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Coherent structure of a d-type rough wall boundary layer by means of the four-quadrant analysis : low reynolds number effect

Memoirs of the Faculty of Engineering, Yamaguchi University Volume 45 Issue 1 Page 13-21
published_at 1994-10
KJ00000156989.pdf
[fulltext] 674 KB
Title
4象限分割法によるd形粗面境界層の組織構造の解析 : 低レイノルズ数の効果
Coherent structure of a d-type rough wall boundary layer by means of the four-quadrant analysis : low reynolds number effect
Creators Mochizuki Shinsuke
Creators Osaka Hideo
Source Identifiers
In order to investigate the low Reynolds number effect on the turbulent structure of a d-type rough wall boundary layer, fractional contribution of the stress generating motions to the Reynolds shear stress was qualitatively examined with the four-quadrant analysis. The second and forth quadrant events (ejections and sweeps) play major role in fractional contribution and also in intermittency through the layer. In the low Reynolds number flow fields, the second quadrant has dominant contribution to the Reynolds shear stress, while the contribution from the other three quadrants are reduced. Comparison of the ratio of fractional contribution from the second quadrant to that of the fourth quadrant among three types of surface, d-type rough, k-type rough and smooth, a certain difference of the near-wall turbnlent structure is found. It is expected that the difference can be explained with the dominant vortical structure. The violent ejections in the outer layer was investigated in detail. The mean frequency and conditional velocity patterns show that the violent ejections is associated with the large-scale spanwise vortical structure in the outerlayer and also the near-wall bursting phenomenon.
Languages jpn
Resource Type departmental bulletin paper
Publishers 山口大学工学部
Date Issued 1994-10
File Version Version of Record
Access Rights open access
Relations
[ISSN]0372-7661
[NCID]AN00244228
Schools 工学部