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Step-induced separation of a turbulent boundary layer in incompressible flow

Published online by Cambridge University Press:  28 March 2006

P. Bradshaw
Affiliation:
Aerodynamics Division, National Physical Laboratory
P. V. Galea
Affiliation:
Aerodynamics Division, National Physical Laboratory

Abstract

Measurements of the low-speed flow up a step of height equal to 1·75 times the initial boundary-layer thickness show that the flow satisfies Stratford's (1959) condition for rapid separation, the extra stress gradients being confined to the first one-eighth of the boundary-layer thickness. The increase in turbulence intensity up to separation is small, and attributable to low-frequency fluctuations in separation position. Townsend's (1962) criterion predicts the separation point fairly accurately. A simple expression is found for the additional pressure rise that can be withstood by a boundary layer already fairly near separation, which gives tolerable results at any point in the flow up a step.

Type
Research Article
Copyright
© 1967 Cambridge University Press

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