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Flow dynamics and pollutant transport in street canyons of different roof heights and geometries: a wind tunnel and LES modelling
Kluková, Zuzana ; Jaňour, Zbyněk (advisor) ; Perret, Laurent (referee) ; Carpentieri, Matteo (referee)
Understanding the transfer of pollutants within complex urban areas is of utmost importance, but knowledge about it remains limited. This Thesis aims to investigate the characteristics of pollutant transfer, particularly flow dynamics, in six different street canyons integrated into an idealised built-up area consisting of blocks of buildings with courtyards. The systematic study was conducted to evaluate the impact of the following parameters on the ventilation of the street canyons: roof shape, building height non- uniformity and pollutant source position. Two complementary approaches are used in the study: wind-tunnel measurements and numerical modelling. In addition, a wide range of analytical methods are used, including reduced order methods such as Proper Orthogonal Decomposition (POD) and Oscillation Pattern Decomposition (OPD). It is shown that the OPD method provides valuable insights into the ventilation dynamics of street canoyns. The results demonstrate that all the parameters investigated have a significant impact on the ventilation, with roof shape playing a comparatively smaller role for non-uniform street canyons. All the methods applied have contributed to a better understanding of the observed processes while shedding light on the physical implications of the data decomposition methods by...
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Urban Ventilation Dependence on Geometric Configuration
Kukačka, Libor ; Jaňour, Zbyněk (advisor) ; Carpentieri, Matteo (referee) ; Uruba, Václav (referee)
Title: Urban Ventilation Dependence on Geometric Configuration Author: RNDr. Ing. Libor Kukačka Department: Department of Atmospheric Physics Supervisor: prof. RNDr. Zbyněk Jaňour, DrSc., Academy of Sciences of the Czech Republic, Institute of Thermomechanics, v. v. i. Abstract: The main goal of the thesis is to investigate the impact of urban geometry on the urban ventilation using wind-tunnel modelling. To measure the pollutant transport, both advective and turbulent, within complex urban geometries with a high temporal resolution a special measurement method was developed. At first, the pollution of a simplified urban area was simulated by a ground-level point source and the ventilation of the intersection with respect to four wind directions was studied. Later, the pollution of other simplified and complex urban areas was simulated by a ground-level line source and the ventilation of three different street canyons with respect to wind direction perpendicular and oblique to their along-canyon axis was investigated. The clear impact of urban complexity and wind direction on street canyon ventilation is demonstrated at lateral and top openings of all investigated canyons and the intersection. Whilst the dominance of the pollutant advection is demonstrated at the eaves of pitched roofs, at the roof ridges...
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Urban Ventilation Dependence on Geometric Configuration
Kukačka, Libor ; Jaňour, Zbyněk (advisor) ; Carpentieri, Matteo (referee) ; Uruba, Václav (referee)
Title: Urban Ventilation Dependence on Geometric Configuration Author: RNDr. Ing. Libor Kukačka Department: Department of Atmospheric Physics Supervisor: prof. RNDr. Zbyněk Jaňour, DrSc., Academy of Sciences of the Czech Republic, Institute of Thermomechanics, v. v. i. Abstract: The main goal of the thesis is to investigate the impact of urban geometry on the urban ventilation using wind-tunnel modelling. To measure the pollutant transport, both advective and turbulent, within complex urban geometries with a high temporal resolution a special measurement method was developed. At first, the pollution of a simplified urban area was simulated by a ground-level point source and the ventilation of the intersection with respect to four wind directions was studied. Later, the pollution of other simplified and complex urban areas was simulated by a ground-level line source and the ventilation of three different street canyons with respect to wind direction perpendicular and oblique to their along-canyon axis was investigated. The clear impact of urban complexity and wind direction on street canyon ventilation is demonstrated at lateral and top openings of all investigated canyons and the intersection. Whilst the dominance of the pollutant advection is demonstrated at the eaves of pitched roofs, at the roof ridges...
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