Pressure and Heat Flux Measurements on the Surface of a Low-Aspect-Ratio Circular Cylinder Mounted on a Ground Plate

Rödiger, Tim; Knauss, H.; Gaisbauer, U.; Krämer, Ewald

doi:10.1007/978-3-540-74460-3_15

Cited by 3 publications

(7 citation statements)

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“…The owl-face structure was not observed in situations with an oncoming thick boundary layer [6,13]. Near the rear end where the flow re-attaches on the cylinder top, a saddle point is formed on the centre line and this feature was correctly observed by Roh and Park [14] but also in oil-flow pictures [4,10]. The latter show in the front near the leading edge a further saddle point on the centre line where the reverse flow turns away (upwards) from the free-end wall and also turns outwards.…”

Section: Introductionmentioning

confidence: 57%

“…At the outset it must be said that due to the end effects the flow past a finiteheight cylinder is generally quite different from the vortex-shedding flow past long Oil flow visualization and Hölscher [6] 1993 surface pressure Richter and Leder [7] 2004 2.0 ≈0.0 20,30,50 LDA and surface Richter [8] 2005 pressure Hain et al [9] 2008 ≈2.0 ? 10 Tomographic and time resolved PIV in the free-end region Rödiger et al [10] 2007 2.0 0.092 20 Oil film visualization and surface pressure Sahin et al [11] 2007 -δ/D = 1.2 4 PIV-only in interaction region cylinder-ground plate Donnert et al [12] 2007 2.5 0. 1 4.4 Dye visualization and 5 2.2 tracer concentration measurements Fig.…”

Section: Introductionmentioning

confidence: 99%

“…In the majority of studies, the flow re-attaches on the free end, earlier when the cylinder is immersed in a boundary layer so that the freestream flow over the top carries turbulence [6,13]. Oil film studies [4,10] and detailed PIV measurements [9] show that the reverse flow in the front part of the free end develops an owl-face structure with focal points on the sides. These are the footprints of vortices that bend over laterally to form an arch vortex as shown in the sketch in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Large Eddy Simulations and Experiments of Flow Around Finite-Height Cylinders

Palau-Salvador

Stoesser

Fröhlich

et al. 2009

Flow Turbulence Combust

121

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The paper presents experimental and numerical results for the flow around a surface-mounted circular cylinder at the two height-to-diameter ratios of 2.5 and 5. The Reynolds number based on approach flow velocity and cylinder diameter is 43,000 and 22,000 for these two cases and the boundary layer of the approach flow has a thickness of about 10% of the cylinder height. The experiments comprise both flow visualizations with dye and laser Doppler velocimeter measurements of all mean velocity and fluctuation components. The numerical study is performed by an elaborate large eddy simulation on a staggered Cartesian grid using the immersed boundary method. The instantaneous flow behaviour including the shedding is analysed with information based on animations. For the long cylinder alternating shedding is found to occur over most of the height while for the shorter cylinder the shedding is observed mainly near the ground where it is also mostly alternating but intermittently also symmetrical. The mean-flow behaviour is analysed with the aid of streamlines and contour plots of mean-velocity and fluctuation components Flow Turbulence Combust (2010) 84:239-275 in various planes and a detailed comparison of LES and LDV results is provided, showing generally good agreement. The LES with very fine resolution near the free end allow a detailed study of the complex flow in this region with owl-face topology on the end wall previously observed in experiments. Behind the cylinder, the longitudinal recirculation region, the downstream development of tip vortices and the emergence of trailing vortices further downstream are analysed. The sum of the results, together with those from previous studies that were reviewed extensively, provides a comprehensive picture of the very complex flow behaviour.

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Section: Introductionmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Large Eddy Simulations and Experiments of Flow Around Finite-Height Cylinders

Palau-Salvador

Stoesser

Fröhlich

et al. 2009

Flow Turbulence Combust

121

View full text Add to dashboard Cite

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“…Surface pressure measurements performed upstream of the object showed a local minimum along the horseshoe vortex line and a local pressure maximum between the primary separation and horseshoe vortex lines. Similar upstream separation lines are formed with other surface-mounted geometries including a circular cylinder, pyramid, and cone [29][30][31] . Surface visualization downstream of wall-mounted objects typically displays two foci caused by the recirculation region behind the object 30 .…”

Section: Introductionmentioning

confidence: 70%

“…Similar upstream separation lines are formed with other surface-mounted geometries including a circular cylinder, pyramid, and cone [29][30][31] . Surface visualization downstream of wall-mounted objects typically displays two foci caused by the recirculation region behind the object 30 . Two vortices are generated at the foci positions and correspond to the "arch-type" or hairpin vortex seen in the wake of a wall-mounted hemispheroid 32 .…”

Section: Introductionmentioning

confidence: 70%

Investigating the Three-dimensional Flow Separation Induced by a Model Vocal Fold Polyp

Stewart

Erath

Plesniak

2014

JoVE

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The fluid-structure energy exchange process for normal speech has been studied extensively, but it is not well understood for pathological conditions. Polyps and nodules, which are geometric abnormalities that form on the medial surface of the vocal folds, can disrupt vocal fold dynamics and thus can have devastating consequences on a patient's ability to communicate. Our laboratory has reported particle image velocimetry (PIV) measurements, within an investigation of a model polyp located on the medial surface of an in vitro driven vocal fold model, which show that such a geometric abnormality considerably disrupts the glottal jet behavior. This flow field adjustment is a likely reason for the severe degradation of the vocal quality in patients with polyps. A more complete understanding of the formation and propagation of vortical structures from a geometric protuberance, such as a vocal fold polyp, and the resulting influence on the aerodynamic loadings that drive the vocal fold dynamics, is necessary for advancing the treatment of this pathological condition. The present investigation concerns the threedimensional flow separation induced by a wall-mounted prolate hemispheroid with a 2:1 aspect ratio in cross flow, i.e. a model vocal fold polyp, using an oil-film visualization technique. Unsteady, three-dimensional flow separation and its impact of the wall pressure loading are examined using skin friction line visualization and wall pressure measurements. Video LinkThe video component of this article can be found at

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