Evaluating effects of building clusters on airflow and pollutant dispersion

Tall buildings are changing the air we breathe. The sizes and shapes of buildings, the layout of highways and streets, the placement of bridges and tunnels, all work to create vortices and jets that affect airflow and pollutant dispersion. Properly evaluating airflow through a city requires understanding the effects of clusters of buildings and the gaps between them.

Fu et al. used computational models to do just that, employing large-eddy simulations and bi-directional extended proper orthogonal decomposition (EPOD) to capture details of turbulent structures and flows between high-rises.

Their simulations produced clear depictions of the effects of building gaps, even identifying subtle differences in airflow between gaps of different sizes. Their bi-directional EPOD model revealed patterns in turbulent structures created by building formations and their impacts on pollutant transport.

“Larger gaps create powerful, stable jets that carve out distinct vortex structures, while smaller gaps lead to chaotic, high-frequency fluctuations,” said author Bingchao Zhang. “These interactions shape the dispersion and accumulation of pollutants, painting a complex picture of urban air dynamics.”

By understanding how building placement affects the movement of airborne pollutants, the authors hope to guide urban planners and policymakers to design better cities.

“Imagine urban layouts that harness the power of wind to whisk away pollutants, creating healthier, more vibrant environments,” said Zhang. “Strategically mixing and arranging large and small gaps could be the key to unlocking dynamic airflow patterns that improve air quality.”

Next, the researchers plan to explore more complex building configurations and incorporate more physical conditions into their simulations to further improve their results.

Source: “Gap flow dynamics and air pollutant dispersion mechanism behind building clusters,” by Yunfei Fu, Yunlong Wang, Peizhen Yang, Yaohan Li, Haiqing Liu, Tim K. T. Tse, Cruz Yutong Li, Kan He, and Bingchao Zhang, Physics of Fluids (2025). The article can be accessed at https://doi.org/10.1063/5.0255849 .