An Applied Research To Forecast The Trend Of Air Pollution In Particular Geometries Of Streets: The Real Case Of Urban Canyon
Free (open access)
F. Patania, A. Gagliano, F. Nocera, A. Galesi & A. D’Amico
High pollution levels have often been observed in urban street canyons due to the increased traffic emissions and reduced natural ventilation. To investigate this phenomenon suitable microscale dispersion models must be used in order to give the right support to decision makers for air pollution control. Within these streets, pedestrians, cyclists, drivers and residents are likely to be exposed to pollutant concentrations exceeding current air quality standards. In this way people carried out an applied research choosing the \“V. Giuffrida” street of Catania as a test canyon because this street shows both geometric features typical of an urban canyon and a lot of car traffic flowing during all the day. In the first step the authors carried out preliminary and suitable studies about street and surrounding buildings geometries, meteoclimatic local data, intensity of traffic flow in different hours of day and so on. In the second step a computational model of the street canyon has been developed taking into account all blocks of buildings on each side of the street according to the actual urban situation. The computational model has been done using K–ε turbulence model and under three wind directions and velocity values characteristic of the area. Finally, people carried out a campaign of concentrations measurements of tracer gas on suitable sections of the investigated street. This paper intends to show: - the methodologies and techniques to draw the investigation with the backing of a 3D computer code suitable for this use (Airpak – Fluent in our case). - the particular flow-dynamic situations with formation of pollutant store zones. - the influence of both buildings geometry and the presence of internal courtyard on pollution profiles. - The distribution of gas concentrations along the facades of buildings flanking the street with reference to those zones which, overcoming the alarm limits of law, can cause detrimental effects on the health of the inhabitants. Keywords: urban canyons, air pollution, urban traffic.
urban canyons, air pollution, urban traffic.