Large-scale Stereo-PIV measurement of the flow inside an urban street canyon in outdoor conditions
Résumé
More than 50% of the worlwide population are city dwellers, this percentage reaching up to 80% in Europe. Urban heat island effect and global climate change are therefore expected to put the population at stress, with well-being or health related issues. In this contibution, we propose to investigate the wind field in a model urban environment in outdoor conditions. Atmospheric flows in urban environments are complex (3D and turbulent). Field measurement techniques such as particle image velocimetry (PIV) can bring valuable information, in comparison with usual pointwise sensors such as sonic anemometers. In this contribution, large scale stereoscopic PIV measurements are undertaken in a 2m by 2m cross section of an outdoor Canyon street at the 1 : 5 scale. Handling fluctuating wind conditions, achieving sufficient seeding, and coping with natural light are important challenges for the PIV technique in outdoor environments. Several datasets could be acquired with a good global datarate, under various conditions of wind directions and convection regimes. The analysis of mean velocity fields reveals the influence of thermal effects near the building walls on the flowfield. The conditions of appearance of a windwise vortex in the cross section of the street are also discussed.
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