Effects of twisted wind flows on wind conditions in passages between buildings

The hilly terrain in Hong Kong detour winds and generate twisted wind profiles, which have varying wind directions along the profile's height. Twisted winds considerably influence the wind environments in built-up areas. Particularly the wind conditions around building arrays have paramount importance in Hong Kong as most of the building arrays are closely-spaced tall residential towers with some recreational areas located at buildings’ lower levels. This paper aims at the systematic investigation of the surrounding wind conditions of building arrays in twisted wind flows by a series of wind tunnel tests. There were 9 building models with different heights and passage widths tested in two twisted wind profiles at a number of wind incidence angles. Each model had three identical buildings and two similar passages among buildings. The observed wind environments in twisted wind flows were asymmetric near building arrays and wind speeds were dissimilar in the two passages. Compared to the building height, the passage width has more significant influences on wind conditions in passages in twisted wind flows. The effective wind direction, which is the vector summation of wind twist and wind incidence angle, is important in understanding the influence of approaching wind directions of twisted wind flows.