On turbulent boundary-layer separation

Abstract

An experimental and analytical study of the separation of a turbulent boundary layer is reported. The turbulent boundary-layer separation model proposed by Sandborn & Kline (1961) is demonstrated to predict the experimental results. Two distinct turbulent separation regions, an intermittent and a steady separation, with correspondingly different velocity distributions are confirmed. The true zero wall shear stress turbulent separation point is determined by electronic means. The associated mean velocity profile is shown to belong to the same family of profiles as found for laminar separation. The velocity distribution at the point of reattachment of a turbulent boundary layer behind a step is also shown to belong to the laminar separation family.Prediction of the location of steady turbulent boundary-layer separation is made using the technique employed by Stratford (1959) for intermittent separation.

Kinematic and Acoustic Similarities of Separated Turbulent Boundary Layers

“…With the scaling introduced for the mean velocity profile in Eqs. (13) and (14), the Strouhal number is rewritten as where f + is a non-dimensional frequency and U 2 m is a non-dimensional time scale as a result of the proposed mixed scaling.…”

Turbulent Boundary-Layer Separation

“…Data (Simpson 1985) indicate that this closely describes the location of ITD. The mean wall ... , data of Sandborn & Liu (1968); *, data of Wadcock (1980); ... , data of So & Mellor (1972) (zero pressure gradient); T, data of Gersten et al (1983).…”

Break-away separation for high turbulence intensity and large Reynolds number

“…As Sandborn & Liu (1968) stated at the very beginning of their experimental study, 'Turbulent boundary-layer separation is normally listed as one of the most important unsolved problems in fluid mechanics . .…”