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DNS of heat transfer increase in a cylinder stagnation region due to wake-induced turbulence

Venema, L.; Terzi, D. von; Bauer, H.-J.; Rodi, W.

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 polluta ... mehr


Zugehörige Institution(en) am KIT Institut für Hydromechanik (IFH)
Institut für Thermische Strömungsmaschinen (ITS)
Publikationstyp Zeitschriftenaufsatz
Jahr 2011
Sprache Englisch
Identifikator DOI: 10.1016/j.ijheatfluidflow.2011.03.003
ISSN: 0142-727X
KITopen ID: 1000032020
Erschienen in International Journal of Heat and Fluid Flow
Band 32
Heft 3
Seiten 492-498
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