Atmospheric boundary layer over urban roughness: validation of large-eddy simulation
The study presents wall-modeled large-eddy simulations (LES) characterizing the flow features of a neutral atmospheric boundary layer over two urban-like roughness geometries: an array of three-dimensional square prisms and the “Michel-Stadt” geometry model. The former is an arrangement of idealized...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/433016 |
| Acceso en línea: | https://hdl.handle.net/2117/433016 https://dx.doi.org/10.1063/5.0265556 |
| Access Level: | acceso abierto |
| Palabra clave: | Atmospheric dynamics Turbulence simulations Turbulent flows Àrees temàtiques de la UPC::Física::Física de fluids |
| Sumario: | The study presents wall-modeled large-eddy simulations (LES) characterizing the flow features of a neutral atmospheric boundary layer over two urban-like roughness geometries: an array of three-dimensional square prisms and the “Michel-Stadt” geometry model. The former is an arrangement of idealized building blocks and incorporates a 7x7 array of wall-mounted prisms with identical spacing ratios in both transversal and longitudinal directions. The latter mimics a typical central European urban geometry, which presents spatial inhomogeneity in all directions. In both cases, the incident wind angle is 0°. The Reynolds numbers for each case are Reh = 5.0*10^6 and 8.0*10^6¿, respectively (¿ Reh = Uref*H/v with Uref and H denoting the reference velocity and building height, respectively, and v the kinematic viscosity). The LES employs a high-order, low-dissipation numerical scheme with a spatial resolution of 0.75¿m within the urban canopy. An online precursor simulation ensures realistic turbulent inflow conditions, improving the accuracy of the results. The simulations performed successfully capture mean-velocity profiles, wake regions, and rooftop acceleration, with excellent agreement in the streamwise velocity component. While turbulent kinetic energy is well predicted at most locations, minor discrepancies are observed near the ground, partially due to insufficient near-wall resolution and measurement constraints. The analysis of scatter plots and validation metrics (FAC2 and hit rate) shows that LES predictions outperform the standard criteria commonly used in urban flow simulations, while spectral analysis verifies that LES accurately resolves the turbulent energy cascade over approximately two frequency decades. The Kolmogorov -2/3 slope in the pre-multiplied spectra has been well reproduced below and above the urban canopy. These findings reinforce the importance of spectral analysis in LES validation and highlight the potential of high-order methods for LES of urban flows. |
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