Sensitivity of urban morphology and the number of CFD simulated wind directions on pedestrian wind comfort and safety assessments

Pedestrian wind comfort and safety are critical in urban design, especially as cities densify and climate change impacts intensify. While Computational Fluid Dynamics (CFD) simulations are increasingly used in these assessments, a universally agreed-upon number of wind directions for accurate results has yet to be established. This study addresses this gap by exploring the influence of urban morphology, characterized by different degrees of urbanization and building layouts, on the required number of wind directions for accurate assessments. Extensive CFD simulations were conducted in five geometrically diverse locations: Bryne, Oslo, London, Singapore, and New York. Pedestrian wind comfort maps were generated, and velocity amplification factor (VAF) dynamics were analyzed. The results suggest that urban complexity does not significantly affect the required number of wind directions for reliable assessments. The study provides practical guidance for selecting the number of wind directions based on the study's focus: a minimum of 8 for basic assessments, 24 for high-accuracy assessments, and at least 36 for safety-focused assessments. This research significantly contributes to urban planning and design, empowering stakeholders with valuable insights for shaping resilient and comfortable urban environments.