On the wave damping due to a permeable seabed

Corvaro, Sara; Mancinelli, Alessandro; Brocchini, Maurizio; Seta, E.; Lorenzoni, Carlo

doi:10.1016/j.coastaleng.2010.06.005

Cited by 30 publications

(21 citation statements)

References 22 publications

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“…It points that the energy loss decreases as the increase of wavenumber in one wavelength range. The trend of theoretical solution agrees with the numerical and experimental results (Karunarathna and Lin, 2006;Corvaro, et al, 2010). …”

Section: The Influence Of Doppler Shift On the Energy Dissipationsupporting

confidence: 79%

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Energy Dissipation of Wave-Uniform Current Over a Rigid Porous Media With Finite Thickness

Lin

Hsu

Yu³

et al. 2014

Int. Conf. Coastal. Eng.

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The linear wave theory and the nonlinear-unsteady porous flow model are applied to analyze the energy dissipation and the bed pore water pressure induced by the interaction of wave, uniform current and porous bottom without considering the nonlinear waves and the viscosity effect inside the boundary layer. In this model, the linear, inertial and turbulent resistances are combined into a linearized resistance coefficient and the present system can be analyzed by a linear boundary value problem. The numerical result is quite agreement with the existing experimental data. It shows that the energy dissipation is reduced by the Doppler shift and the distribution of energy loss moves to the lower relative water depth region in the wave-following current. On the other hand, the bed pore water pressure in the wave-following current is always lager than that in the pure wave and the wave-opposing current.Keywords：wave-current interaction, rigid porous medium, nonlinear-unsteady porous flow model, energy dissipation 1.IntroductionThe Doppler shift is the relative motion which is the change in the frequency of waves for an observer moving relative to the source. In the water wave, it represents the wave-current interaction. Non-uniform or uniform currents influence the characteristics of waves. The speed and wavelength are increased in waves encountering a favorable current and vice verse for the opposing current (Nielsen, 2012).A lot of theoretical and experimental studies for wave-varying current interaction in the infinite and finite water depth with the smooth impermeable seabed had been performed. Typical samples are found in Stewart(1960,1961), Jonsson et al.(1970Jonsson et al.( ,1978, Jonsson(1977), Peregrine(1976), Thomas(1981Thomas( ,1990, Baddourand Song (1990), Groeneweg and Battjes (2003) (2013, 2014) used the perturbation approach to analyze the high-order nonlinear wave-current interaction in 3D Lagrangian scheme, and the mass transport velocity and the particle orbit both were measured in the 1D wave-current tank. In the laboratory experiment (Huang et al.,1972), it displayed the relative importance of wave-current interaction is decided by the nondimensional parameter 0 / U C with U as the current velocity and 0 C the wave speed without the current. The kinematics of the strong interaction in the wave-current motion were measured by Lai et al.(1989). Their results confirmed the critical 0 / U C with the currents induced the blockage of waves is -0.25. Soares and Pablo (2006) carried out an experimental study for the wave-current motion, and determined the change of wave spectra due to the coexistence of wave-current in the 3D wave basin. The experimental results showed that the energy absorbed by waves in the opposing current is impossible to continue the growth, and it is up to a certain limit, eventually resulting in wave breaking. However, the porous seabed and the energy dissipation are not considered in there existing studies.The experiment for the wave-current interaction over a rough bed was perfo...

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Section: The Influence Of Doppler Shift On the Energy Dissipationsupporting

confidence: 79%

“…A common nonlinear unsteady porous flow model can be shown in terms of pore pressure s p and discharge velocity V  as (Corvaro et al, 2010),…”

Section: Nonlinear-unsteady Porous Flow Modelmentioning

confidence: 99%

Energy Dissipation of Wave-Uniform Current Over a Rigid Porous Media With Finite Thickness

Lin

Hsu

Yu³

et al. 2014

Int. Conf. Coastal. Eng.

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“…Corvaro et al [2010] have pointed out the role that a variable C A can have in the near bed hydrodynamics. However, for simplicity a constant C A value is adopted here.…”

Section: Mathematical Formulationmentioning

confidence: 99%

On the role of infiltration and exfiltration in swash zone boundary layer dynamics

et al. 2015

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Boundary layer dynamics are investigated using a 2‐D numerical model that solves the Volume‐Averaged Reynolds‐Averaged Navier‐Stokes equations, with a VOF‐tracking scheme and a k ‐ ϵ turbulence closure. The model is validated with highly resolved data of dam break driven swash flows over gravel impermeable and permeable beds. The spatial gradients of the velocity, bed shear stress, and turbulence intensity terms are investigated with reference to bottom boundary layer (BL) dynamics. Numerical results show that the mean vorticity responds to flow divergence/convergence at the surface that result from accelerating/decelerating portions of the flow, bed shear stress, and sinking/injection of turbulence due to infiltration/exfiltration. Hence, the zero up‐crossing of the vorticity is employed as a proxy of the BL thickness inside the shallow swash zone flows. During the uprush phase, the BL develops almost instantaneously with bore arrival and fluctuates below the surface due to flow instabilities and related horizontal straining. In contrast, during the backwash phase, the BL grows quasi‐linearly with less influence of surface‐induced forces. However, the infiltration produces a reduction of the maximum excursion and duration of the swash event. These effects have important implications for the BL development. The numerical results suggest that the BL growth rate deviates rapidly from a quasi‐linear trend if the infiltration is dominant during the initial backwash phase and the flat plate boundary layer theory may no longer be applicable under these conditions.

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“…In Table 1 the wave characteristics over the physical model were summarized, where H i is the wave height at the upstream section of the physical model, h and L are, respectively, the water depth and the wave length over the physical model and Ur is the Ursell parameter expressed as Ur=H i L 2 /h 3 . The physical model is 1.5m long, although more significant damping would be achieved by using a longer porous bed (Corvaro et al 2010), the purpose of the present analysis is that of characterizing typical dynamics of nearshore waves evolving over dissipative seabeds. Breaking waves were not considered because the surface-generated turbulence could obscure too much the whole dynamics.…”

Section: Methodsmentioning

confidence: 99%

“…As the flow propagates through the porous medium, resistances act on the fluid due to both fluid viscosity and fluid-particle interactions. The wave height attenuation (Corvaro et al 2010) and the wave velocity reduction (Corvaro et al 2014a) were analyzed in previous works. Burcharth and Andersen (1995) and Van Gent (1995) discussed in detail the role of the different friction parameters which influence the flow through a porous medium.…”

Section: Introductionmentioning

confidence: 99%

Flow Dynamics of Waves Propagating Over Different Permeable Beds

Corvaro

Mancinelli

Brocchini

2017

Int. Conf. Coastal. Eng.

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The analysis of the hydrodynamics over porous media is of interest for many coastal engineering applications as the wave propagation over permeable structures or gravel beaches. The study of a boundary layer evolving over permeable beds is important to a better understanding of the interactions between the flow over and inside the porous medium. An experimental study has been performed to analyze the dynamics produced when waves propagate over two kinds of permeable beds: spheres (regular permeability) and natural stones. For comparative purposes the same analysis has been extended to two rough beds made, respectively, by a single layer of spheres and natural stones. We here focus on the correlation between the wave energy reduction induced by a porous bed and the flow resistance. An experimental law for the prediction of the friction factor is found by using the log-fit method in analogy to that reported in Dixen et al. (2008) for rough beds. Moreover, inspection of the turbulent velocity components allows one to evaluate the bottom shear stress. The latter analysis has been performed for different permeable beds (regular and irregular beds). A good agreement between the bottom shear stress behavior and the wave height attenuation over rough and permeable beds (Corvaro et al.

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On the wave damping due to a permeable seabed

Cited by 30 publications

References 22 publications

Energy Dissipation of Wave-Uniform Current Over a Rigid Porous Media With Finite Thickness

Energy Dissipation of Wave-Uniform Current Over a Rigid Porous Media With Finite Thickness

On the role of infiltration and exfiltration in swash zone boundary layer dynamics

Flow Dynamics of Waves Propagating Over Different Permeable Beds

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