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Dependency of variable turbulent Schmidt numbers on building geometry, emission source, and inflow wind conditions of CFD simulation

par Weerasuriya, A.U.;Longo, Riccardo ;Zhang, Xuelin;Parente, Alessandro
Référence Journal of wind engineering and industrial aerodynamics, 274, 106490
Publication Publié, 2026-07-01

Article révisé par les pairs

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Résumé :

Variable turbulent Schmidt number (Sct) formulations estimate Sct based on ambient and local wind properties, which in turn are in a mixture of approaching and building-perturbed wind fields. This study investigated the dependency of variable Sct on approaching wind conditions, building geometries, and emission scenarios by conducting Computational Fluid Dynamics (CFD) simulations using the Reynolds-averaged Navier-Stokes equations and three variable Sct formulations. Four case studies include emissions near the ground, on a rooftop, and well above buildings, with varying ambient turbulence levels. Results showed that variable Sct yields more accurate air pollution predictions, particularly far downstream, compared to constant Sct. While variable Sct often reproduced dispersion patterns similar to a constant value of 0.7, it estimated mean Sct values ranging from 0.53 to 0.97. Variable Sct formulations with model parameters that depend on turbulence or flow properties estimated Sct in a wide range with sizable probabilities. In contrast, variable Sct formulations with fine-tuned model parameters led to lower variations around the mean Sct. Under high or low turbulence, variable Sct values deviate from the most common Sct of 0.7 and occasionally sensibly large Sct. Overall, variable Sct formulations demonstrated improved accuracy and adaptability over constant Sct in diverse turbulent flow scenarios.