Chapter 1 Using CFD to Study Air Quality in Urban

The study of building effects on air quality has grown beyond stack plume downwash. The relative placement of air intakes and exhausts and cooling tower exhausts on buildings can significantly affect the indoor air quality. Earlier studies of effects on building air intakes have been limited to relatively simple situations, unable to treat the complex envelope of most buildings and building groups. Computational Fluid Dynamics (CFD) is becoming available as a tool to assist with modeling the airflow and dispersion of pollutants among complex urban geometries on the scale of a section of a building exterior up to several city blocks. This tool allows more accurate predictions of impacts over a range of meteorological scenarios and alternative building designs and placements relative to roadways and other pollutant sources. Recent projects are discussed to illustrate the capabilities of CFD in modeling urban microenvironments. The steps in a CFD application are presented including geometry and mesh creation, simulation of meteorological conditions, handling of pollutant sources, and post-processing visualization. The benefits and shortcomings of this approach are also discussed