Structure of a turbulent sevaration bubble

Masaru Kiya, Kyuro Sasaki

研究成果: ジャーナルへの寄稿記事

367 引用 (Scopus)

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Flow in the separation bubble formed along the sides of a blunt flat plate with right angled corners has been studied in terms of extensive single and two point measurements of velocity and surface pressure fluctuations. The cross correlations between the surface pressure and velocity fluctuations are found to be useful for the study of large scale vortex structure in the bubble. Large scale vortices are shed downstream from the separation bubble with a frequency of about 0.6U/xRwhere Uis the approaching velocity and xRis the time mean length of the bubble. On top of this regular vortex shedding, there exists a large scale unsteadiness in the bubble. Vortices which are much larger than the regular vortices are shed with frequencies less than about 0.2U/xR. The large scale unsteadiness is accompanied by enlargement and shrinkage of the bubble and also by a flapping motion of the shear layer near the separation line. The intermittent nature of the flow in the bubble is clarified in some detail. The distributions of the cross correlations between the pressure and velocity fluctuations demonstrate the vortex structure in the reattaching zone. The longitudinal distance between the vortices is estimated to be (0.7-0.8) xRand their convection velocity is about 0.5Unear the reattachment line. The cross correlations also suggest the existence of a longitudinal counter rotating system in the bubble. The distance between the axes of the rotation is of the order of 0.6xR. Variations of timescales, lengthscales and phase velocities of the vortices are presented and discussed.

元の言語英語
ページ(範囲)83-113
ページ数31
ジャーナルJournal of Fluid Mechanics
137
DOI
出版物ステータス出版済み - 1 1 1983
外部発表Yes

All Science Journal Classification (ASJC) codes

  • Fluid Flow and Transfer Processes
  • Engineering(all)

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