Journal ArticleDOI
The effect of short regions of high surface curvature on turbulent boundary layers
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In this article, the impulse response of the boundary layer, essentially the decay of structural changes downstream of concave or convex bends with turning angles of 20 or 30 degrees, was investigated.Abstract:
Measurements, including one-point double, triple or quadruple mean products of velocity fluctuations, have been made in low-speed turbulent, boundary layers on flat surfaces downstream of concave or convex bends with turning angles of 20 or 30 degrees, the length of the curved region being at most 6 times the boundary-layer thickness at entry These short bends approximate to ‘impulses’ of curvature, and the object of the work was to investigate the impulse response of the boundary layer, essentially the decay of structural changes downstream of the bends The work can be regarded as a sequel, with much more detailed measurements, to the study by So & Mellor (1972, 1973, 1975) who investigated the response to step increases of curvature: turbulent boundary layers being nonlinear systems, responses to several kinds of curvature history are needed to assemble an adequate description of the flow The most striking feature of the ‘impulse’ response is that the decay of the high turbulent intensity found at exit from the concave bends is not monotonic; the Reynolds stresses in the outer layer collapse to well below the level at entry, and are still falling slowly at the end of the test rig although in principle they must recover eventually On the convex (stabilized) side the flow recovers, monotonically in the main, from a low level of turbulent intensity at the exit The pronounced second-order response on the concave side can be explained qualitatively by interaction between the shear stress and the mean shear and is not peculiar to curved flows, but in the present cases the response is complicated by large changes in the dimensionless structure parameters related to double or triple mean products of velocity fluctuations Strong spanwise variations, due presumably to longitudinal vortices, further complicate the flow in the concave bends, and decay only very slowly downstreamread more
Citations
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Advances in CFD prediction of shock wave turbulent boundary layer interactions
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The Physics of Supersonic Turbulent Boundary Layers
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On the görtler instability of boundary layers
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Turbulence structure of a reattaching mixing layer
C. Chandrsuda,Peter Bradshaw +1 more
TL;DR: In this article, hot-wire measurements of second-and third-order mean products of velocity fluctuations have been made in the flow behind a backward-facing step with a thin, laminar boundary layer at the top of the step.
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Experimental study of three shock wave/turbulent boundary layer interactions
Alexander Smits,Kin Choong Muck +1 more
TL;DR: In this article, the authors present a systematic study of supersonic flow of a turbulent boundary layer over several compression-corner models and show that the shock wave/turbulent flow interaction did amplify the turbulent stresses dramatically, with amplification increasing with increasing turning angle.
References
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The Structure of Turbulent Shear Flow
TL;DR: In this paper, the authors present a method to find the optimal set of words for a given sentence in a sentence using the Bibliogr. Index Reference Record created on 2004-09-07, modified on 2016-08-08
Journal ArticleDOI
Calibration of the Preston tube and limitations on its use in pressure gradients
TL;DR: In this paper, it is shown that in sufficiently strong favorable and adverse pressure gradients the inner-law velocity distribution breaks down completely, and it is suggested that this breakdown is associated with reversion to laminar flow.
Journal ArticleDOI
Effects of spanwise rotation on the structure of two-dimensional fully developed turbulent channel flow.
TL;DR: In this article, experiments on fully developed turbulent flow in a channel which is rotating at a steady rate about a spanwise axis are described, and three stability related phenomena are observed or inferred: (1) the reduction (increase) of the rate of wall-layer streak bursting in locally stabilized (destabilized) wall layers; (2) the total suppression of transition to turbulence in a stabilized layer; (3) the development of large-scale roll cells on the destabilized side of the channel by growth of a Taylor-Gortler vortex instability.
Journal ArticleDOI
The reattachment and relaxation of a turbulent shear layer
Peter Bradshaw,F. Y. F. Wong +1 more
TL;DR: In this article, the authors show that the splitting of the shear layer at reattachment, where part of the flow is deflected upstream into the recirculating flow region to supply the entrainment, causes a pronounced decrease in eddy length scale, evidently because the larger eddies are torn in two.
Effects of Streamline Curvature on Turbulent Flow.
TL;DR: A review of current knowledge, a discussion of methods of predicting curvature effects, and a presentation of principles for the guidance of future workers can be found in this article, along with a progress report.