Asymmetric vortex merger: mechanism and criterion

Brandt, Laura; Cichocki, T. K.; Nomura, Keiko

doi:10.1007/s00162-009-0154-1

Cited by 10 publications

(4 citation statements)

References 12 publications

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“…6. The asymmetry effect during the destruction of elliptic eddy patches was found for the first time in (Kozlov and Makarov, 1984), where the authors also presented their considerations about inevitability of asymmetry at 3.3 < χ < 6.5; see also (Brandt et al, 2010). The thick solid lines show the corresponding boundaries for the elliptical lenses.…”

Section: B Evolution Of Elliptical Vorticesmentioning

confidence: 79%

Modeling the evolution of intrathermocline lenses in the Atlantic Ocean

Filyushkin¹,

Sokolovskiy²

2011

j mar res

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The existence of a tongue of Mediterranean Water (MW) at the depths of 500-1500 m is a characteristic feature of the hydrological regime in the northeastern part of the Atlantic Ocean. Anticyclonic eddies filled with MW (meddies or lenses) are observed in this region. They are identified via their high temperature and salinity anomalies, which compensate in density, yielding nearly homogeneous meddy cores. The analysis of historical observations has showed that approximately 100 lenses can exist simultaneously in this part of the ocean. High concentration of large water volumes (>4000 km 3 each) can be found both in the region of their origin near the Iberian Peninsula and near the Azores Frontal Zone. The latter is precisely the region in which merging of eddies can occur to form larger lenses. The existence of long-living lenses at large distances from the region of their formation is an indirect indication of the fact that merging of lenses occurs (MESOPOLYGON lens, SM1 lens in the SEMAPHORE experiment, and a lens in the Sargasso Sea). Here, we analyze the results of model experiments on interaction between two anticyclonic eddies applying the contour dynamics method (CDM) to a three-layer ocean. In these experiments, the vertical distribution of layerwise density in the layers, the horizontal size of the eddies (assumed to be cylindrical structures), and their depth location correspond to the observed conditions in the Atlantic Ocean. We show that the evolution of intrathermocline eddies and the evolution of barotropic eddies differ significantly. We found the behavior of interacting eddies in the middle layer depends on the Froude number. We determined the critical distances between the lenses when their merger begins and the destruction' criterion for the elliptical intrathermocline eddies.

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Section: B Evolution Of Elliptical Vorticesmentioning

confidence: 79%

Modeling the evolution of intrathermocline lenses in the Atlantic Ocean

Filyushkin¹,

Sokolovskiy²

2011

j mar res

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“…Lamb-Oseen vortex models closely mimic coherent vortex structures in two-dimensional turbulent flows [9]. One of the major phenomenon involved with Lamb-Oseen vortices is the merger of vortex cores [10][11][12].…”

Section: Introductionmentioning

confidence: 86%

Effect of external pulsation on kinematics of fluid particles in the field of Lamb–Oseen vortex pair

2017

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The effect of external pulsation on a pair of stationary Lamb-Oseen vortices of equal strength has been analyzed to investigate kinematic behavior of a fluid particle. The assumption of vortices being treated stationary or fixed vortex filaments is valid in a reference frame attached to the vortex system with axes along and perpendicular to the line of their centers. Also, it is assumed that change in core shape and size is much small, with least possibility of core merger. In such situations, periodic particle paths are observed and superposition of pulsation becomes beneficial. In the present work, motion of a representative fluid particle is modeled as a non-linear dynamical system by varying both amplitude and frequency of external pulsation. Effect of external pulsation has been brought out with the help of quantification of deviation from periodic paths by using the concept of total average deviation. Results are presented in terms of particle paths, velocity phase plots, velocity signals and their spectra for varying amplitude and frequency of external pulsation.

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“…To predict the occurrence of asymmetric vortex merging, a mutuality parameter, which involves the ratio between the strain rate and the vorticity of each vortex, can be used to determine the critical values at which vortex merging will occur. 78,79 However, this is not the focus of the current study.…”

Section: (Multimedia Views)]mentioning

confidence: 96%

Periodic fluctuations of streamwise vortices in inertia-dominated intersecting flows

et al. 2021

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In the proximity of stagnation points, flow instabilities tend to arise at relatively low Reynolds numbers (Re). These instabilities often manifest as vortices that can evolve time-periodic patterns as Re is increased. These types of flows are well studied in cases for which the stagnation point is fixed on an obstacle and the resulting vortices are in the spanwise direction (e.g., the von Kármán vortex street). However, they are less understood in intersecting flows, where the stagnation point is not wall-attached and the resulting vortices are stretched by the flow in the streamwise direction. In this study, quantitative flow velocimetry measurements and three-dimensional numerical simulations are used to characterize two types of steady vortical flow fields in rectangular, intersecting microfluidic geometries with different aspect ratios, α, of the intersecting channels. We show that by changing α, it is possible to precisely tune the features of the steady-state vortical flow field, including the number of vortices, their relative rotation direction, nearby circulation areas, and even vortex core structure. The unique steady-state features determine the onset parameters, dynamics, and frequency of time-periodic fluctuations that develop at higher Re. Our results can be directly applied for enhancing the control over the vortical motion of transported fluids in inertial microfluidics and lab-on-a-chip devices. Additionally, these findings contribute to the fundamental knowledge on vortical motion with the potential to improve the control over vortex-induced vibrations on obstacles in both terrestrial and marine environments.

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Asymmetric vortex merger: mechanism and criterion

Cited by 10 publications

References 12 publications

Modeling the evolution of intrathermocline lenses in the Atlantic Ocean

Modeling the evolution of intrathermocline lenses in the Atlantic Ocean

Effect of external pulsation on kinematics of fluid particles in the field of Lamb–Oseen vortex pair

Periodic fluctuations of streamwise vortices in inertia-dominated intersecting flows

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