Simulation and Validation of CFD turbulent air flow at pedestrian level using 3D ultrasonic anemometer in the controlled urban area "Sense-City"
Résumé
Computational Fluid Dynamics (CFD) is increasingly used to describe the airflow in urban environments. In this study, we aim to simulate and to validate the airflow in a full-scale urban area submitted to controlled climatic conditions through an impressive climatic chamber. This non-standard equipment named 'Sense-City' is made up of a 400 m2 realistic district with buildings and street layout. The Sense-City urban area is highly instrumented, which allows notably the validation of physical models and simulations and the test of innovative urban solutions. Using a URANS model, with the k-omega SST model as the closure model, a CFD analysis is made on the turbulent airflow in Sense-City at a reasonable computational cost. The simulated velocities and turbulent kinetic energy are compared with measurements collected at a pedestrian level using a 3D ultrasonic anemometer. We show that the numerical simulations correctly predict the flow direction and flow characteristics such as dead flow zones, i.e. almost null flow velocity areas. Geometry simplifications, uncertainties on the boundary conditions and the use of a coarse mesh and time discretization to fulfill operational purposes have led to a Root Mean Square Error (RMSE) score of 0.26 m/s on the velocity magnitude.
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