On the effect of the aspect ratio on flow and turbulence over a two-dimensional street canyon

This paper presents a water-channel simulation of flow and turbulence in the urban boundary layer. The goal is to assess the role played by the aspect ratio (AR) of the street canyon, assumed as an archetype for more complex and realistic urban fabrics. The physical model consists of a series of two-dimensional obstacles used to mimic a regular array of buildings. Velocity measurements are performed using image analysis. Results show a dependence of the mean velocity and turbulence parameters on AR. Attention is particularly focused on the turbulent kinetic energy and its production-advection-dissipation mechanisms that occur in the urban canopy.