查看“︁斯特劳哈尔数”︁的源代码

[[Image:Srrrpd.png|thumb|right|300px|长圆柱绕流中[[雷诺数]]与斯特劳哈尔数的关系]]
'''斯特劳哈尔数'''（{{lang-en|Strouhal number}}）是[[流体力学]]中用来描述周期性[[非定常系統|非定常流动]]的一个[[无量纲数]]，以捷克物理学家{{le|文岑茨·斯特劳哈尔|Vincenc Strouhal}}的名字命名。斯特劳哈尔于1878年研究了{{le|旋涡脱落|Vortex shedding}}及其产生的风鸣声。<ref>Strouhal, V. (1878) [http://babel.hathitrust.org/cgi/pt?id=uc1.b4433702;view=1up;seq=230 "Ueber eine besondere Art der Tonerregung"] (On an unusual sort of sound excitation), ''Annalen der Physik und Chemie'', 3rd series, '''5''' (10) :  216–251.</ref><ref>{{cite book |last=White |first=Frank M. |title=Fluid Mechanics |url=https://archive.org/details/fluidmechanics0000whit_n8e9 |edition=4th |year=1999 |location= |publisher=McGraw Hill |isbn=978-0-07-116848-9 }}</ref>

斯特劳哈尔数的定义为：
:<math> \mathrm{St}= {f L\over U}, </math>

其中<math>f</math>为旋涡脱落的频率，<math>L</math>为特征长度（如[[水力直径]]为翼型厚度），<math>U</math>为[[流速]]。

在起伏飞行等情形下，常以振动幅度为特征长度。此时可以得到斯特劳哈尔数与{{le|简约频率|Reduced frequency}}之间的关系：
:<math> \mathrm{St}= {k a\over \pi c}, </math>

其中<math>k</math>为简约频率，<math>a</math>为起伏的振动幅度。

== 参考文献 ==
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* {{Cite journal | last1 = Taylor | first1 = Graham K. | last2 = Nudds | first2 = Robert L. | last3 = Thomas | first3 = Adrian L. R. | doi = 10.1038/nature02000 | title = Flying and swimming animals cruise at a Strouhal number tuned for high power efficiency | journal = Nature | volume = 425 | issue = 6959 | pages = 707–711 | year = 2003 | pmid = 14562101| pmc = |bibcode = 2003Natur.425..707T }}
* {{cite web | url = http://style.org/strouhalflight/ | title = The Strouhal Number in Cruising Flight | first = Jonathan | last = Corum | year = 2003 | postscript = – depiction of Strouhal number for flying and swimming animals | accessdate = 2012-11-13 | archive-date = 2012-08-30 | archive-url = https://web.archive.org/web/20120830041026/http://style.org/strouhalflight/ | dead-url = no }}
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{{流體力學中的無因次量}}

[[Category:流體力學中的無因次量]]