View source for Wind engineering

{{Short description|Study of the effects of wind on natural and built environments}}
[[File:Wind around house Barani Design.gif|thumb|upright=1.35|[[Flow visualization]] of wind speed contours around a house]]
[[File:Al Habtoor City - Noora Tower.jpg|thumb|upright=1.35|Wind engineering covers the aerodynamic effects of buildings]]
[[File:Hurricane Maria damaged wind turbines at Santiago y Lima in Naguabo, Puerto Rico.jpg|thumb|Damaged wind turbines due to hurricane Maria]]
'''Wind engineering''' is a subset of [[mechanical engineering]], [[structural engineering]], [[meteorology]], and [[applied physics]] that analyzes the effects of [[wind]] in the natural and the [[built environment]] and studies the possible damage, inconvenience or benefits which may result from wind. In the field of engineering it includes strong winds, which may cause discomfort, as well as extreme winds, such as in a [[tornado]], [[hurricane]] or [[Superstorm|heavy storm]], which may cause widespread destruction. In the fields of [[wind energy]] and [[air pollution]] it also includes low and moderate winds as these are relevant to electricity production and dispersion of contaminants.

Wind engineering draws upon [[meteorology]], [[fluid dynamics]], [[mechanics]], [[geographic information system]]s, and a number of specialist engineering disciplines, including [[aerodynamics]] and [[structural dynamics]].<ref>{{Cite journal|last=Hewitt|first=Sam|last2=Margetts|first2=Lee|last3=Revell|first3=Alistair|date=2017-04-18|title=Building a Digital Wind Farm|journal=Archives of Computational Methods in Engineering|volume=25|issue=4|language=en|pages=879–899|doi=10.1007/s11831-017-9222-7|issn=1134-3060|pmc=6209038|pmid=30443152}}</ref> The tools used include [[atmospheric model]]s, atmospheric boundary layer [[wind tunnel]]s, and [[computational fluid dynamics]] models.

Wind engineering involves, among other topics:
* Wind impact on structures (buildings, bridges, towers)
* Wind comfort near buildings
* Effects of wind on the ventilation system in a building
* Wind climate for wind energy
* Air pollution near buildings

Wind engineering may be considered by structural engineers to be closely related to [[earthquake engineering]] and [[explosion protection]].

Some sports stadiums such as [[Candlestick Park]] and [[Arthur Ashe Stadium]] are known for their strong, sometimes swirly winds, which affect the playing conditions.

==History==
Wind engineering as a separate discipline can be traced to the UK in the 1960s, when informal meetings were held at the [[National Physical Laboratory (United Kingdom)|National Physical Laboratory]], the Building Research Establishment, and elsewhere. The term "wind engineering" was first coined in 1970.<ref>{{Cite journal|last=Cochran|first=Leighton|last2=Derickson|first2=Russ|date=April 2011|title=A physical modeler's view of Computational Wind Engineering|journal=Journal of Wind Engineering and Industrial Aerodynamics|language=en|volume=99|issue=4|pages=139–153|doi=10.1016/j.jweia.2011.01.015}}</ref> [[Alan Garnett Davenport]] was one of the most prominent contributors to the development of wind engineering.<ref>{{Cite book|last=Solari|first=Giovanni|title=Wind Science and Engineering: Origins, Developments, Fundamentals and Advancements|date=2019|publisher=Springer International Publishing|isbn=978-3-030-18814-6|series=Springer Tracts in Civil Engineering|location=Cham|language=en|doi=10.1007/978-3-030-18815-3}}</ref> He is well known for developing the Alan Davenport wind-loading chain or in short "wind-loading chain" that describes how different components contribute to the final load calculated on the structure.<ref>{{Cite journal|last=Isyumov|first=Nicholas|date=May 2012|title=Alan G. Davenport's mark on wind engineering|journal=Journal of Wind Engineering and Industrial Aerodynamics|language=en|volume=104-106|pages=12–24|doi=10.1016/j.jweia.2012.02.007}}</ref>

==Wind loads on buildings==
[[File:Wind Tunnel Model of One Post Office Square, Boston, by Frank Durgin, model built by Earl Wassmouth, 1979, view 2 - MIT Museum - DSC03794.JPG|thumb|Wind Tunnel Model of One Post Office Square, Boston]]
The design of buildings must account for wind loads, and these are affected by [[wind shear]].
<!-- Note that although Wind loading exists, but is only a redirect back to this page. -->
For engineering purposes, a power law wind-speed profile may be defined as:<ref name=Crawley>{{cite book | last = Crawley | first = Stanley | title = Steel Buildings | publisher = Wiley | location = New York | year = 1993 | isbn = 978-0-471-84298-9 | pages = 272 }}</ref><ref name=Gupta>{{cite book | last = Gupta | first = Ajaya Kumar and Peter James Moss| title = Guidelines for Design of Low-Rise Buildings Subjected to Lateral Forces | publisher = CRC Press | location = Boca Raton | year = 1993 | isbn = 978-0-8493-8969-6 | pages = 49|url=http://www.crcpress.com/product/isbn/9780849389696}}</ref>

:<math>\ v_z = v_g \cdot \left( \frac {z} {z_g} \right)^ \frac {1} {\alpha}, 0 < z < z_g
</math>

where:

:<math>\ v_z</math> = speed of the wind at height <math>\ z</math>
:<math>\ v_g</math> = gradient wind at gradient height <math>\ z_g </math>
:<math>\ \alpha</math> = exponential coefficient
<br />
Typically, buildings are designed to resist a strong wind with a very long return period, such as 50 years or more. The design wind speed is determined from historical records using [[extreme value theory]] to predict future extreme wind speeds. Wind speeds are generally calculated based on some regional design standard or standards. The design standards for building wind loads include:
* AS 1170.2 for Australia
* EN 1991-1-4 for Europe
* NBC for Canada

==Wind comfort==
[[File:Wind Baffles, Water Lane, Leeds (37745389046).jpg|thumb|Wind baffles being installed to mitigate wind danger issues at the [[Bridgewater Place]] skyscraper in Leeds, UK]]
[[File:Ameristar 9363 hangar wind field.png|thumb|Computer simulation of the airflow downwind of a hangar which caused damage to [[Ameristar Charters Flight 9363]]]]

The advent of high-rise [[tower blocks]] led to concerns regarding the wind nuisance caused by these buildings to pedestrians in their vicinity.

A number of wind comfort and wind danger criteria were developed from 1971, based on different pedestrian activities, such as:<ref>[http://sts.bwk.tue.nl/urbanphysics/pdf/2013_BAE_WD_BB_TvH_Preprint.pdf Pedestrian wind comfort around buildings: comparison of wind comfort criteria. Table 3]</ref>
* Sitting for a long period of time
* Sitting for a short period of time
* Strolling
* Walking fast
Other criteria classified a wind environment as completely unacceptable or dangerous.

Building geometries consisting of one and two rectangular buildings have a number of well-known effects:<ref>[http://sts.bwk.tue.nl/urbanphysics/pdf/2013_BAE_WD_BB_TvH_Preprint.pdf Pedestrian wind comfort around buildings: comparison of wind comfort criteria. Figure 6]</ref><ref>[http://www.hkisc.org/proceedings/2006421/6_Johnny_Yu%20Wind%20Effect%20on%20Pedestrians.pdf Wind Effects On Pedestrians. Figure 3]</ref>
* Corner streams, also known as corner jets, around the corners of buildings
* Through-flow, also known as a passage jet, in any passage through a building or small gap between two buildings due to pressure short-circuiting
* Vortex shedding in the wake of buildings

For more complex geometries, pedestrian wind comfort studies are required.  These can use an appropriately scaled model in a boundary-layer [[wind tunnel]], or more recently,  use of [[computational fluid dynamics]]  techniques has increased.<ref>[http://www.aij.or.jp/jpn/publish/cfdguide/JWEIAguide.pdf AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings]</ref> The pedestrian level wind speeds for a given exceedance probability are calculated to allow for regional wind speeds statistics.<ref>[https://www.cmff.hu/oktatas/tantargy/NEPTUN/BMEGEATMW08/2010-2011-1/ea_lecture/blocken_pedestrianWindEnvironment.pdf Pedestrian Wind Environment Around Buildings. p112]</ref>

The vertical wind profile used in these studies varies according to the terrain in the vicinity of the buildings (which may differ by wind direction), and is often grouped in categories, such as:<ref>[https://law.resource.org/pub/nz/ibr/as-nzs.1170.2.2011.pdf AS/NZS 1170.2:2011 Structural Design Actions Part 2 – Wind actions. Section 4.2]</ref>
* Exposed open terrain with few or no obstructions and water surfaces at serviceability wind speeds
* Water surfaces, open terrain, grassland with few, well-scattered obstructions having heights generally from 1.5 to 10 m
* Terrain with numerous closely spaced obstructions 3 to 5 m high, such as areas of suburban housing
* Terrain with numerous large, high (10 to 30 m high) and closely spaced obstructions, such as large city centres and well-developed industrial complexes

==Wind turbines==

[[Wind turbine]]s are affected by wind shear. Vertical wind-speed profiles result in different wind speeds at the blades nearest to the ground level compared to those at the top of blade travel, and this, in turn, affects the turbine operation.<ref name=Heier>{{cite book | last = Heier | first = Siegfried | title = Grid Integration of Wind Energy Conversion Systems | publisher = John Wiley & Sons | location = Chichester | year = 2005 | isbn = 978-0-470-86899-7 | pages = 45}}</ref> The wind gradient can create a large bending moment in the shaft of a two bladed turbine when the blades are vertical.<ref>{{cite book | last = Harrison | first = Robert | title = Large Wind Turbines | publisher = John Wiley & Sons | location = Chichester | year = 2001 | isbn = 978-0-471-49456-0 | pages = 30}}</ref> The reduced wind gradient over water means shorter and less expensive wind turbine towers can be used in shallow seas.<ref name=Lubosny>{{cite book | last = Lubosny | first = Zbigniew | title = Wind Turbine Operation in Electric Power Systems: Advanced Modeling | publisher = Springer | location = Berlin | year = 2003 | isbn = 978-3-540-40340-1 | pages = 17}}</ref>

For [[wind turbine design|wind turbine engineering]], wind speed variation with height is often approximated using a power law:<ref name=Heier/>

:<math>\ v_w(h) = v_{ref} \cdot \left( \frac {h} {h_{ref}} \right)^ a
</math>

where:

:<math>\ v_w(h)</math> = velocity of the wind at height <math> h</math> <nowiki>[m/s]</nowiki>
:<math>\ v_{ref}</math> = velocity of the wind at some reference height <math> h_{ref} </math> <nowiki>[m/s]</nowiki>
:<math>\ a</math> = Hellman exponent (aka power law exponent or shear exponent) (~= 1/7 in neutral flow, but can be >1)

==Significance==
The knowledge of wind engineering is used to analyze and design all [[high-rise]] buildings, cable-[[suspension bridge]]s and [[cable-stayed bridge]]s, electricity transmission towers and [[telecommunication tower]]s and all other types of towers and chimneys. The wind load is the dominant load in the analysis of many tall buildings, so wind engineering is essential for their analysis and design. Again, wind load is a dominant load in the analysis and design of all long-span [[cable bridge]]s.

==See also==
* [[Hurricane engineering]]
* [[John Twidell]]
* [[Vibration control]]
* [[Wind tunnel]] testing
* [[World Wind Energy Association]]
* [[Damping]] 
* [[Alan G. Davenport]]

==References==
{{reflist}}

==Further reading== 
* {{Cite journal |last=Blocken |first=Bert |date=2014 |title=50 years of Computational Wind Engineering: Past, present and future |url=https://linkinghub.elsevier.com/retrieve/pii/S016761051400052X |journal=Journal of Wind Engineering and Industrial Aerodynamics |language=en |volume=129 |pages=69–102 |doi=10.1016/j.jweia.2014.03.008}}
* {{Cite journal |last=Baker |first=C.J. |date=2007 |title=Wind engineering—Past, present and future |url=https://linkinghub.elsevier.com/retrieve/pii/S0167610507000219 |journal=Journal of Wind Engineering and Industrial Aerodynamics |language=en |volume=95 |issue=9-11 |pages=843–870 |doi=10.1016/j.jweia.2007.01.011}}

==External links==
* {{cite web |title=How Tall Buildings Tame the Wind |work=The B1M |date=September 12, 2018 |url=https://www.youtube.com/watch?v=tHMPR7flpf4  |archive-url=https://ghostarchive.org/varchive/youtube/20211215/tHMPR7flpf4 |archive-date=2021-12-15 |url-status=live|via=[[YouTube]] }}{{cbignore}}

{{DEFAULTSORT:Wind Engineering}}
[[Category:Engineering disciplines]]
[[Category:Structural engineering]]
[[Category:Wind engineering]]
[[Category:Energy engineering]]
[[Category:Wind power]]