A review of investigating airflows around buildings

With the awareness of sustainability in the built environment, implementing natural ventilation to provide cooling has become revitalized. But maintaining a healthy indoor environment, especially for those high-rise residential buildings, could be an issue. The purpose of this review is to systematically review investigation methods (On-site measurements, physical scale modeling (wind tunnel and water channel experiments) and different computational fluid dynamics turbulence models (DNS, RANS and LES) for these practical concerns and knowledge gaps with regard to air flow around building and to indentify effective investigation methods with the ultimate goal to find optimum ventilation for HRR buildings. Physical scale modeling can be more controllable for airflow and building configurations, but the accuracies of them are still arguable. On-site measurement is a somewhat dear approach. Regarding to its accuracy, it still could under-predict the roof concentration. CFD is a fast, cost effective, risk reduction and safe method for examining the issue regarding to airflow and pollutant dispersion around the building. But the accuracies of each different turbulence model are different. DNS can provide the most accurate results in finite volume calculations; but it is impractical for simulations due to large computational requirements. LES can over-predict the lateral pollutant concentration in the wake region of the building and requires somewhat larger computational demand and times. Although RANS is the most commonly used model for pollutant dispersion and infection control issues, it over-predicts surface concentrations downwind of the sources. The research also discovered that the vertical cross contaminant dispersion has not been widely studied, especially on the high-rise buildings, and the concentration fluctuation rates in the unsteady atmospheric environment has been missed.