Wind-tunnel estimation of mean and turbulent wind speeds within canopy layer for urban campus

Abstract

The aim of this study was to clarify the effects of high-rise buildings on the mean and turbulent wind speeds within the canopy layer of an urban university campus in Malaysia. We investigated the characteristics of both mean and exceeding wind speeds by deriving probability density functions of wind speed at a selected canopy height. First, mean wind speeds were compared with those predicted by several existing models as a function of building morphological parameters. Although all empirical models predicted wind speed decreases with an increase in building density, the predicted values and our experimental data did not agree. These results imply that existing prediction models exhibit limitations in specific urban morphologies. Second, the derived probability density functions approached the normal distribution when mean wind speeds increased. In addition, peak factors of wind speeds within the canopy layer approached the values determined by the normal distribution when the mean wind speed ratios were larger than 0.5. These results indicated that strong wind speeds can be predicted by the peak factor of the normal distribution regardless of the location or wind direction using the provided mean wind speed and standard deviations of the mean when wind ratios are larger than 0.5.