Power law model for wind profiles correction in urban environment

Wind speed correction based on the terraincharacteristics is commonly found in severalwind related applications in the builtenvironment. In some models based on powerlaw profile, the exponent (a) and a correctionfactor (1) are assumed for each tewain type.This paper aims to check the applicability ofone of these models for urban environmentswith high density. Experiments in a boundarylayer wind tunnel were performed for an urbanarea of 600 x 600 m, in the district of Moema,in the city of S5o Paulo, Brazil, using a modelwith 1:500 scale. The test was performed forone predominant wind direction (SE), and thewind profile in the upstream presentedexponent of 0.15. The wind profile wasmeasured in 6 points in the scale model using1 D hotwire probe. The predicted profile usingthe BS5925: 1991 method and the measuredprofiles were compared, and the empiricalcoefficients (a and k) were recalculated whenthe results are not in agreement. Therecalculated exponent for the area is 0.58,which is much higher than the valueprescribed by BS5925 for the "City" terraintype. The wind profile vertical displacementdue to the high urban density is not taken intoaccount in the BS5925, but the wind tunneltests presented values of 60 m for thedisplacement. The paper concludes that thevertical displacement is the main sowce oferrors in the correction of the wind profile.