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Wind conditions and ventilation in high-rise long street models
2010 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 45, no 6, 1353-1365 p.Article in journal (Refereed) Published
Abstract [en]

We regarded high-rise cities as obstacles and channels to wind. We first studied wind conditions and ventilations in idealized high-rise long street models experimentally and numerically with a constant street width (W = 30 mm), variable street heights (H = 2 W, 2.5W, 3W, 4W), variable street lengths (L = 47.4W, 79W. 333W, 667W) and a parallel approaching wind. The flow rates penetrating into windward entries are a little larger than the reference flow rate in the far upstream free flow through the same area with windward entries in all models. The stream-wise velocity decreases along the street as some air leaves upwardly across street roofs. Near the leeward entry, there is a downward flow which brings some air into the street and results in an accelerating process. In the neighborhood scale long streets (L = 47.4W and 79W), wind in taller streets is stronger and the ventilation is better than a lower one. For the city scale long streets (L = 333W and 667W), a constant flow region exists where the vertical velocity is zero and the stream-wise velocity remains constant. In such regions, turbulent fluctuations across the street roof are more important to air exchange than vertical mean flows. In a taller street, the process to establish the constant flow conditions is longer and the normalized balanced horizontal flow rate is smaller than those in a lower street. In the city scale long streets, the turbulence exchange rate can be 5-10 times greater than the mean flow rate.

Place, publisher, year, edition, pages
2010. Vol. 45, no 6, 1353-1365 p.
Keyword [en]
Numerical simulation, Wind tunnel, High-rise long street, Flow rate, Air change rate (ACH), Turbulent exchange
National Category
Civil Engineering
URN: urn:nbn:se:kth:diva-46651DOI: 10.1016/j.buildenv.2009.11.019ISI: 000275515400001ScopusID: 2-s2.0-75949084439OAI: diva2:454768
QC 20111117Available from: 2011-11-08 Created: 2011-11-04 Last updated: 2011-11-17Bibliographically approved

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Sandberg, Mats
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