Analysis of aerodynamic phenomena in selected quarter of building development in warsaw downtown with reference to air pollution

Air pollution, both gaseous and in the form of dust, is a problem that affects numerous densely built-up areas of modern cities. Based on this assumption, the authors of the following paper have examined an exemplary part of urban space with various building developments located in Warsaw downtown. Both experimental and numerical studies were conducted for the two prevailing wind directions observed in this area, that is the west wind and the south-west wind. Experimental research was conducted with the application of two known laboratory techniques, i.e., the oil visualization method and the sand erosion technique. The studies were conducted in an open-circuit wind tunnel. Commercial ANSYS Fluent program was used for numerical simulations. The k-e realizable turbulence model, often applied for this type of tasks, was used in the calculations. As a result, distributions of the velocity amplification coefficient were obtained in the area under consideration, as well as images that present the averaged airflow direction. On basis thereof, potential zones where contamination accumulation may occur were determined. The impact that introduction of a hypothetical high-rise building into the area would exert on wind conditions in its vicinity was also tested. High-rise buildings tend to intensify airflow in their immediate vicinity. Thus, they can improve ventilation conditions of nearby streets. However, in this particular case, the research prompted the conclusion that the proposed building causes turbulence and increased velocity gradients in the majority of elevation planes. On the other hand, in the ground-level zone, the building blocks rather than intensifies the airflow

The Problem of Airflow Around Building Clusters in Different Configurations

In the paper, the authors discuss the construction of a model of an exemplary urban layout. Numerical simulation has been performed by means of a commercial software Fluent using two different turbulence models: the popular k-ε realizable one, and the Reynolds Stress Model (RSM), which is still being developed. The former is a 2-equations model, while the latter – is a RSM model – that consists of 7 equations. The studies have shown that, in this specific case, a more complex model of turbulence is not necessary. The results obtained with this model are not more accurate than the ones obtained using the RKE model. The model, scale 1:400, was tested in a wind tunnel. The pressure measurement near buildings, oil visualization and scour technique were undertaken and described accordingly. Measurements gave the quantitative and qualitative information describing the nature of the flow. Finally, the data were compared with the results of the experiments performed. The pressure coefficients resulting from the experiment were compared with the coefficients obtained from the numerical simulation. At the same time velocity maps and streamlines obtained from the calculations were combined with the results of the oil visualisation and scour technique

Wind Conditions at Pedestrian Level in Different Types of Residential Urban Development for a High Degree of Land Use Efficiency

This paper addresses wind conditions in urban building development at the pedestrian level. The article aimed to identify aerodynamic phenomena around three types of multi-family housing developments with different forms and the same urban parameters of building development density (high density was taken into account). The aim of the research was mainly to achieve qualitative results that would lead to understanding fundamental processes and phenomena. Wind tunnel experimental studies were conducted on physical models at a scale of 1: 400 using visualization and erosion methods. These experiments yielded data regarding the arrangement of airflow directions and changes in airflow velocity, expressed as the amplification coefficient (α), the occurrence of which was caused by the presence of buildings. An analysis was conducted concerning wind conditions that constitute pedestrian comfort and influence the possibility for ventilation of spaces between buildings for the three selected models. The research results were compared, and an attempt was made to assess the most beneficial and the least favorable building development types in this respect