A merging criterion for two-dimensional co-rotating vortices

Meunier, Patrice; Ehrenstein, Uwe; Leweke, Thomas; Rossi, Maurice

doi:10.1063/1.1489683

Cited by 119 publications

(143 citation statements)

References 26 publications

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“…10 However, it is not evident whether this asymmetry appears in complicated vortical flows, since analysis and numerical verification were performed only for an idealized case of a co-rotating point vortex pair. In fluid dynamics, the merging of co-rotating vortices is one of the fundamental subjects, [11][12][13] and sound wave radiation from this configuration has been studied. 14 However, cyclone-anticyclone asymmetry in either gravity or sound waves has been reported so far.…”

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confidence: 99%

Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

Sugimoto

2015

Physics of Fluids

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Inertia-gravity wave radiation from the merging of two co-rotating vortices is investigated numerically in a rotating shallow water system in order to focus on cyclone–anticyclone asymmetry at different values of the Rossby number (Ro). A numerical study is conducted on a model using a spectral method in an unbounded domain to estimate the gravity wave flux with high accuracy. Continuous gravity wave radiation is observed in three stages of vortical flows: co-rotating of the vortices, merging of the vortices, and unsteady motion of the merged vortex. A cyclone–anticyclone asymmetry appears at all stages at smaller Ro (≤20). Gravity waves from anticyclones are always larger than those from cyclones and have a local maximum at smaller Ro (∼2) compared with that for an idealized case of a co-rotating vortex pair with a constant rotation rate. The source originating in the Coriolis acceleration has a key role in cyclone–anticyclone asymmetry in gravity waves. An additional important factor is that at later stages, the merged axisymmetric anticyclone rotates faster than the elliptical cyclone due to the effect of the Rossby deformation radius, since a rotation rate higher than the inertial cutoff frequency is required to radiate gravity waves.

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confidence: 99%

Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

Sugimoto

2015

Physics of Fluids

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“…The determination of (a/b) cr has been the focus of a number of studies, e.g., [11,10,9]. The physical mechanisms of symmetric merger have also been considered, e.g., [7,8,4,13,1,2].…”

Section: Introductionmentioning

confidence: 99%

“…Flow regime maps have been presented in terms of the initial core size (or strength) ratio and initial separation distance. Trieling et al [12] attempted to normalize the separation distance by an averaged core size, defined in terms of the second moment of vorticity [9]. However, this did not yield a universal critical aspect ratio delimiting the merging regimes.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric vortex merger: mechanism and criterion

Brandt¹,

Cichocki²,

Nomura³

2009

Iutam Bookseries

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The merging of two unequal co-rotating vortices in a viscous fluid is investigated. Two-dimensional numerical simulations of initially equal sized Lamb-Oseen vortices with differing relative strengths are performed. Results show how the disparity in deformation rates between the vortices alters the interaction. Key physical mechanisms associated with vortex merging are identified. A merging criterion is formulated in terms of the relative timing of core detrainment and destruction. A critical strain parameter is defined to characterize the establishment of core detrainment. This parameter is shown to be directly related to the critical aspect ratio in the case of symmetric merger.

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“…When two like-signed vortices come in close contact, they can merge to form a vortex which is often larger. Vortex merger has been studied in two-dimensional or quasi-geostrophic models, relevant to the mesoscale dynamics in the ocean interior (Overman and Zabusky, 1982;Dritschel, 1985Dritschel, , 1986Griffiths and Hopfinger, 1987: Melander et al, 1987, 1988Pavia and Cushman-Roisin, 1990;Carnevale et al 1991;Carton, 1992;Bertrand and Carton, 1993;Valcke and Verron, 1993;Verron and Valcke, 1994;Yasuda, 1995;Yasuda and Flierl, 1995;Verron, 1996, 1997;Yasuda and Flierl, 1997;von Hardenberg et al, 2000;Dritschel, 2002;Reinaud and Dritschel, 2002;Meunier et al, 2002;Bambrey et al 2007;Ozugurlu et al, 2008). Depending on the initial conditions, the merging process can finally form one large vortex or two asymmetric vortices.…”

Section: Introductionmentioning

confidence: 99%

Vortex merger in surface quasi-geostrophy

Carton

Ciani

Verron

et al. 2015

Geophysical & Astrophysical Fluid Dynamics

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The merger of two identical surface temperature vortices is studied in the surface quasigeostrophic model. The motivation for this study is the observation of the merger of submesoscale vortices in the ocean. Firstly, the interaction between two point vortices, in the absence or in the presence of an external deformation field, is investigated. The rotation rate of the vortices, their stationary positions and the stability of these positions are determined. Then, a numerical model provides the steady states of two finite-area, constant-temperature, vortices. Such states are less deformed than their counterparts in two-dimensional incompressible flows. Finally, numerical simulations of the nonlinear surface quasi-geostrophic equations are used to investigate the finite-time evolution of initially identical and symmetric, constant temperature vortices. The critical merger distance is obtained and the deformation of the vortices before or after merger is determined. The addition of external deformation is shown to favor or to oppose merger depending on the orientation of the vortex pair with respect to the strain axes. An explanation for this observation is proposed. Conclusions are drawn towards an application of this study to oceanic vortices.2

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A merging criterion for two-dimensional co-rotating vortices

Cited by 119 publications

References 26 publications

Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

Asymmetric vortex merger: mechanism and criterion

Vortex merger in surface quasi-geostrophy

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