scholarly journals Discussion: “Significance of the Vortex Breakdown Phenomenon” (Benjamin, T. B., 1965, ASME J. Basic Eng., 87, pp. 518–522)

1965 ◽  
Vol 87 (2) ◽  
pp. 522-523
Author(s):  
R. C. Chanaud
Keyword(s):  
Vortex Breakdown ◽  
Breakdown Phenomenon

The dynamics of confined vortices

1982 ◽  
Vol 382 (1783) ◽  
pp. 335-360 ◽  
Keyword(s):  
Vortex Core ◽  
Axial Velocity ◽  
Vortex Tube ◽  
Vortex Breakdown ◽  
Laser Doppler Anemometer ◽  
Present Evidence ◽  
Cylindrical Vortex ◽  
Breakdown Phenomenon ◽  
Similarities And Differences ◽  
Independent Parameters

Referring to flow-visualization and laser-Doppler anemometer measurements of swirl and axial velocity profiles, we discuss the physics of the flow in a cylindrical vortex tube as various independent parameters are varied. Three main classes of flow occur, depending upon the location of a vortex jump within the vortex tube. We present evidence to suggest a connection between vortex breakdown and the criticality and stability of the vortex core upon which it occurs and attempt to reconcile the various explanations that have been proposed for the breakdown phenomenon. Similarities and differences between the present experiments and those of previous investigators are also pointed out. Finally, as an Appendix, we present the results of a hydraulic analogue of our vortex experiment.

Velocity Measurements of Vortex Breakdown in an Enclosed Cylinder

2001 ◽  
Vol 123 (3) ◽  
pp. 604-611 ◽  
Author(s):  
Kazuyuki Fujimura ◽  
Hiroaki Yoshizawa ◽  
Reima Iwatsu ◽  
Hide S. Koyama ◽  
Jae Min Hyun
Keyword(s):  
Laser Doppler Velocimetry ◽  
Vortex Breakdown ◽  
Rotating Disk ◽  
Velocity Fields ◽  
Laser Doppler ◽  
Velocity Measurements ◽  
Experimental Apparatus ◽  
Breakdown Phenomenon ◽  
Component Velocity ◽  
Flow Visualizations

Experimental measurements were carried out of three-component velocity fields inside a cylindrical container. Flow was driven by the rotation of the top endwall disk. The purpose of the precision laser-Doppler velocimetry measurements was to describe the velocity characteristics pertinent to the vortex breakdown phenomenon. A turntable experimental apparatus was fabricated. Extensive laser-Doppler measurements, as well as flow visualizations, were made for the aspect ratio 1.50 and 2.50, and the Reynolds number ranges 0.99×103-2.20×103. The measured meridional velocities were found to be consistent with the prior visualization studies. The characteristic changes in swirling motions in the vicinity of vortex breakdown bubble are depicted. Detailed flow patterns near the rotating disk are constructed by using the experimental data.

Significance of the Vortex Breakdown Phenomenon

1965 ◽  
Vol 87 (2) ◽  
pp. 518-522 ◽  
Author(s):  
T. B. Benjamin
Keyword(s):  
Vortex Breakdown ◽  
Swirling Flows ◽  
Longitudinal Vortex ◽  
Vortex Flows ◽  
Breakdown Phenomenon ◽  
Physical Principles

The essential points in the author’s published theory of this phenomenon are summarized, and their implications with regard to longitudinal vortex flows in general are reviewed. The primary aim is to emphasize the physical principles which underlie the theory, and most of the mathematical details are passed over here. It is proposed that these principles serve to rationalize a wide variety of possible behavior in swirling flows.

scholarly journals Flow patterns of non-Newtonian nanofluid flow in cylindrical enclosure with rotating endwall: Effects of nanoparticles concentration

2021 ◽  
Vol 321 ◽  
pp. 01009
Author(s):  
Haroun Ragueb ◽  
Hanan Lamraoui ◽  
Nabil Himrane ◽  
Belkacem Manser ◽  
Kacem Mansouri
Keyword(s):  
Recirculation Zone ◽  
Vortex Breakdown ◽  
Numerical Study ◽  
Stagnation Zone ◽  
Mixing Process ◽  
Nanofluid Flow ◽  
Breakdown Phenomenon ◽  
Nanoparticles Concentration ◽  
Simulation Results ◽  
End Wall

In this paper, a numerical study on the flow structure of non-Newtonian nanofluid in cylindrical enclosure with rotating end wall. The considered nanofluid, MWCNT-water, exhibits a strong power-law shear-thinning behavior with the increase in nanoparticles loading. The main focus in this study is the effect of nanoparticles concentration on the vortex breakdown phenomenon. The simulation results showed that adding a small amount of nanoparticle eliminate the vortex breakdown which is considered as a positive in mixing process. However, the increase in nanoparticles concentration as well as the enclosure aspect ratio promotes the apparition of secondary recirculation zone and stagnation zone.

Control of Vortex Breakdown in a Torsionally Driven Closed Cylinder by Addition of Swirl Using a Small Disk

Volume 1 ◽  
2004 ◽  
Author(s):  
L. Mununga ◽  
M. C. Thompson ◽  
K. Hourigan ◽  
T. Leweke
Keyword(s):  
Experimental Approach ◽  
Vortex Breakdown ◽  
Cylindrical Vessel ◽  
Small Disk ◽  
Axis Of Rotation ◽  
Counter Rotation ◽  
Breakdown Phenomenon ◽  
Upstream Direction ◽  
Initial Results

This paper discusses results of a new experimental approach to control vortex breakdown in a confined cylindrical vessel with a rotating top endwall. The aim was to determine the effectiveness of adding co-rotating and counter rotating swirl near the axis of rotation using a small disk located in the bottom endwall. Initial results, with only the top end rotating, were satisfactorily validated against classical data from the literature. Results of the vortex breakdown onset, using this new non-intrusive approach, have revealed that co-rotation of the smaller disk precipitates vortex breakdown formation while counter rotation delays the onset of the breakdown phenomenon. It has also been shown that co-rotation increases the bubble radial and axial dimensions while shifting the bubble in the upstream direction. By contrast, counter rotation tends to reduce the size of the bubble, or completely suppress it, while shifting the bubble in the downstream direction.

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