Building porosity for better urban ventilation in high-density cities - A computational parametric study

Area of Science:

• Urban climatology and microfluid dynamics.
• Computational fluid dynamics (CFD) applied to urban environments.

Background:

• Compact urban building forms generate significant frictional drag, impeding airflow within the urban boundary layer.
• Stagnant air conditions in subtropical urban areas, particularly during summer, exacerbate outdoor thermal discomfort.

Purpose of the Study:

• To adapt and validate the kappa-omega SST turbulence model for simulating urban airflow.
• To assess the impact of wind speed, classified by Physiological Equivalent Temperature (PET), on outdoor thermal comfort.
• To investigate the effects of building morphology modifications on pedestrian-level natural ventilation.

Main Methods:

• Validation of the kappa-omega SST turbulence model against wind tunnel experimental data for airflow around a rectangular block.
• Computational parametric study involving wind speed classification based on PET.
• Numerical analysis of building morphology variations to evaluate their influence on natural ventilation.

Main Results:

• The kappa-omega SST model accurately simulates airflow around urban structures.
• Wind speed significantly influences pedestrian-level thermal comfort, with specific classifications derived from PET.
• Building porosity modifications demonstrate potential for enhancing natural ventilation at the pedestrian level.

Conclusions:

• The validated kappa-omega SST model provides an accurate and practical tool for urban airflow simulation.
• Optimizing building porosity is crucial for improving pedestrian-level urban ventilation and thermal comfort.
• Findings offer actionable insights for city planners and architects to enhance urban microclimates without compromising land use.