THE FORMATION AND STRUCTURE OF VORTEX RINGS

1964 ◽  
Vol 42 (4) ◽  
pp. 678-683 ◽  
Author(s):  
R. H. Magarvey ◽  
C. S. MacLatchy
Keyword(s):  
Thin Layer ◽  
Experimental Evidence ◽  
Vortex Ring ◽  
Flow Patterns ◽  
Vortex Rings ◽  
Qualitative Investigation ◽  
Ambient Fluid ◽  
Preliminary Examination ◽  
The Stability ◽  
Circular Axis

A preliminary examination was made of the formation and structure of the classical vortex ring. It is inferred from the experimental evidence that the configuration is not a true ring, but a layer of disperse fluid rolled about a circular axis. The stability of this pseudo-ring was found to be a result of the stability of its two rolled layers. The evidence suggests that a thin layer of fluid demarcated by two surfaces of discontinuity of opposite vorticity is relatively stable. A qualitative investigation was made of the flow patterns within the structure, but no attempt was made to relate velocities to ring geometry or to the physical characteristics of the ambient fluid.

Flow Patterns of a Circular Vortex Ring With Density Difference Under Gravity

1972 ◽  
Vol 39 (4) ◽  
pp. 869-872 ◽  
Author(s):  
C.-J. Chen ◽  
L.-M. Chang
Keyword(s):  
Vortex Ring ◽  
Flow Patterns ◽  
Density Difference ◽  
Ambient Fluid ◽  
Stability Curve ◽  
The Stability

The evolution of a circular vortex ring with a density 1.5 times of the ambient fluid under gravity was investigated. Three distinct patterns, namely, laminar, wavy, and turbulent, were observed. It is found that approximately as Nre > 2000, the vortex becomes turbulent, as Nre < 1500, laminar but to disintegrate into subrings. The stability curve was determined.

Passive scalar mixing in vortex rings

2007 ◽  
Vol 582 ◽  
pp. 449-461 ◽  
Author(s):  
RAJES SAU ◽  
KRISHNAN MAHESH
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Vortex Ring ◽  
Nozzle Exit ◽  
Passive Scalar ◽  
Rate Of Change ◽  
Vortex Rings ◽  
Ambient Fluid ◽  
Stroke Length ◽  
Formation Number

Direct numerical simulation is used to study the mixing of a passive scalar by a vortex ring issuing from a nozzle into stationary fluid. The ‘formation number’ (Gharibet al. J. Fluid Mech.vol. 360, 1998, p. 121), is found to be 3.6. Simulations are performed for a range of stroke ratios (ratio of stroke length to nozzle exit diameter) encompassing the formation number, and the effect of stroke ratio on entrainment and mixing is examined. When the stroke ratio is greater than the formation number, the resulting vortex ring with trailing column of fluid is shown to be less effective at mixing and entrainment. As the ring forms, ambient fluid is entrained radially into the ring from the region outside the nozzle exit. This entrainment stops once the ring forms, and is absent in the trailing column. The rate of change of scalar-containing fluid is found to depend linearly on stroke ratio until the formation number is reached, and falls below the linear curve for stroke ratios greater than the formation number. This behaviour is explained by considering the entrainment to be a combination of that due to the leading vortex ring and that due to the trailing column. For stroke ratios less than the formation number, the trailing column is absent, and the size of the vortex ring increases with stroke ratio, resulting in increased mixing. For stroke ratios above the formation number, the leading vortex ring remains the same, and the length of the trailing column increases with stroke ratio. The overall entrainment decreases as a result.

Optimal Vortex Ring Formation: A Study of Vortex Ring Formation in Starting and Pulsed Jets (Keynote)

2003 ◽  
Author(s):  
Morteza Gharib
Keyword(s):  
Vortex Ring ◽  
Basic Element ◽  
Ring Formation ◽  
Nozzle Diameter ◽  
Vortex Rings ◽  
Jet Flows ◽  
Ambient Fluid ◽  
Pulsed Jets ◽  
Vortex Ring Formation ◽  
Maximization Principle

Pulsatile jet flows are found in many industrially relevant fluid mechanical problems. A common feature of these flows is that they are fundamentally a series of fluid pulses. This aspect of pulsatile jets implies vortex rings are a basic element of the resulting flow. The significance of this observation is based in part on the tendency of vortex rings to entrain ambient fluid during their formation, but more so on the recent discovery of the phenomenon of vortex ring pinch off. This phenomenon was characterized for starting jets (individual pulses) showing that for pulses sufficiently long with respect to the nozzle diameter (i.e., sufficiently large L/D), the vortex ring stops forming and pinches off from the generating jet. This represents a maximization principle for vortex ring formation and suggests that any effects associated with vortex ring formation in pulsatile jets (e.g., enhanced entrainment), might be able to be optimized by properly selecting the L/D for each pulse.

scholarly journals XX. The potential of an anchor ring.-Part II

1893 ◽  
Vol 184 ◽  
pp. 1041-1106 ◽  
Keyword(s):  
Vortex Ring ◽  
Cross Section ◽  
Steady Motion ◽  
Vortex Rings ◽  
Laplace’S Equation ◽  
Single Vortex ◽  
Laplace's Equation ◽  
The Stability ◽  
Work Done

This paper is a continuation of that at pp. 43-95 suprd , on “The Potential of an Anchor Bing.” In that paper the potential of an anchor ring was found at all external points; in this/its value is determined at internal points. The annular form of rotating gravitating fluid was also discussed in that paper; here the stability of such a ring is considered. In addition, the potential of a ring whose cross-section is elliptic, being of interest in connection with Saturn, is obtained. The similarity of the methods employed, as well as of the analysis, has led me to give in this paper also a determination of the steady motion of a single vortex-ring in an infinite fluid, and of several fine vortex rings on the same axis. In Section I. solutions of Laplace’s equation applicable to space inside an anchor ring are obtained. These results are applied to obtain the potential of a solid ring at internal points, and also of a distribution of matter on the surface of the ring. The work done in collecting the ring from infinity is obtained.

X. On the vibrations of a vortex ring, and the action of two vortex rings upon each other

1882 ◽  
Vol 33 (216-219) ◽  
pp. 145-147 ◽  
Keyword(s):  
Angular Velocity ◽  
Vortex Ring ◽  
Cross Section ◽  
Vortex Core ◽  
Molecular Rotation ◽  
Vortex Rings ◽  
The Cross ◽  
Circular Axis

In the first part of the paper it is shown that if the circular axis of a vortex ring be displaced so as to be represented by the equations— ρ = a + α n cos nd , z = β u cos nd . when ρ is the distance of a point on the circular axis from the straight axis, and z the distance of a point on the circular axis from its mean plane, then— α n = A cos (ω e 2 /2 a 2 log 2 a / e n √ n 2 —1 . t + B), β n = A √ n 2 —1/ n sin ((ω e 2 /2 a 2 log 2 a / e n √ n 2 —1 . t + B), when ω is the angular velocity of molecular rotation, e the radius of the cross section of the vortex core, and a the radius of the aperture. The cross section is supposed small compared with the aperture so that e is small compared with a .

A balloon bursting underwater

2015 ◽  
Vol 769 ◽  
pp. 522-540 ◽  
Author(s):  
A. R. Vasel-Be-Hagh ◽  
R. Carriveau ◽  
D. S.-K. Ting
Keyword(s):  
Surface Tension ◽  
Vortex Ring ◽  
Buoyancy Force ◽  
Reasonable Agreement ◽  
Ring Expansion ◽  
Vortex Rings ◽  
Rise Velocity ◽  
Modified Model ◽  
The Stability ◽  
Buoyant Vortex Rings

A buoyant vortex ring produced by an underwater bursting balloon was studied experimentally. The effect of dimensionless surface tension on characteristics including rise velocity, rate of expansion, circulation, trajectory, and lifetime of the vortex ring bubble was investigated. Results showed reasonable agreement with the literature on vortex rings produced by conventional approaches. It was observed that as the dimensionless surface tension increased, the rise velocity, the circulation and consequently the stability of the vortex ring bubble increased; however, the rate of expansion tends toward constant values. A semi-analytical model is proposed by modifying the drag-based model presented by Sullivan et al. (J. Fluid Mech., vol. 609, 2008, pp. 319–347) to make it applicable to buoyant vortex rings. The modified model suggests that the vortex ring expansion is essentially due to the buoyancy force. An expression is also derived for the circulation in terms of the initial volume of the balloon and the depth at which the balloon bursts.

Latitudinal point vortex rings on the spheroid

2010 ◽  
Vol 466 (2118) ◽  
pp. 1749-1768 ◽  
Author(s):  
Sun-Chul Kim
Keyword(s):  
Vortex Ring ◽  
Stereographic Projection ◽  
Vortex Motion ◽  
Point Vortex ◽  
Vortex Rings ◽  
Dynamical Equations ◽  
Conformal Metric ◽  
The Stability ◽  
Pole Vortex

Point vortex motion on the surface of a spheroid is studied. Exact dynamical equations from the corresponding Hamiltonian are constructed by computing the conformal metric which induces a modified stereographic projection. As a concrete example, the motion of point vortices at the same latitude (called the point vortex ring ) is investigated as an extension of the sphere case. The role of eccentricity to the stability of the rotating motion is analysed. The influence of a pole vortex is also discussed.

The dynamics of vortex rings: Leapfrogging, choreographies and the stability problem

2013 ◽  
Vol 18 (1-2) ◽  
pp. 33-62 ◽  
Author(s):  
Alexey V. Borisov ◽  
Alexander A. Kilin ◽  
Ivan S. Mamaev
Keyword(s):  
Stability Problem ◽  
Vortex Rings ◽  
The Stability

Investigations Of Pressure Pulsations In A Model Of Draft Tube Of Hydraulic Turbine Caused By Vortex Rings

2016 ◽  
Vol 11 (4) ◽  
pp. 25-32
Author(s):  
Sergey Skripkin ◽  
Mikhail Tsoy ◽  
Sergey Shtork ◽  
Pavel Kuibin
Keyword(s):  
Vortex Ring ◽  
High Speed ◽  
Draft Tube ◽  
Hydraulic Turbine ◽  
Vortex Rings ◽  
Experimental Investigations ◽  
Visualization Technique ◽  
Vortex Rope ◽  
Hydro Turbine ◽  
Hydraulic Turbines

Current work is devoted to experimental investigations of behavior of precessing vortex rope in a draft tube model of hydraulic turbine. We used combination of stationary and freely rotating swirlers as a hydro turbine model. Such construction provides velocity distribution on the draft tube inlet close to distribution in natural hydraulic turbines operated at non-optimal conditions. The phenomenon of precessing vortex rope reconnection with further formation of vortex ring was founded in this experimental research using high-speed visualization technique. Synchronization of highspeed visualization and pressure measurements allowed us to relate pressure shock on the draft tube wall with vortex ring moving along wall.

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