Quadrant analysis of boundary layer above pitched and flat roofs

0343445 - ÚT 2011 RIV CZ eng J - Journal Article
Kellnerová, Radka - Kukačka, Libor - Jaňour, Zbyněk
Quadrant analysis of boundary layer above pitched and flat roofs.
Acta Technica CSAV. Roč. 54, č. 4 (2009), s. 401-413. ISSN 0001-7043
Institutional research plan: CEZ:AV0Z20760514
Keywords : street canyon * flat and pitched roofs * quadrant analysis
Subject RIV: DG - Athmosphere Sciences, Meteorology
http://journal.it.cas.cz

Boundary layer over two types of urban roughness in wind-tunnel is investigated. The roughness is composed from rows of street canyons with two shapes of roof— flat and pitched. Different roofs produce different internal boundary layers above canyons. A layer generated by pitched roofs, is significantly more turbulent since it provides a larger vertical variation for the wind passing above. Momentum flux and corresponding transport exhibits diverse development, extension and magnitude as well. Ventilation in streets is therefore distinct from each other. Flat roofs generate rather larger eddies in street canyon, which does not disturb the ventilation significantly. Adversely, geometry of pitched roofs enables to wind to attack on the core of recirculation zone and break it. Quadrant analysis is applied for vertical profiles and cross-sectional areas in canyons in order to detect a domination of sweep or ejection events and to find a linkage to the third moment of velocity for both cases.
Permanent Link: http://hdl.handle.net/11104/0185924