Analysis of the flow in gravity currents propagating up a slope

Ottolenghi, Luisa; Adduce, Claudia; Roman, Federico; Armenio, Vincenzo

doi:10.1016/j.ocemod.2017.05.001

Cited by 41 publications

(10 citation statements)

References 41 publications

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“…The results obtained in sections 3.1 and 3.2 compare qualitatively with those obtained by Ottolenghi et al (2016aOttolenghi et al ( , 2016bOttolenghi et al ( , 2017a. A one-to-one comparison cannot be made on account of disparate definitions of Re used as well as the orientation of the slope.…”

Section: Effect Of Slope (θ) On Lar L-e Casessupporting

confidence: 52%

“…It has been accepted that mixing occurs at the interface through 2D K-H instabilities (Simpson 1972(Simpson , 1982. Recently, Ottolenghi et al (2017a), for L-E flows advancing up a slope, found strong turbulence in the neighborhood of K-H rolls which subsided with time while getting confined to the head region. This behavior is attributed to the K-H rolls losing their two-dimensional coherence to span-wise instabilities in the flow.…”

Section: Introductionmentioning

confidence: 99%

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Large-eddy-simulation approach in understanding flow structures of 2D turbulent density currents over sloping surfaces

2018

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A numerical investigation was performed to understand the flow dynamics of 2D density currents over sloping surfaces. Large eddy simulation was conducted for lock-exchange (L-E) release currents and overflows. 2D Navier-Stokes equations were solved using the Boussinesq approximation. The effects of the lock aspect-ratio (height/length of lock), slope, and Reynolds number on the flow structures and turbulence mixing have been analyzed. Results have confirmed buoyancy within the head of the two-dimensional currents is not conserved which contradicts the classical thermal theory. The lock aspect-ratio dictates the fraction of initial buoyancy which is carried by the head of the current at the beginning of the slumping (horizontal) and accelerating phase (over a slope), which has important implications on turbulence kinetic energy production, and hence mixing in the current. For L-E flows over a slope, increasing slope angle enhances the turbulence production. Increasing slope results in shear reversal within the density current resulting in shearinstabilities. Differences in turbulence production mechanisms and flow | The Japan Society of Fluid Mechanics Fluid Dynamics Research

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Section: Effect Of Slope (θ) On Lar L-e Casessupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Large-eddy-simulation approach in understanding flow structures of 2D turbulent density currents over sloping surfaces

2018

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“…Three-dimensional large eddy simulations (LES) of a fully turbulent lock-exchange gravity current were performed. LES simulations have been shown to accurately predict the behaviour of high Reynolds lock-exchange gravity currents at reasonable computational costs (Bonometti & Balachandar 2008; Ooi, Constantinescu & Weber 2009; Özgökmen, Iliescu & Fischer 2009; Tokyay, Constantinescu & Meiburg 2012, 2014; Meiburg, Radhakrishnan & Nasr-Azadani 2015; Ottolenghi et al 2016 b , 2017 a ; Kyrousi et al 2018; Pelmard et al 2018). A two-dimensional description of the turbulence statistics is generated by ensemble averaging 200 separate simulations and spanwise averaging (span averaging) of the domain.…”

Section: Introductionmentioning

confidence: 99%

Statistical characterisation of turbulence for an unsteady gravity current

2020

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“…Advanced numerical methods have been proposed to study planar gravity currents in complex geometries or bathymetries, e.g. Ooi, Constantinescu & Weber (2007, 2009, Gonzalez-Juez et al (2010), Tokyay, Constantinescu & Meiburg (2014), Dai (2015), Ottolenghi et al (2017aOttolenghi et al ( , 2018. The potential of using large eddy simulation (LES) and DNS in the simulation of Kelvin-Helmholtz and lobe and cleft instabilities in planar gravity currents at high Reynolds number has also been recently reviewed by Constantinescu (2014).…”

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confidence: 99%

Axisymmetric three-dimensional gravity currents generated by lock exchange

et al. 2018

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Unconfined three-dimensional gravity currents generated by lock exchange using a small dividing gate in a sufficiently large tank are investigated by means of large eddy simulations under the Boussinesq approximation, with Grashof numbers varying over five orders of magnitudes. The study shows that, after an initial transient, the flow can be separated into an axisymmetric expansion and a globally translating motion. In particular, the circular frontline spreads like a constant-flow-rate, axially symmetric gravity current about a virtual source translating along the symmetry axis. The flow is characterised by the presence of lobe and cleft instabilities and hydrodynamic shocks. Depending on the Grashof number, the shocks can either be isolated or produced continuously. In the latter case a typical ring structure is visible in the density and velocity fields. The analysis of the frontal spreading of the axisymmetric part of the current indicates the presence of three regimes, namely, a slumping phase, an inertial-buoyancy equilibrium regime and a viscous-buoyancy equilibrium regime. The viscous-buoyancy phase is in good agreement with the model of Huppert (J.

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Analysis of the flow in gravity currents propagating up a slope

Cited by 41 publications

References 41 publications

Large-eddy-simulation approach in understanding flow structures of 2D turbulent density currents over sloping surfaces

Large-eddy-simulation approach in understanding flow structures of 2D turbulent density currents over sloping surfaces

Statistical characterisation of turbulence for an unsteady gravity current

Axisymmetric three-dimensional gravity currents generated by lock exchange

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