Scalar Fluxes Near a Tall Building in an Aligned Array of Rectangular Buildings

Area of Science:

• Environmental fluid dynamics
• Atmospheric dispersion modeling
• Urban meteorology

Background:

• Ground-level scalar dispersion in urban environments is complex due to building geometry.
• Street canyons significantly alter airflow and pollutant transport.
• Understanding dispersion patterns is crucial for air quality management in cities.

Purpose of the Study:

• To investigate scalar dispersion from ground-level sources in uniform and non-uniform building arrays.
• To analyze the impact of building height variations and wind direction on dispersion patterns.
• To quantify the contributions of advective and turbulent fluxes to scalar transport.

Main Methods:

• Wind-tunnel measurements were conducted on building arrays.
• Large-eddy simulation (LES) was employed to model scalar dispersion.
• Vertical scalar fluxes were decomposed into advective and turbulent components.

Main Results:

• Turbulent scalar fluxes were dominant in uniform-height building arrays.
• A tall building increased advective scalar fluxes, making them the dominant component.
• The presence of a tall building could either increase or decrease total vertical scalar flux based on source location.

Conclusions:

• Building arrays and tall structures significantly influence scalar dispersion patterns.
• Advective transport becomes more important in the presence of tall buildings.
• Findings can inform improved parameterizations for urban dispersion models, especially in complex urban topographies.