Experimental and Numerical Investigation of Air Cross-Contamination around Typical High-Rise Residential Building in Hong Kong

The dispersion of air pollutant in complex building environment has become of great concern for the modern society as more and more people live in large and crowded cities in many parts of the world. The primary aim of this work is to evaluate the risk of air cross-contamination around two typical forms of high-rise residential building in Hong Kong under two different naturally-ventilated conditions, i.e. buoyancy-dominated and wind-dominated conditions, respectively.;First a series of numerical studies were carried out to investigate the mechanism of contaminant transmission around one typical slab-shaped High-Rise Residential (HRR) building under the condition of single-sided natural ventilation. The results identified that the air pollutants can travel from a lower flat to an adjacent upper flat in the vertical direction through open windows caused by the indoor/outdoor temperature-difference induced buoyancy, revealing windows flush with the facade can be a major route of the air cross-contamination in HRR buildings. Also, the study attempted to evaluate the effectiveness of employing different optimal strategies in minimizing such cross contamination.;Subsequently, an experimental study was carried out to further investigate the dispersion characteristics around another typical complex-shaped building under wind effect. The experiments were performed in a boundary layer wind tunnel using tracer gas technique. The influenced region, the dispersion route, the strength of contaminant concentration and its exposure risks due to this kind of dispersion were thoroughly investigated under different circumstances. It was revealed both the mean and fluctuating concentrations should be paid attention to during the evaluation of the contamination risk. The experiment data were also used to evaluate the CFD methods, illustrating that CFD method with three kinds of k -- epsilon turbulence models is not recommended in predicting the near building pollutant dispersion.;The study on this physical process is not only helpful to reduce the hazardous effect of routine release of harmful indoor air pollutants, but also useful for the purpose of prevention and control of accidental infectious diseases outbreak. The features revealed by the investigation indicate that early intervention for high-rise residential blocks may be implemented in terms of diagnosis and isolation if an emerging, highly infectious disease is suspected.