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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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Quadrant analysis of turbulent pollution flux above the modelled street intersection
Kukačka, Libor ; Nosek, Štěpán ; Kellnerová, Radka ; Jurčáková, Klára ; Jaňour, Zbyněk
The objective of this experimental study is to determine processes of a vertical turbulent pollution transport above the X-shaped street intersection in an idealised symmetric urban area for several approach flow directions. An experimental set-up for simultaneous measurement of the flow velocity and the tracer gas con-centration in a high temporal resolution is assembled. Vertical turbulent scalar fluxes are computed from the measured data in a horizontal plane above the street intersection. The quadrant analysis was applied to the vertical turbulent pollution fluxes data. Events with dominant contribution to vertical turbulent pollution flux were detected. The mean duration, repetition frequency and the duration percentage were computed for these events. A strong influence of the approach flow direction on the type of dominant events and their characteristics was resolved.
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Průchod posivního polutentu idealizovanou městskou zástavbou
Bezpalcová, Klára ; Jaňour, Zbyněk ; Leitl, B. ; Schatzmann, M.
The regular obstacle array of the Mock Urban Setting Test (MUST) field site in the Utah West Desert has been replicated in the large boundary layer wind tunnel at Hamburg University. Dispersion from a point source within an idealised urban canopy for an oblique wind direction was a main focus of the wind tunel measurements. Two different methods were used to estimate the travelling time of a passive tracer through the array. The first evident method was based on a measured instantaneous behaviour of the plume while switching on and off thepassive pullant source; the second one used the spatial concentration correlation coefficients obtained from the simultaneous measurement at two positions. Different travelling time behaviour for the points situated along and perpendicular to the street canyons has been detected.
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