Hurricane Boundary Layer Turbulence Dynamics Over Complex Urban Canopies Using Large‐Eddy Simulations

Abstract

Hurricanes cause severe damage and destruction when striking densely populated urban areas. However, the impacts of buildings on hurricane turbulence dynamics remain poorly understood due to limited high‐resolution simulations. This study aims to address this gap by resolving turbulent flows around buildings using large‐eddy simulation (LES) with immersed boundary method. Eleven high‐resolution LESs were conducted across a range of urban layouts, spanning flat, sparse, and dense canopies as well as low‐rise, staggered, and high‐rise configurations. First, the code was validated in a realistic configuration against measurements in Houston. Then, idealized runs were performed to characterize hurricane boundary layer (HBL) dynamics and distinguish them from non‐cyclonic atmospheric boundary layer (ABL) flows. Building height, spatial arrangement, and canopy density were shown to strongly influence wind dynamics, turbulence, and aerodynamic roughness length, with staggered dense canopies generating the greatest drag and wake turbulence. These results offer reliable benchmarks for modeling hurricane winds over cities within a roughness Reynolds number (Re∗) range of ∼104–106, beyond oversimplified urban parameterizations. HBL‐ABL comparisons show that hurricane rotation, characterized by Rossby (Ro) number, suppresses turbulence and eddy viscosity, and amplifies mean winds, doubling drag on tall buildings and invalidating the assumption that hurricanes behave like stronger ABL winds. Spectral, turbulence budget, and spatial correlation analyses further demonstrate that centrifugal forces and urban roughness break down large coherent eddies and alter their orientation. These findings provide new insights into hurricane rotational dynamics and urban canopy morphology, enabling improved hurricane forecasts of weather models over complex urban terrains.