Measurements and numerical modeling of flow field and pollutant dispersion in areaway space

In residential building design, areaway can act as an open subsurface space to help improve the living environment in adjacent basement by natural ventilation. To study this particular ventilation phenomenon mainly driven by wind force, the first part of this paper presents an investigation of flow field and pollution dispersion inside areaway space based on a wind tunnel experiment. In the experiment, the measurement of mean velocity, turbulence and concentration as well as the flow visualization were carried out for a rectangular cavity-like areaway model with the width to height (w/h) ratio ranging from 0.3 to 1.0 and the influence of above-ground building has also been investigated. The experimental results reveal quite different airflow patterns characterized with unsteady vortex movement inside the areaway model, which indicates that the w/h ratio and the above-ground building are important factors for ventilating the areaway space. Furthermore, for the purpose of computational fluid dynamics (CFD) model validation, the experimental results of flow fields were compared with the simulation results. The areaway model of w/h = 1 was used for this study and the simulations were performed using large-eddy simulation (LES) and standard k-ε turbulence model. The numerical results show a good agreement with the experimental results when using LES with inflow turbulence. The further investigations with regard to the characteristics of flow field and pollutant removal as well as ventilation performance were also performed by LES.