Nonlinear Critical Layer in the Unsteady Boundary Layer Induced on a Flat Plate by Wakes

  • Z. Wierciński
Conference paper

Abstract

The paper reports results of experimental investigations of the wake — boundary layer interaction in the region of transition on a flat plate in a wind tunnel of low level of turbulence, Tu≤0.0008. Correlation analysis of velocity fluctuations across the induced boundary layer has revealed a region where a phase shift of external disturbances takes place. Spectral analysis of velocity fluctuations showed also strong attenuation of wakes harmonics in this region. The region exists for values of the Reynolds number Rex from 8.104to 2.105, is located at yc = 0.32 and has thickness dc = 0.22, which corresponds to the mean velocity (U/Uc)c equal to 0.74 in the boundary layer. The location of this region (higher than the highest possible critical layer location for the Tollmien-Schlichting waves) and the level of external disturbances e which is equal to 0.03 suggest that could be the nonlinear critical layer which has been analysed in the solution of the nonlinear Orr-Sommerfeld equation for the parameter λ=1/(Re* ε3/2) = O(1) (Benney&Bergeron, 1969, and Haberman, 1972).

Keywords

Boundary Layer Flat Plate Velocity Fluctuation External Disturbance Critical Layer 
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Copyright information

© Springer Science+Business Media Dordrecht 1998

Authors and Affiliations

  • Z. Wierciński
    • 1
  1. 1.Institute of Fluid-Flow Machinery PASci.GdańskPoland

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