Landslide generated impulse waves were investigated in a two-dimensional physical laboratory model based on the generalized Froude similarity. The recorded wave profiles were extremely unsteady and nonlinear. Four wave types were determined: weakly nonlinear oscillatory wave, non-linear transition wave, solitary-like wave and dissipative transient bore. Most of the generated impulse waves were located in the intermediate water depth wave regime. Nevertheless the propagation velocity of the leading wave crest closely followed the theoretical approximations for a solitary wave. Between 4 and 50% of the kinetic slide impact energy propagated outward in the impulse wave train. The applicability ranges of the classical nonlinear wave theories to landslide generated impulse waves were determined. The main wave characteristics were related to the landslide parameters driving the entire wave generation process. The slide Froude number was identified as the dominant parameter. The physical model results were compared to the giant rockslide generated impulse wave which struck the shores of the Lituya Bay, Alaska, in 1958.

Near Field Characteristics of Landslide Generated Impulse Waves

An experimental study of a floating breakwater with asymmetric pneumatic chambers for wave energy extraction

Hydraulic performance and wave loadings of perforated/slotted coastal structures: A review

The present paper outlines the numerical calculation of wave interactions with a thin vertical slotted barrier extending from the water surface to some distance above the seabed, and describes laboratory tests undertaken to assess the numerical model. The numerical model is based on an eigenfunction expansion method and utilizes a boundary condition at the barrier surface that accounts for energy dissipation within the barrier. Numerical results compare well with previous predictions for the limiting cases of an impermeable barrier and a permeable barrier extending down to the seabed. Comparisons with experimental measurements of the transmission, reflection, and energy dissipation coefficients for a partially submerged slotted barrier show good agreement provided certain empirical coefficients of the model are suitably chosen, and indicate that the numerical method is able to account adequately for the energy dissipation by the barrier. The effects of porosity, relative wave length, wave steepness, and irregular waves are discussed and the choice of suitable parameters needed to model the permeability of the breakwater is described.

Wave Interactions with Vertical Slotted Barrier

[1] Tsunamis generated by deformable granular landslides are physically modeled in a three-dimensional tsunami wave basin based on the generalized Froude similarity. The dynamic landslide impact characteristics were controlled by means of a novel pneumatic landslide generator. The wave amplitudes, periods, and wavelengths are related to the landslide parameters at impact with the landslide Froude number being a dominant parameter. Between 1 and 15% of the landslide kinetic energy at impact is converted into the wave train energy. The wave amplitudes decay in radial and angular directions from the landslide axis. The first wave crest mostly travels with speeds close to the theoretical approximation of the solitary wave speed. The measured tsunami wave profiles were either of the nonlinear oscillatory or nonlinear transition type depending primarily on the landslide Froude number and relative slide thickness at impact. The generated waves range from shallow to deep water depth regimes, with the majority being in the intermediate water depth regime. Wave characteristics are compared with other two- and three-dimensional landslide tsunami studies and the results are discussed.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2011JC007850

Physical modeling of tsunamis generated by three-dimensional deformable granular landslides

The ratio between the flux of the energy taken out by the vortex generation process $e\_v$, and the incoming wave energy flux $e\_w$, is shown to be given by $e\_v/e\_w \approx 2\alpha \frac{2}{3}/{\mu[K^2\_1(\mu)+\pi^2I^2\_1(\mu)]}^\frac{4}{3},$ where $\alpha = \nu r\_0$ and $\mu = \nu T$ are non-dimensional parameters and $K\_1, I\_1$ are modified Bessel functions. The parameters $r\_0$ and $\nu$ are the amplitude and wavenumber of the incoming wave, respectively, and $T$ is the draught of the plate. This theoretically derived formula is in good agreement with experimental evidence.

Energy losses due to vortex shedding from the lower edge of a vertical plate attacked by surface waves

Solitary waves are generated in a wave tank by a piston-type wave generator. The measured surface profile, the wave celerity, and the near-bottom fluid particle velocity under the waves are compared to those given by the approximate solutions of Boussinesq, McCowan, and Laitone. It is found that, although Boussinesq's and McCowan's theories are of lower order of approximation than Laitone's theory, they better present the surface profile and the fluid particle velocity of the wave. The wave celerity, on the other hand, is not presented well by McCowan's theory. It is also found that the differences between the theories increase with increasing wave height to water depth ratio. Calculations of the fluid particle velocity near the bottom show that the three theories differ significantly when used to describe the fluid particle velocity square. It is recommended to generally use Boussinesq's theory as it represents the overall solitary wave better than the other two.

Ehud Naheer

Papers

Energy losses due to vortex shedding from the lower edge of a vertical plate attacked by surface waves

Laboratory Experiments with Solitary Wave

Scattering and dissipation of surface wave by a bi-plate structure*

On rubble-mound breakwaters of composite slope

Incipient motion of arbitrary shape particles under solitary waves