On the Boundary Layer Transition in Turbulent Flows with Various Length Scales

  • P. Jonáš
  • O. Mazur
  • V. Uruba
Conference paper
Part of the Fluid Mechanics and its Applications book series (FMIA, volume 36)

Abstract

Boundary layer transition is influenced by many factors, that cannot be described entirely and precisely in all particular cases. This fact is also the very reason for the scatter of various experimental results and computations published especially in connection with bypass-transition. Investigations of the bypass-transition consider mainly the effect of the intensity of the free-stream disturbances, almost neglecting the length scale of the disturbances. This is a little surprising in a view of the outstanding effect of an impermeable wall on the turbulent structure of the external flow (e.g. Thomas & Hancock [1977] and Hunt & Graham [1978]). Investigation of grid-turbulence passing a wall moving at the mean free-stream velocity documents the occurrence of two layers at the surface that results from the wall constraint of the flow and from the viscous sticking of the fluid to the surface. The first layer exhibits an outer kinematics region with the thickness about δs ~ 2Λe. The second layer governed by viscosity has the thickness \({{\delta }_{W}} \approx \sqrt {{6/R{{e}_{T}}}} \cdot {{\Lambda }_{e}} \). Here Λe and Re T are the turbulence length scale and the turbulence Reynolds number of the outer-flow. In both these layers significant changes of the turbulence structure occur. Usually during investigations of the by-pass transition, the outer-stream length scale exceeds the boundary layer thickness.

Keywords

Boundary Layer Boundary Layer Thickness Skin Friction Coefficient Boundary Layer Transition Turbulence Length Scale 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • P. Jonáš
    • 1
  • O. Mazur
    • 1
  • V. Uruba
    • 1
  1. 1.Institute of Thermomechanics AS CRPrague 8Czech Republic

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