On the formation and propagation of nonlinear internal boluses across a shelf break

Venayagamoorthy, Subhas K.; Fringer, Oliver B.

doi:10.1017/s0022112007004624

Cited by 102 publications

(110 citation statements)

References 33 publications

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“…The 2D flow is characterized by a spatially growing stratified shear instability in the form of Kelvin-Helmholtz billows at the edge of the core, whereas three-dimensionalization of the flow is more relevant near the nose of the core where the lobe-cleft instability occurs. We shall mention that in the numerical experiments performed by Venayagamoorthy and Fringer (2007), the lobe-cleft instability is also observed but the shear instability is not present. In fact, our 3D simulation suggests that both of these instabilities develop and three-dimensionalize concurrently.…”

Section: The Vortex-rich Regionmentioning

confidence: 92%

“…The instability can eventually reach the pycnocline, modifying the wave breaking mechanism, though it is unclear to what extent three-dimensional effects will modify this observation. For periodically forced internal waves, three-dimensional simulations performed by Venayagamoorthy and Fringer (2007) suggest that interaction of shoaling waves with the bottom topography results in the formation of upslope-surging vortex cores of dense fluid, the so-called internal boluses, that propagate as gravity currents onto the shelf. Behaviour typical of gravity currents, such as the lobe-cleft instability, is observed in these boluses.…”

Section: Introductionmentioning

confidence: 99%

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Numerical simulations of shoaling internal solitary waves of elevation

Subich

Stastna

2016

Physics of Fluids

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We present high-resolution, two-and three-dimensional direct numerical simulations of laboratory-scale, fully nonlinear internal solitary waves of elevation shoaling onto and over a small-amplitude shelf. The three-dimensional, mapped coordinate, spectral collocation method used for the simulations allows for accurate modelling of both the shoaling waves and the bottom boundary layer. We focus on wave-induced instabilities during the shoaling and de-shoaling processes. The shoaling of the waves is characterized by the formation of a quasi-trapped core which undergoes a spatially growing stratified shear instability at its edge and a lobe-cleft instability in its nose. Both of these instabilities develop and three-dimensionalize concurrently, leading to strong bottom shear stress. During the deshoaling process, the core breaks up and ejects fluid that forms a vortex-rich region near the down-sloping portion of the shelf. The flow in this region is highly turbulent and the bottom shear stress is extremely strong. Experiments with a corrugated bottom boundary are also performed. Boundary layer separation is found inside each of the corrugations during the wave's shoaling process. Our analyses suggest that all of these wave-induced instabilities can lead to enhanced turbulence in the water column and increased shear stress on the bottom boundary. Through the generation and evolution of these instabilities, the shoaling and de-shoaling cycles of internal solitary waves of elevation are likely to provide systematic mechanisms for material mixing and sediment resuspension. These mechanisms have significant environmental implications on the near-coastal regions of the world's oceans.iii

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Section: The Vortex-rich Regionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Numerical simulations of shoaling internal solitary waves of elevation

Subich

Stastna

2016

Physics of Fluids

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“…We present details of the different stages of the interaction process that lead to wave breakdown and formation of internal boluses and their subsequent evolution toward smaller scales of motion and turbulence as they propagate onshore. In this article, we build on our previously published results (Venayagamoorthy and Fringer, 2007) from highly resolved three-dimensional numerical simulations of a vertical mode-1 internal wave interacting with a critical slope (i.e., the wave characteristic slope matches the topographic slope).…”

Section: Introductionmentioning

confidence: 99%

“…suggesting that the initial instability that occurs at the bolus front might be three dimensional (Simpson, 1972(Simpson, , 1997. Furthermore, through the use of gravity current scaling (Maxworthy et al, 2002), Venayagamoorthy and Fringer (2007) determined that these features propagate more like gravity currents than solitary waves.…”

Section: Introductionmentioning

confidence: 99%

Examining Breaking Internal Waves on a Shelf Slope Using Numerical Simulations

Venayagamoorthy¹,

Fringer²

2012

oceanog

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“…The EOF method was applied to the modal decomposition according to Venayagamoorthy and Fringer (2007), since the standard normal modes method is not suitable for the analysis of nonlinear and 25 nonhydrostatic forward-propagating long wave, amplitude-modulated wave packet and oscillating tail. Because of the shear effect on the mode-2 ISWs, the energy can cascade into all the modes, including mode-1 and higher modes.…”

Section: The Cascading Process Of Energymentioning

confidence: 99%

The evolution of mode-2 internal solitary waves modulated by background shear currents

Zhang¹,

Xu²,

Qun³

et al. 2018

Preprint

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Abstract. The evolution process of mode-2 internal solitary waves (ISWs) modulated by the background shear currents was investigated numerically. The forward-propagating long wave, amplitude-modulated wave packet were generated during the early stage of modulation, where the amplitude-modulated wave packet were suggested playing an important role in the energy transfer 15 process, and then the oscillating tail was generated and followed the solitary wave. Five different cases were introduced to assess the sensitivity of the energy transfer process to the Δ, which defined as a dimensionless distance between the centers of pycnocline and shear current. The forward-propagating long waves were found robust to the Δ, but the oscillating tail and amplitude-modulated wave packet decreased in amplitude with increasing Δ. The highest energy loss rate was observed when Δ = 0. In the 20 first 30 periods, ~36% of the total energy lost at an average rate of 9 W m -1 , it would deplete the energy of the solitary wave in ~4.5 h, corresponding to a propagation distance of ~5 km, which is consistent with the hypothesis of Shroyer et al. (2010), who speculated that the mode-2 ISWs are "short-lived" in the presence of shear currents.

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On the formation and propagation of nonlinear internal boluses across a shelf break

Cited by 102 publications

References 33 publications

Numerical simulations of shoaling internal solitary waves of elevation

Numerical simulations of shoaling internal solitary waves of elevation

Examining Breaking Internal Waves on a Shelf Slope Using Numerical Simulations

The evolution of mode-2 internal solitary waves modulated by background shear currents

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