a = 3). The results obtained from this study are exclusive to random staggered arrays, but the findings are an important addition to understanding wind pressure distribution in idealized arrays resembling real urban condition.