An investigation of vorticity amplification in stagnation flow

Sadeh, Willy Z.; Sutera, Salvatore P.; Maeder, P.F.

doi:10.1007/bf01594830

Cited by 42 publications

(20 citation statements)

References 9 publications

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“…respectively. These tunnels have recently been described by Sadeh, Sutera & Maeder (1968) and Wood (1969). In the smaller of the two wind tunnels we studied a vortex street approaching the forward stagnation point of a 1·5 in.…”

Section: Experimental Apparatus and Instrumentationmentioning

confidence: 70%

On the phenomenon of vortex street breakdown

Durgin

Karlsson

1971

J. Fluid Mech.

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A von Karman vortex street generated in the usual way was subjected to a deceleration, thereby changing the ratio of longitudinal to lateral spacing between the vortices. Distortion of the individual vortices followed which resulted in annihilation of concentrated vortex regions and creation of a stationary wake flow. This wake flow was itself dynamically unstable and developed into a new vortex street of a different frequency from the initial one. The breakdown of the initial vortex street is qualitatively explained by considering the convection of a concentrated vortex region due to the motion imposed by all the other vortices.

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Section: Experimental Apparatus and Instrumentationmentioning

confidence: 70%

On the phenomenon of vortex street breakdown

Durgin

Karlsson

1971

J. Fluid Mech.

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“…Sutera et al [24] also identified a neutral scale which separated the small vortices dominated by dissipation from the larger vortices, whose energy is increased by the stretching mechanism. Sadeh et al [25] extended these calculations in the flow field outside the viscous layer and measured some turbulent properties in this region. They found a reasonable increase of the turbulence in the stagnation region, and this augmentation related to the structure of the impinging turbulence.…”

Section: Literature Surveymentioning

confidence: 98%

Investigation Into Methods of Enhancing Heat Transfer Under Impinging Air Jets

Can

2003

Experimental Heat Transfer

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Impinging air jets are widely used in industry, for heating, cooling, drying, etc., because of the high heat transfer rates which are developed in the impingement region. In this study, two methods of enhancing jet heat transfer have been investigated, namely, by using turbulence promoters to artificially raise the turbulence level, and by using a loudspeaker to excite the jet acoustically. In both these cases, the increases in heat transfer from enhancement were found to be modest. Some experimental hot-wire anemometry data obtained for free and impinging air jet flows are presented here. The existence of a relationship between turbulence intensity and heat transfer mechanism is also discussed.

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“…Within the ce I Is of this regular array of energy-containing eddies, the rotation alternates in its direction and turbulent energy accumulates. Most of the turhulence ampi iii rat iorr occurs at a most amplified scale A m [6] characteristic of the coherent substructure. This most amplified scale is generally greater than but commensurate with the thickness of the body boundary layer.…”

Section: Vorticity-ampeification Theorymentioning

confidence: 99%

“…An early review of this flow can be found in a report by Kestin and Maeder [2[. More recent theoretical analyses and experimental studies of turbulence amplification are presented in papers by Sutera, Maeder and Kestin 131, Sutera [4], Sadeh, Sutera and Maeder [5,6], Kestin and Wood [7], Bearman [8], Hunt [9], Traci and Wilcox []0], Sadeh and Brauer [1]], to mention a few.…”

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confidence: 99%

Turbulence Amplification in Flow About an Airfoil

Sadeh

Sullivan

1980

Volume 1B: General

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An experimental investigation of the evolution of freestream turbulence in flow about an airfoil was conducted in order to ascertain its selective amplification induced by the stretching mechanism according to the vorticity-amplification theory. Significant amplification of the streamwise turbulent energy transpired even in the limiting flow situation studied of a symmetric airfoil at zero angle of attack where the stretching is the least. Substantiation of the stretching effect was provided by the almost 100 percent amplification of turbulence with respect to its background level in the absence of the airfoil. Realization of preferred amplification at scales larger than the neutral scale of the stagnation flow was clearly indicated by the variation of the discrete streamwise turbulent energy. Particularly important was the detection of a most amplified scale which is characteristic of the coherent substructure near the airfoil stagnation zone and, concurrently, commensurate with the boundary-layer thickness.

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An investigation of vorticity amplification in stagnation flow

Cited by 42 publications

References 9 publications

On the phenomenon of vortex street breakdown

On the phenomenon of vortex street breakdown

Investigation Into Methods of Enhancing Heat Transfer Under Impinging Air Jets

Turbulence Amplification in Flow About an Airfoil

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