Interaction of Bubbles with Vortex Ring Launched into Bubble Plume

Uchiyama, Tomomi; Kusamichi, Sou

doi:10.4236/aces.2013.34027

Cited by 13 publications

(28 citation statements)

References 25 publications

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“…There have also been studies of the interaction of vortex rings with a large number of microbubbles. These include the experimental study of Uchiyama & Kusamichi (2013), and the simulations of Ferrante & Elghobashi (2007). In the latter case, involving the interactions of a large number of microbubbles with a Taylor-Green vortex, Ferrante & Elghobashi (2007) observed that bubbles settle in the core of the vortex, reducing the vorticity and enstrophy.…”

Section: Literature Overviewmentioning

confidence: 99%

Interaction of a vortex ring with a single bubble: bubble and vorticity dynamics

Jha

Govardhan

2015

J. Fluid Mech.

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The interaction of a single bubble with a single vortex ring in water has been studied experimentally. Measurements of both the bubble dynamics and vorticity dynamics have been done to help understand the two-way coupled problem. The circulation strength of the vortex ring (Γ ) has been systematically varied, while keeping the bubble diameter (D b ) constant, with the bubble volume to vortex core volume ratio (V R ) also kept fixed at about 0.1. The other important parameter in the problem is a Weber number based on the vortex ring strength (We = 0.87ρ(Γ /2πa) 2 /(σ /D b ); a = vortex core radius, σ = surface tension), which is varied over a large range, We = 3-406. The interaction between the bubble and ring for each of the We cases broadly falls into four stages. Stage I is before capture of the bubble by the ring where the bubble is drawn into the low-pressure vortex core, while in stage II the bubble is stretched in the azimuthal direction within the ring and gradually broken up into a number of smaller bubbles. Following this, in stage III the bubble break-up is complete and the resulting smaller bubbles slowly move around the core, and finally in stage IV the bubbles escape. Apart from the effect of the ring on the bubble, the bubble is also shown to significantly affect the vortex ring, especially at low We (We ∼ 3). In these low-We cases, the convection speed drops significantly compared to the base case without a bubble, while the core appears to fragment with a resultant large decrease in enstrophy by about 50 %. In the higher-We cases (We > 100), there are some differences in convection speed and enstrophy, but the effects are relatively small. The most dramatic effects of the bubble on the ring are found for thicker core rings at low We (We ∼ 3) with the vortex ring almost stopping after interacting with the bubble, and the core fragmenting into two parts. The present idealized experiments exhibit many phenomena also seen in bubbly turbulent flows such as reduction in enstrophy, suppression of structures, enhancement of energy at small scales and reduction in energy at large scales. These similarities suggest that results from the present experiments can be helpful in better understanding interactions of bubbles with eddies in turbulent flows.

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Section: Literature Overviewmentioning

confidence: 99%

Interaction of a vortex ring with a single bubble: bubble and vorticity dynamics

Jha

Govardhan

2015

J. Fluid Mech.

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“…Small gas bubbles in a liquid flow preferentially distribute around the high-vorticity region [8,9]. By noting that the vorticity is highly concentrated on the vortex core of the vortex ring, one of the authors [10] conducted an experimental study on the behavior of a vortex ring in bubbly mixtures. Small hydrogen bubbles were generated by water electrolysis at the bottom of a water tank.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Entrainment and Transport of Gas Bubbles by a Vortex Ring

Uchiyama¹,

Yoshii²

2015

J Chem Eng Process Technol

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The control of the motion of small gas bubbles by a vortex ring is explored through numerical simulation. Hydrogen bubbles with a diameter of 0.2 mm are arranged in quiescent water, forming a bubble cluster. A vortex ring is launched vertically, passing through the bubble cluster. The behaviors of the vortex ring and bubble motion are analyzed. The diameter of the vortex ring at launch is 42.5 mm, and the bubble volume fraction is less than 0.04. As the vortex ring convects through the bubble cluster, it displaces and entrains the bubbles. After the vortex ring passes through the cluster, the bubbles are involved in the vortex ring. The research also clarifies the evolution of the diameter and circulation of the vortex ring.

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“…The present authors [1]- [3] have performed numerical and experimental investigations on the transport of bubbles in water. Uchiyama [1] conducted a numerical simulation of a water jet laden with small air bubbles and showed that a vortex ring, induced near the nozzle outlet by an axisymmetric disturbance, incorporates the bubbles and convects with them along the jet centerline.…”

Section: Introductionmentioning

confidence: 99%

“…Their simulation found that the bubbles are entrained and transported by the vortex ring and that the strength of the vortex ring is affected by the entrained bubbles. Uchiyama and Kusamichi [3] performed an experimental study to explore the interaction between a bubble cluster and a vortex ring. Small hydrogen bubbles were generated by water Manuscript received March 16, 2017; revised July 5, 2017.…”

Section: Introductionmentioning

confidence: 99%

Generation and Transport of Solid Particle Clusters Using a Vortex Ring Launched into Water

Uchiyama¹,

Yano²,

Degawa³

2017

IJCEA

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Abstract-A vortex ring launched into quiescent water is used to generate and transport solid particle clusters. A vortex ring launcher, comprising a cylinder and piston, is mounted at the bottom of a water tank. One-hundred spherical, polyacetal particles (mean diameter: 1.52 mm, density: 1417 kg/m 3 ) are placed on a mesh stretched near the cylinder outlet. The piston is used to discharge water in the cylinder vertically upward into the tank; this launches a particle-laden vortex ring. This solid-liquid two-phase flow is investigated at the Reynolds number Re, defined by the piston velocity and the cylinder diameter, of 6500, 7500, and 13000. When Re=6500, the particles are not entrained in the vortex ring, and therefore a cluster is not produced. Particles are entrained just after the launch of vortex rings at Re=7500 and 13000. These particle clusters are transported by the convection of the vortex ring. The velocity of water in the central vertical cross-section of the vortex ring decreases because of the particles, resulting in decreased circulation of the vortex ring. This reduction is more severe for lower Re.Index Terms-Solid-liquid, two-phase flow, vortex ring, particle entrainment, Piv.

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Interaction of Bubbles with Vortex Ring Launched into Bubble Plume

Cited by 13 publications

References 25 publications

Interaction of a vortex ring with a single bubble: bubble and vorticity dynamics

Interaction of a vortex ring with a single bubble: bubble and vorticity dynamics

Numerical Study of the Entrainment and Transport of Gas Bubbles by a Vortex Ring

Generation and Transport of Solid Particle Clusters Using a Vortex Ring Launched into Water

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