Effects of a solid tower and urban area on measured wind data: numerical and wind-tunnel simulations

Abstract

The wind speeds recorded since 1997 at a height of 318 m from anemometers mounted on the Sky Tower in Auckland, New Zealand, are the focus of this study. Mean and gust speeds have been measured by two anemometers, one mounted out from the North-West side and the other out from the South-East side. The tower and the surrounding buildings affect the measurements of the anemometers when the air blows from some certain directions. In this study, numerical and wind-tunnel simulations have been carried out to find directional correction factors to apply to the 20 years of data. Then, the homogenised wind data will later be used for meteorological and urban studies to determine wind structure characteristics, which will be compared to expected values and those available from anemometers at lower levels. The numerical and windtunnel models have been simulated at full- and 1:300 scales, respectively. Transient Hybrid RANS/LES model has been used in the CFD simulation. Good agreement was found between the CFD predictions and wind-tunnel results. Correction factors, compensating for the effects of the tower, were obtained for mean and gust wind speeds when wind blows from the 8 cardinal directions.