Mean Velocity Profile In The Vicinity Of A Building Within Urban Boundary Layer With High Density Of Buildings

For wind engineering applications in urban environments there is a need for a quick estimation of the mean wind velocity around buildings, e.g. in the case of predicting the energy output of small wind turbines mounted on building roofs. This paper presents the derivation of the analytical method for estimating the wind velocity above buildings in urban areas with high building density. This development is performed in three steps. In order to analyze the flow pattern in a typical urban geometry, the first step consisted of a series of CFD simulations, where typical urban configuration was assumed (specified building size and respective distances between the buildings) and varied with an incremental value, and for each analyzed configuration different incoming wind conditions (different reference wind velocities) were incrementally imposed. In the second step the velocity profiles in characteristic cut-lines around the central building under investigation were extracted from the respective CFD realizations, and analytical expression was derived approximating all extracted velocity profiles to fit the best an assumed flow pattern (logarithmic distribution within the internal urban boundary layer). Finally, in the third step the derived analytical expression was crossplotted with the results of a fully three-dimensional realistic urban flow numerical simulation, and the obtained matching level was satisfactory.