Pollutant dispersion by tall buildings: laboratory experiments and Large-Eddy Simulation

Area of Science:

• Environmental Fluid Dynamics
• Urban Meteorology
• Computational Fluid Dynamics

Background:

• Urban environments feature complex airflow patterns influenced by building structures.
• Understanding pollutant dispersion is crucial for urban air quality management.
• Tall buildings significantly alter local wind fields and contaminant transport.

Purpose of the Study:

• To investigate pollutant dispersion around tall buildings in a low-rise urban setting.
• To validate the accuracy of Large-Eddy Simulation (LES) against physical water flume experiments.
• To assess the influence of scale, surrounding low-rise buildings, and source characteristics on dispersion.

Main Methods:

• Full-scale Large-Eddy Simulation (LES) of pollutant dispersion.
• Water flume experiments with Particle Image Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF).
• Comparative analysis of simulation and experimental data at various scales.

Main Results:

• LES and water flume results showed strong agreement, confirming methodology suitability.
• Tall buildings dominate local flow and rooftop shear layer development, affecting vertical fluxes.
• Rooftop shear layer showed insensitivity to model scale; surrounding low-rise buildings caused minor but notable offsets.

Conclusions:

• Both LES and water flume experiments are suitable for studying pollutant dispersion around urban building clusters.
• Tall buildings are primary drivers of altered flow dynamics and pollutant transport.
• Findings offer insights applicable to realistic urban pollutant dispersion scenarios.