A LABORATORY INVESTIGATION OF FLOW AND TURBULENCE OVER A TWODIMENSIONAL URBAN CANOPY

A neutral boundary layer was reproduced in the laboratory to analyse the wind field in correspondence of a two-dimensional array of buildings. The study has been conducted in a water channel. The measurements were performed along a vertical plane, parallel to the streamwise velocity and perpendicular to the obstacles. The goal was to examine in detail how the aspect ratio AR=W/H influences the velocity field (here H is the building height and W the road width). In particular, an analysis of the mean velocity, turbulent kinetic energy, Reynolds stress, skewness factor, production of the turbulent kinetic energy and its rate of dissipation is conducted for AR ranging from 1 to 2. Particular attention is focused on the Reynolds stress, one of the parameters mostly affected by the aspect ratio.