Particle Dispersion by Vortex Structures in Plane Mixing Layers

Kamalu, N.; Feng, Wei; Hanle, R.; Chung, J. N.; Crowe, C. T.

doi:10.1115/1.2910082

Cited by 112 publications

(51 citation statements)

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“…The vortical structures of the flow were often computed using point vortex methods, 13,14,39 a suitable approach for situations where large-scale vortices are clearly identified. It was established that dispersion of solid particles is mainly controlled by the Stokes number, which compares the particle relaxation time to the time scale of the flow.…”

Section: Bubble Dispersionmentioning

confidence: 99%

Dynamics of a two-dimensional upflowing mixing layer seeded with bubbles: Bubble dispersion and effect of two-way coupling

Climent

Magnaudet

2006

Physics of Fluids

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The evolution and structure of a spatially evolving two-dimensional mixing layer seeded with small bubbles are numerically investigated. The one-way coupling approach is first employed to show that characteristics of bubble dispersion are dominated by the possibility for sufficiently small bubbles to be captured in the core of the vortices. A stability analysis of the ordinary differential equation system governing bubble trajectories reveals that this entrapment process is governed by the presence of stable fixed points advected by the mean flow. Two-way coupling simulations are then carried out to study how the global features of a two-dimensional flow are affected by bubble-induced disturbances. The local interaction mechanism between the two phases is first analyzed using detailed simulations of a single bubbly vortex. The stability of the corresponding fixed point is found to be altered by the collective motion of bubbles. For trapped bubbles, the interphase momentum transfer yields periodic sequences of entrapment, local reduction of velocity gradients, and eventually escape of bubbles. Similar mechanisms are found to take place in the spatially evolving mixing layer. The presence of bubbles is also found to enhance the destabilization of the inlet velocity profile and to shorten the time required for the rollup phenomenon to occur. The most spectacular effects of small bubbles on the large-scale flow are a global tilting of the mixing layer centerline towards the low-velocity side and a strong increase of its spreading rate. In contrast, no significant modification of the flow is observed when the bubbles are not captured in the large-scale vortices, which occurs when the bubble characteristics are such that the drift parameter defined in the text exceeds a critical value. These two contrasted behaviors agree with available experimental results.

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Section: Bubble Dispersionmentioning

confidence: 99%

Dynamics of a two-dimensional upflowing mixing layer seeded with bubbles: Bubble dispersion and effect of two-way coupling

Climent

Magnaudet

2006

Physics of Fluids

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“…It should be noted that the terms used to define different mechanisms are our own and not referred to as such in the literature. In this context, it is interesting to mention the particle dispersion model of Wen et al 23 who suggest that the dispersion process involves two mechanisms operating in succession. The first one is a stretching mechanism whereby a vortex places the particles along the braid region, followed by the folding mechanism which distributes the particles along the periphery of the vortex during a pairing interaction.…”

Section: Discussionmentioning

confidence: 99%

Particle dispersion in a transitional axisymmetric jet - A numerical simulation

Uthuppan¹,

Aggarwal²,

Grinstein³

et al. 1994

AIAA Journal

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“…Particle motion is related to the behavior of large-scale eddies through the Stokes number St [8]. Studies of particle motion in a wake [9], in mixing layers [10], [11], and around a vortex pair [12] show that for St ≈ 1, particles accumulate in thin layers, outlining the boundaries of a large-scale eddy. Since Re = 13000 corresponds to St = 1.55 in the present experiment, the particles around the vortex core (Figs.…”

Section: A Behavior Of Vortex Ring Launched Without Solid Particlesmentioning

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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Particle Dispersion by Vortex Structures in Plane Mixing Layers

Cited by 112 publications

References 0 publications

Dynamics of a two-dimensional upflowing mixing layer seeded with bubbles: Bubble dispersion and effect of two-way coupling

Dynamics of a two-dimensional upflowing mixing layer seeded with bubbles: Bubble dispersion and effect of two-way coupling

Particle dispersion in a transitional axisymmetric jet - A numerical simulation

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

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