Large-Eddy Simulations on Indoor/Outdoor Air Quality Relationship in an Isolated Urban Building

The airflow, pollutant dispersion and penetration of outdoor pollutants indoor in an isolated urban building are investigated computationally. The computation involves solving the two-dimensional Navier — Stokes equations using large eddy simulations based on the Smagorinsky subgrid scale model. The simulations involve investigations of the phenomena of airflow and pollutant dispersion in both indoor and outdoor environments under different Reynolds numbers with distinct combinations of building height, floor height, and building width. Pollutants originate from outdoor, located at the datum level of the windward side of the building. The objective is to study how outdoor pollutants penetrate indoor and relate this pattern to different building geometric configurations. The gradual increase in Reynolds number significantly favors pollutant transportation into the indoor environment and thus eventually changes the indoor/outdoor (IO) air ratio. Moreover, the value of the IO air ratio is particularly found to be highly affected by building height due to the capability of climbing over and escaping from the roof of the building. Results also show that the IO air ratio is dependent on the position of the sampling, which has been ignored in many previous experimental works. The research work poses important questions of indoor air quality as well as field measurements of the IO parameter.