Turbulent vortex dipoles in a shallow water layer

Sous, Damien; Bonneton, Natalie; Sommeria, Joël

doi:10.1063/1.1762912

Cited by 46 publications

(47 citation statements)

References 19 publications

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“…For example, in the region of strong downward motion the vertical velocity turns out to be of the order 25% of the horizontal velocity. At the front of the dipole one observes a feature referred to by Sous et al 28,29 as "frontal circulation," i.e., a roll-like flow structure with an upward motion in front of the dipole and a weaker downward motion in front of that ͓see Figs. 5͑b͒ and 5͑c͔͒.…”

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confidence: 99%

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The three-dimensional structure of an electromagnetically generated dipolar vortex in a shallow fluid layer

et al. 2008

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. (2008). The three-dimensional structure of an electromagnetically generated dipolar vortex in a shallow fluid layer. Physics of Fluids, 20(11), 116601-1/15. [116601]. DOI: 10.1063/1.3005452 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The three-dimensional structure of an electromagnetically generated dipolar vortex in a shallow fluid layer Many experiments have been performed in electromagnetically driven shallow fluid layers to study quasi-two-dimensional ͑Q2D͒ turbulence, the shallowness of the layer commonly is assumed to ensure Q2D dynamics. In this paper, however, we demonstrate that shallow fluid flows exhibit complex three-dimensional ͑3D͒ structures. For this purpose we study one of the elementary vortex structures in Q2D turbulence, the dipolar vortex, in a shallow fluid layer. The flow evolution is studied both experimentally and by numerical simulations. Experimentally, stereoscopic particle image velocimetry is used to measure instantaneously all three components of the velocity field in a horizontal plane, and 3D numerical simulations provide the full 3D velocity and vorticity fields over the entire flow domain. It is found that significant and complex 3D structures and vertical motions occur throughout the flow evolution, i.e., during and after the forcing phase. We conclude that the bottom friction is not the main mechanism leading to three-dimensionality of the flow but rather the impermeability of the boundaries. It is further shown that free-surface deformations, i.e., gravity waves, are of minor importance too as a mechanism to generate 3D motion. Furthermore, it is demonstrated that the observations are not due to three-dimensionality introduced by the forcing mechanism but intrinsically due to the flow dynamics itself. The flow evolution is analyzed with respect to its quasi-two-dimensionality by adopting the ratio of "horizontal" to "vertical" kinetic energies, the normalized horizontal divergence, and a measure of the relaxation to a Poiseuille-like profile. An important observation is that, although the relative magnitude of the vertical velocity as compared to the horizontal flow components decreases for decreasing fluid depth, the vertical profile of the horizontal flow relaxes rather slowly to a Poiseuille-like profile, i.e., not faster than the b...

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confidence: 99%

“…5͑b͒ and 5͑c͔͒. Note that Lin et al 22 ͑who were, to our knowledge, the first to report on this feature͒ and Sous et al 28,29 did not use the electromagnetic forcing method, but their dipoles were created by injecting a small amount of fluid horizontally in the tank.…”

Section: -5mentioning

confidence: 99%

The three-dimensional structure of an electromagnetically generated dipolar vortex in a shallow fluid layer

et al. 2008

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“…[62,63]). Lin et al [64] provide one of the more detailed descriptions of flow inside shallow TCS using small-scale experimental techniques.…”

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confidence: 99%

Tsunami currents in ports

Borrero

Lynett

Kalligeris

2015

Phil. Trans. R. Soc. A.

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Tsunami-induced currents present an obvious hazard to maritime activities and ports in particular. The historical record is replete with accounts from ship captains and harbour masters describing their fateful encounters with currents and surges caused by these destructive waves. Despite the well-known hazard, only since the trans-oceanic tsunamis of the early twenty-first century (2004, 2010 and 2011) have coastal and port engineering practitioners begun to develop port-specific warning and response products that accurately assess the effects of tsunami-induced currents in addition to overland flooding and inundation. The hazard from strong currents induced by far-field tsunami remains an underappreciated risk in the port and maritime community. In this paper, we will discuss the history of tsunami current observations in ports, look into the current state of the art in port tsunami hazard assessment and discuss future research trends.

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“…[17][18][19][20][21] In a frame co-moving with the dipole, the horizontal flow in a Lamb-Chaplygin dipole is described by the following stream function given in cylindrical coordinates (r, θ ): 22…”

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confidence: 99%

Strain-vorticity induced secondary motion in shallow flows

Kamp

2012

Physics of Fluids

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Deviations from two-dimensionality of a shallow flow that is dominated by bottom friction are quantified in terms of the spatial distribution of strain and vorticity as described by the Okubo-Weiss function. This result is based on a Poisson equation for the pressure in a quasi-horizontal (primary) flow. It is shown that the Okubo-Weiss function specifies vertical pressure gradients, which for their part drive vertical (secondary) motion. An asymptotic expansion of these gradients based on the smallness of the vertical to horizontal scale ratio demonstrates that the sign and magnitude of secondary circulation inside the fluid layer is dictated by the signs and magnitude of the Okubo-Weiss function. As a consequence of this, secondary motion as well as nonzero horizontal divergence do also depend on the strength, i.e., the Reynolds number of the primary flow. The theory is exemplified by two generic vortical structures (monopolar and dipolar structures). Most importantly, the theory can be applied to more complicated turbulent shallow flows in order to assess the degree of two-dimensionality using measurements of the free-surface flow only.

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Turbulent vortex dipoles in a shallow water layer

Cited by 46 publications

References 19 publications

The three-dimensional structure of an electromagnetically generated dipolar vortex in a shallow fluid layer

The three-dimensional structure of an electromagnetically generated dipolar vortex in a shallow fluid layer

Tsunami currents in ports

Strain-vorticity induced secondary motion in shallow flows

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