windy cities
Post on 30-Dec-2015
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Windy Citieshttp://www.youtube.com/watch?v=8NSW9R1IVAk
http://www.youtube.com/watch?v=SEBLt6Kd9EY
http://www.youtube.com/watch?v=porZ2jOaYew
Turbulence
http://www.youtube.com/watch?v=1jge03Qls6shttp://www.youtube.com/watch?v=HTOl0lTet9A
Turbulence is rotational, three dimensional air flow
Turbulence quickly turns the energy from moving air into heat
Unstable eddies in the wind which disrupt the flow of air
http://www.youtube.com/watch?v=5lSvDKv7sTg
http://www.youtube.com/watch?v=7HUUENCQFto
How does air Flow around Buildings?
Source of Dye Wind direction
Flow down Parallel StreetsSource www.dapple.org.uk
Wind Tunnel Experiments
flat roof H/W=0.6 flat roof H/W=1.0
high pitch H/W=0.6 high pitch H/W=1.0
Model scale ~ 1:400 ~ 400 times faster than in nature !!!
B. Blocken et al. / Environmental Modelling & Software 30 (2012) 15e34
Probability of Wind Nuisance at Eindhoven University
Hall to be replaced
Summary • Urban air flow is complicated!• Swirling flow is generated by buildings• At street level, the flow can even be in the
opposite direction to the wind higher up• There can be large gusts at street level which
can be annoying or even dangerous• Pollution can be concentrated in areas of low
wind speed.• Architects and urban planners try to design
buildings to maximise their natural ventilation, and to prevent dangerous air flow around them.
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