Validation of CFD simulations of turbulent air flow over a regular array of cubes with wind tunnel data and a 3D analysis of the flow

Air pollution in urban canopy represents an important environmental problem and the study of pollutant dispersion in cities is not easy. The interaction between atmospheric flow and urban obstacles such as buildings generates a complex flow in streets affecting pollutant dispersion. Useful tools to study building-air flow interactions are Computational Fluid Dynamics models (CFD). CFD model simulations play an important role in the understanding of microscale flow features and their results can be useful for urban parameterizations in high resolution mesoscale models. In this contribution, air flow over a regular array of cubes is simulated by a CFD. Simulation is based on Reynolds Averaged Navier-Stokes equations (RANS) using standard k-e turbulent closure. CFD results are validated against wind tunnel measurements. Some statistical parameters (correlation coefficients, fractional BIAS and normalised mean square error) are computed and a validation test is applied. Comparison shows that the complex flow structure over building array obtained by CFD is in good agreement with wind tunnel data. In addition, a three-dimensional analysis of the air flow structure inside street canyons is carried out.