Modeling Outdoor Air Pollution and the Urban Form

Abstract

As cities continue to grow rapidly, air pollution is becoming an increasing health problem. However, air pollution’s spatial and temporal variability make it difficult to quantify, even with field measurements. Models are thus useful to understand how pollutants interact with the built and natural environment. Computational fluid dynamics (CFD) offers the highest spatial and temporal resolution for aerial pollutant dispersion modeling within dense urban environments such as urban canyons. An open-source platform such as OpenFOAM is valuable as it can be fully customized for the varying intricacies of urban airflow and is accessible to a wide audience. This thesis develops a solver for aerial pollutant transport by adding a passive-scalar transport equation to buoyantBoussinesqPimpleFoam, the OpenFOAM transient solver for buoyant, turbulent flow of incompressible fluids, with Reynolds Averaged Navier-Stokes (RANS) turbulence modeling. It then demonstrates that this solver can be applied to cases, such as that of an urban canyon, with geometry generated parametrically using Grasshopper, a design tool commonly used by architects and urban designers. The successful implementation of this solver could enable future integration into a streamlined Grasshopper tool that allows designers to easily evaluate the impacts of their designs on urban air pollution during the design process.