Nonlinear regimes of tsunami waves generated by a granular collapse

Sarlin, Wladimir; Morize, Cyprien; Sauret, Alban; Gondret, Philippe

doi:10.1017/jfm.2021.400

Cited by 18 publications

(30 citation statements)

References 24 publications

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“…One obtains β ≈ 0.74 for the upper branch and β ≈ 0.45 for the lower one. It can be noted that the power law obtained for the upper branch is close to the values reported in the literature (see [24,26] and reference [23] which reports a power law η 0,max /H w = 1.23F r 0.8 max ), while the lower branch is more concave with lower values of wave amplitudes when F r max > 1. To the best of the authors' knowledge, this second branch has not been reported in the literature yet.…”

Section: Relevant Dimensionless Numbers Of Slide-to-wave Interactionsupporting

confidence: 86%

“…The dimensionless wave maximum amplitude is deduced from equations ( 24) and ( 25)-( 27), and shown in figure 12 along with numerical measurements. In the framework of the rectangular model, the actual dependency of the wave maximum amplitude with F r max is expected to lie in the blue shaded region (see figure 12) defined by equations (25) and (26) which can be considered as two end-members for the dependency of the celerity of perturbations with their own elevation. Recall that the model of rectangular collapse is expected to hold for slides which hardly deform, typically leading to solitary-like waves for F r max ≤ 0.58 (see figure 9).…”

Section: B Implications For Wave Predictionmentioning

confidence: 99%

“…Note that η(t) is maximum when F r(t) is maximum itself. Recently, Sarlin et al [26] showed that most of the wave types identified in their experiments of a granular column collapsing at the surface of a water tank, can be produced by the motion of a piston or wave-maker. For example, in the case of solitary-like waves, based on (2) and taking c = c max = √ gH w (1 + η 0,max /(2H w )), the authors showed that the maximum velocity of the slide front measured in their experiments was comparable to the expected maximum wavemaker velocity v p,max , having…”

Section: Introductionmentioning

confidence: 99%

“…This highlights the robustness of the η 0,max (F r max ) relationship. The relationships in [26] are a first attempt to build the full dynamical process from the collapsing dynamics towards the wave generation. Nevertheless, these relationships still require the knowledge of the sliding dynamics when v p is maximum.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of impulse waves generated by a viscous collapse in water

2022

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The generation of tsunamis by landslides has been the object of a lot of studies, focusing in particular on the wave maximum amplitude η0,max to quantitatively assess the damage which these events may cause. The literature has long identified that this amplitude η0,max is correlated to a Froude number F rmax proportional to a maximum slide front velocity ẋf,max . Yet, the dynamics of the slide needs to be determined from initial conditions to allow prediction of the maximum amplitude η0,max. Based on a canonical initial configuration, the aim of the present work is thus to better understand the transient physics connecting the landslide to the wave growth leading to the prediction of the wave maximum amplitude. In particular, the collapse of a Newtonian slide from air to water is considered here, investigating the role of two key ingredients: the slide inertia and viscous dissipation. The parameter space is systematically varied beyond laboratory and geophysical estimations to gain understanding on the fundamental process of wave formation, with 2D threephase numerical simulations using Basilisk. Results show that the column collapse of a Newtonian slide allows to capture most of the physics of wave formation, and the correlation between η0,max and the Froude number F rmax ∝ ẋf,max is recovered. A dynamical model of collapse reveals how the interplay between inertia and dissipation controls the slide dynamics through a Reynolds number Re(t) which, in turn, determines the kinematics of slide-water interface as quantified by the Froude number F r(t). A simple model based on an idealised evolution of the collapse dynamics and volume conservation allows to explicitly determine F rmax and η0,max from the initial condition. This model allows to capture results obtained from the numerical simulations and in accordance with empirical correlations usually found in the literature.

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Section: Relevant Dimensionless Numbers Of Slide-to-wave Interactionsupporting

confidence: 86%

Section: B Implications For Wave Predictionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling of impulse waves generated by a viscous collapse in water

2022

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“…However, it would be interesting to compare these results to the axisymmetric case, where different scalings govern the final morphology of the deposit [3]. Besides, such a configuration is more realistic for describing large geophysical flows such as landslides, which are a threat for human facilities both in mountainous and coastal areas, as landslides entering into water are known for their tsunamigenic potential [36][37][38][39][40].…”

Section: Discussionmentioning

confidence: 99%

Collapse dynamics of dry granular columns: from free-fall to quasi-static flow

Sarlin,

Morize,

Sauret

et al. 2021

Preprint

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Gravity-driven collapses involving large amounts of dense granular material, such as landslides, avalanches, or rockfalls, in a geophysical context, represent significant natural hazards. Understanding their complex dynamics is hence a key concern for risk assessment. In the present work, we report experiments on the collapse of quasi-two-dimensional dry granular columns under the effect of gravity, where both the velocity at which the grains are released and the aspect ratio of the column are varied to investigate the dynamics of the falling grains. At high release velocity, classical power laws for the final deposit are recovered, meaning those are representative of a free-fall like regime. For high enough aspect ratios, the top of the column undergoes an overall free-fall like motion. In addition, for all experiments, the falling grains also spread horizontally in a free-fall like motion, and the characteristic time of spreading is related to the horizontal extension reached by the deposit at all altitudes. At low release velocity, a quasi-static state is observed, with scaling laws for the final geometry identical to those of the viscous regime of granular-fluid flow. The velocity at which the grains are released governs the collapse dynamics. Between these two asymptotic regimes, the higher the release velocity, the smaller the impact on the collapse dynamics. The criterion V ≥ 0.4 √ gH0, where H0 is the initial height of the column, is found for the mean release velocity V not to influence the granular collapse.

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Numerical modeling of a potential landslide-generated tsunami in the southern Strait of Georgia

et al. 2023

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We report results of numerical simulations of a potential subaerial landslide on the coast of Orcas Island and the resultant tsunami waves in the southern Strait of Georgia near the US/Canada border. A likely trigger is strong ground shaking during large earthquakes on the nearby Holocene active Skipjack Island fault zone. For a worst-case scenario, we assume a 0.17 $${\textrm{km}}^3$$ km 3 rigid subaerial failure on the steep northeast coast of the island, spanning the $$\sim$$ ∼ 5 km between previous landslide deposits on the adjacent seafloor. The landslide motion and resulting tsunami generation are modeled using the three-dimensional (3D) non-hydrostatics physics-based NHWAVE model. The simulated failure moves downslope with a peak velocity of 13.64ṁ/s and travels 732 m before coming to rest after 85 s in 75-m water depth. Tsunami propagation is then continued using the 2D fully nonlinear and dispersive Boussinesq wave model FUNWAVE-TVD in a succession of layered and nested grids. The modeling reveals susceptible locations, particularly as waves will arrive with little or no warning. In the near-source region, modeled waves have peak amplitudes of 15–20 m, current speeds of up to 10 m/s, and runup of up to 30 m. Smaller, but significant, wave amplitudes and runup occur throughout the region surrounding Orcas Island. In the tsunami propagation direction, runup reaches 7.5 m at Neptune Beach near Lummi Bay. Both initial and reflected waves cause significant runup (> 1.5 m) along much of the shoreline between Point Roberts and Lummi Bay.

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Nonlinear regimes of tsunami waves generated by a granular collapse

Abstract: Abstract

Cited by 18 publications

References 24 publications

Modeling of impulse waves generated by a viscous collapse in water

Modeling of impulse waves generated by a viscous collapse in water

Collapse dynamics of dry granular columns: from free-fall to quasi-static flow

Numerical modeling of a potential landslide-generated tsunami in the southern Strait of Georgia

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