Impact of Wind Direction on Flow Over a Realistic Urban Area: A Large-Eddy Simulation Study

We conducted high-resolution large-eddy simulations over a real urban district in Barcelona to examine the impact of wind direction on near-ground flow. The computational mesh resolves over 500 million degrees of freedom, with a spatial resolution on the order of 1 m at pedestrian level. This allows a detailed analysis of mean velocity and turbulence patterns within the canopy layer. Although instantaneous flow fields differ significantly between cases, double-averaged profiles of velocity and turbulence intensity remain remarkably consistent across all wind directions. The results reveal a shear-driven mixing layer below the average building height and turbulence maxima near the tallest buildings, highlighting the influence of urban morphology on the development of flow and turbulence.