Exploring the influence of urban density and mountainous topography on local wind patterns: An experimental study of Hongkong, China

The urban wind flow of the canopy layer has a significant impact on the urban climate, as well as the ventilation, pollutant diffusion, and thermal comfort. Therefore, the related studies are gaining attention in the last decade. The purpose of this study is to figure out the impacts of urban morphology and mountain topography on the urban wind flow, taking the pedestrian level height of Hong Kong as an example. Three wind tunnel test series were conducted, exploring scenarios with/without proposed high-rise buildings, as well as urban areas in two large city centers with/without upstream mountain terrain. Results indicate a 300 m high-rise building affects wind flow up to approximately 125 m upstream, yielding a 12% of velocity increase. Street wind speed peaks when the approaching wind aligns within 25° of the street's orientation, with building height and deviation on street sides significantly impacting wind speeds compared to street width. Additionally, the results reveal that mountain height primarily influences the reduction of pedestrian-level wind velocity, with less effect from distance and mountain slope in relation to the urban area.