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The DNS consist of two series of runs; one is with kmax\u03b7 ~ 1 (Series 1) and the other is with kmax\u03b7 ~ 2 (Series 2), where kmax is the maximum wavenumber and \u03b7 the Kolmogorov length scale. The maximum Taylormicroscale Reynolds number R\u03bb in Series 1 is about 1130, and it is about 675 in Series 2. Particular attention is paid to the possible Reynolds number (Re) dependence of the statistics. The visualization of the intense vorticity regions shows that the turbulence field at high Re consists of clusters of small intense vorticity regions, and their structure is to be distinguished from those of small eddies. The possible dependence on Re of the probability distribution functions of velocity gradients is analysed through the dependence on R\u03bb of the skewness and flatness factors (S and F). 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Smallscale statistics in highresolution direct numerical simulation of turbulence: Reynolds number dependence of one point
http://hdl.handle.net/2237/11132
6229be10507945e4b1638ed7cec4dfda
名前 / ファイル  ライセンス  アクション  

download.pdf (1.5 MB)


Item type  学術雑誌論文 / Journal Article(1)  

公開日  20090217  
タイトル  
タイトル  Smallscale statistics in highresolution direct numerical simulation of turbulence: Reynolds number dependence of one point  
著者 
ISHIHARA, T
× ISHIHARA, T× KANEDA, M× YOKOKAWA, K× ITAKURA, K× UNO, A 

抄録  
内容記述  Onepoint statistics of velocity gradients and Eulerian and Lagrangian accelerations are studied by analysing the data from highresolution direct numerical simulations (DNS) of turbulence in a periodic box, with up to 40963 grid points. The DNS consist of two series of runs; one is with kmaxη ~ 1 (Series 1) and the other is with kmaxη ~ 2 (Series 2), where kmax is the maximum wavenumber and η the Kolmogorov length scale. The maximum Taylormicroscale Reynolds number Rλ in Series 1 is about 1130, and it is about 675 in Series 2. Particular attention is paid to the possible Reynolds number (Re) dependence of the statistics. The visualization of the intense vorticity regions shows that the turbulence field at high Re consists of clusters of small intense vorticity regions, and their structure is to be distinguished from those of small eddies. The possible dependence on Re of the probability distribution functions of velocity gradients is analysed through the dependence on Rλ of the skewness and flatness factors (S and F). The DNS data suggest that the Rλ dependence of S and F of the longitudinal velocity gradients fit well with a simple power law: S ~ −0.32Rλ0.11 and F ~ 1.14Rλ0.34, in fairly good agreement with previous experimental data. They also suggest that all the fourthorder moments of velocity gradients scale with Rλ similarly to each other at Rλ > 100, in contrast to Rλ < 100. Regarding the statistics of time derivatives, the secondorder time derivatives of turbulent velocities are more intermittent than the firstorder ones for both the Eulerian and Lagrangian velocities, and the Lagrangian time derivatives of turbulent velocities are more intermittent than the Eulerian time derivatives, as would be expected. The flatness factor of the Lagrangian acceleration is as large as 90 at Rλ ≈ 430. The flatness factors of the Eulerian and Lagrangian accelerations increase with Rλ approximately proportional to RλαE and RλαL, respectively, where αE ≈ 0.5 and αL ≈ 1.0, while those of the secondorder time derivatives of the Eulerian and Lagrangian velocities increases approximately proportional to RλβE and RλβL, respectively, where βE ≈ 1.5 and βL ≈ 3.0.  
内容記述タイプ  Abstract  
出版者  
出版者  Taylor & Francis  
言語  
言語  eng  
資源タイプ  
資源タイプresource  http://purl.org/coar/resource_type/c_6501  
タイプ  journal article  
ISSN  
収録物識別子タイプ  ISSN  
収録物識別子  00221120  
書誌情報 
Journal of Fluid Mechanics 巻 592, p. 335366, 発行日 200712 

フォーマット  
application/pdf  
著者版フラグ  
値  publisher  
URI  
識別子  http://hdl.handle.net/2237/11132  
識別子タイプ  HDL 