Development of Wall Turbulence in Blasius Flow
The subcritical transition in Blasius flow is examined experimentally through observing its response to nonlinear disturbanres due to high- intensity hairpin eddies acoustically excited at the leading edge of boundary- layer plate. When disturbed by the leading-edge-generated hairpin eddies, the near wall flow is found to develop local wall shear layers with streamwise vortices. The local three- dimensional shear layers also evolve into hairpin eddies in succession to lead to the subcritical transition for displacement-thickness Reynolds numbers beyond 330. It is also shown that in terms of u- and v- fluctuations, the intensity of the near wall activity at the above-cited critical Reynolds number is almost the same (or slightly less than) that of the developed wall turbulence.
KeywordsReynolds Number Shear Layer Streamwise Vortex Wall Turbulence Wall Flow
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- 1.Nishioka, M. & Asai, M.: Evolution of Tollmien-Schlichting waves into wall turbulence. Turbulence and Chaotic Phenomena in Fluids (ed. T.Tatsumi ), North-Holland (1984) 87–92.Google Scholar
- 4.Gaster, M.: On the flow along swept leading edge. Aeronautical Quarterly 18 (1967) 165–184.Google Scholar
- 5.Poll, D.I.A.: Transition in the infinite swept attachment line boundary layer. Aeronautical Quarterly 30 (1979) 607–629.Google Scholar
- 6.Nishioka, M., Asai, M. & Iida, S.: Wall phenomena in the final stage of transition to turbulence. Transition and Turbulence (ed. R.E.Meyer), Academic Press (1981) 113–126.Google Scholar
- 7.Nishioka, M., Asai, M. & Iida, S.: An experimental investigation of the secondary instability. laminar- Turbulent Transition (eds. R.Eppler & H.Fasel), Springer-Verlag (1980)37–46.Google Scholar
- 8.Nishioka, M.: Laminar-turbulent transition in plane Poiseuille flow. Recent Studies on Turbulent Phenomena (eds. T.Tatsumi, H.Maruo & H.Takami ), Association for Science Documents Information (1985) 193–203.Google Scholar