Journal ArticleDOI
The flapping shear layer formed by flow separation from the forward corner of a square cylinder
D. A. Lyn,Wolfgang Rodi +1 more
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In this article, the phase-averaged velocities and turbulence intensities of the turbulent shear layer and the associated recirculation region on the sidewall formed in flow separation from the forward corner of a square cylinder have been studied with one-component laser-Doppler velocimetry.Abstract:
The turbulent shear layer and the associated recirculation region on the sidewall formed in flow separation from the forward corner of a square cylinder have been studied with one-component laser-Doppler velocimetry. Because of vortex shedding, the flow is approximately periodic, and is treated as a separated flow undergoing largeamplitude forcing at the shedding frequency. Phase (ensemble)-averaged velocities and turbulence intensities were obtained, and a close relationship in phase and amplitude between phase-averaged turbulence intensities and gradients of phase-averaged velocity is found in much of the flow region. The similarity behaviour of the phase-averaged profiles in the shear layer as well as the streamwise growth of the shear layer are investigated. While phase-averaged velocity profiles collapse well in similarity coordinates, normalized turbulence intensities exhibit systematic deviations from similarity. Shear-layer growth also departs markedly from the linear growth law of unforced plane mixing layers. The effect of the recirculation is suggested as a possible explanation for some of these deviations. Similarities to and differences from steady and forced mixing layers, steady separated flows with recirculation, and unsteady boundary layers are discussed.read more
Citations
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A laser-Doppler velocimetry study of ensemble-averaged characteristics of the turbulent near wake of a square cylinder
TL;DR: In this article, an ensemble-averaged statistics at constant phase of the turbulent near-wake flow (Reynolds number ≈ 21400 around a square cylinder) were obtained from two-component laser-Doppler measurements.
Journal ArticleDOI
Comparison of LES and RANS calculations of the flow around bluff bodies
TL;DR: In this article, the authors compared LES and RANS calculations of vortex sheddingding flow past a square cylinder at Re = 22.000 and of the 3D flow past the surface-mounted cube at Re < 40.000.
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Status of Large Eddy Simulation: Results of a Workshop
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Overview of turbulence models applied in CWE–1997
TL;DR: The state-of-the-art of utilizing turbulence models in wind engineering is reviewed in this article, where three types of numerical methods for analyzing turbulent flow (DNS, LES, RANS model) are presented.
Journal ArticleDOI
Filter-based unsteady RANS computations
TL;DR: Conditional averaging is adopted for the Navier–Stokes equation, and one more parameter, based on the filter size, is introduced into the k−e model, and the filter-based model is shown to improve the predictive capability considerably.
References
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Journal ArticleDOI
Coherent structures and turbulence.
TL;DR: In this article, a general scheme for educing coherent structures in any transitional or fully turbulent flow is presented, based on smoothed vorticity maps in convenient flow planes, which recognizes patterns of the same mode and parameter size, and then phase-aligns and ensembles them to obtain coherent structure measures.
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The mechanics of an organized wave in turbulent shear flow
TL;DR: In this paper, the amplitude and relative phase of the streamwise component of the induced wave is educed from a hot wire signal, allowing the wave speed and attenuation characteristics and the wave shape to be traced downstream.
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An experimental study of entrainment and transport in the turbulent near wake of a circular cylinder
Brian J. Cantwell,Donald Coles +1 more
TL;DR: In this paper, an experimental investigation of transport processes in the near wake of a circular cylinder at a Reynolds number of 140000 was performed using X-array hot-wire probes mounted on a pair of whirling arms, which increases the relative velocity component along the probe axis and decreases the relative flow angle to usable values in regions where fluctuations in flow velocity and direction are large.
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Strouhal numbers of rectangular cylinders
TL;DR: In this article, experiments on the vortex shedding frequencies of various rectangular cylinders were conducted in a wind tunnel and in a water tank and the results show how Strouhal number varies with a width-to-height ratio of the cylinders in the range of Reynolds number between 70 and 2 × l04.
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Subharmonics and vortex merging in mixing layers
Chih-Ming Ho,Lein-Saing Huang +1 more
TL;DR: In this paper, it was shown that the spreading rate of a mixing layer can be greatly manipulated at very low forcing level if the mixing layer is perturbed near a subharmonic of the most-amplified frequency.