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Mass transport in shallow turbulent wake flow by planar concentration analysis

Carmer, C. F. von; Rummel, A. C.; Jirka, G. H.

Abstract:

Wind-tunnel studies of dispersion processes of traffic exhaust in urban street canyons with tree planting were performed and tracer gas concentrations using electron capture detection (ECD) and flow fields using laser Doppler velocimetry (LDV) were measured. It was found that tree planting reduce the air exchange between street canyons and the ambience. In comparison to treeless street canyons, higher overall pollutant concentrations and lower flow velocities were measured. In particular, for perpendicular approaching wind, markedly higher concentrations at the leeward canyon wall and slightly lower concentrations at the windward canyon wall were observed. Furthermore, a new approach is suggested to model porous vegetative structures such as tree crowns for small-scale wind-tunnel applications. The approach is based on creating different model tree crown porosities by incorporating a certain amount of wadding material into a specified volume. A significant influence of the crown porosity on pollutant concentrations was found for high degrees of porosity, however, when it falls below a certain threshold, no further changes in pollutant concentrations were observed.


Zugehörige Institution(en) am KIT Institut für Hydromechanik (IFH)
KIT-Zentrum Klima und Umwelt (ZKU)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2009
Sprache Englisch
Identifikator ISSN: 0733-9429
KITopen-ID: 1000032013
Erschienen in Journal of Hydraulic Engineering
Verlag American Society of Civil Engineers (ASCE)
Band 135
Heft 4
Seiten 257-270
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