http://personalpages.to.infn.it/~onorato/papers/2007_Cavaleri_etal_PO.pdf

Wave Modelling - The State of the Art

Numerical modelling to estimate the spatial distribution of the wave energy in the Portuguese nearshore

The WRT method for the computation of non-linear four-wave interactions in discrete spectral wave models

Evaluation of the wave conditions in Madeira Archipelago with spectral models

Extensive numerical simulations of fetch-limited growth of wind-driven waves are analysed within two approaches: a 'traditional' wind-speed scaling first proposed by Kitaigorodskii (Bull. Acad. Sci. USSR, Geophys. Ser., Engl. Transl., vol. N1, 1962, p. 105) in the early 1960s and an alternative weakly turbulent scaling developed recently by Badulin et al. (J. Fluid Mech. 591, 2007, 339―378). The latter one uses spectral fluxes of wave energy, momentum and action as physical scales of the problem and allows for advanced qualitative and quantitative analysis of wind-wave growth and features of air―sea interaction. In contrast, the traditional approach is shown to be descriptive rather than proactive. Numerical simulations are conducted on the basis of the Hasselmann kinetic equation for deep-water waves in a wide range of wind speeds from 5 to 30 m s ―1 and for the ideal case of fetch-limited growth: permanent wind blowing perpendicularly to a straight coastline. Two different wave input functions, S in , and two methods for calculating the nonlinear transfer term S nl (Gaussian quadrature method, or GQM, a quasi-exact method based on the use of Gaussian quadratures, and the discrete interaction approximation, or DIA) are used in the simulations. Comparison of the corresponding results firstly shows the relevance of the analysis of wind-wave growth in terms of the proposed weakly turbulent scaling, and secondly, allows us to highlight some critical points in the modelling of wind-generated waves. Three stages of wind-wave development corresponding to qualitatively different balance of the source terms, S in , S diss and S nl , are identified: initial growth, growing sea and fully developed sea. Validity of the asymptotic weakly turbulent approach for the stage of growing wind sea is determined by the dominance of nonlinear transfers, which results in a rigid link between spectral fluxes and wave energy. This stage of self-similar growth is investigated in detail and presented as a consequence of three sub-stages of qualitatively different coupling of air flow and growing wind waves. The key self-similarity parameter of the asymptotic theory is estimated to be α ss = 0.68 ± 0.1. Further prospects of wind-wave modelling in the context of the presented weakly turbulent scaling are discussed.

On weakly turbulent scaling of wind sea in simulations of fetch-limited growth

A new computational scheme for calculating the nonlinear energy transfer in finite-depth gravity wave spectra has been developed by extending the methods established by Masuda (1980) and Komatsu et...

Numerical computations of the nonlinear energy transfer of gravity-wave spectra in finite water depths

A tsunami caused by the Hokkaido-Nansei-oki earthquake struck Okushiri Island and the southwest coast of Hokkaido damaging many port facilities. This paper describes typical breakwater damage at Okushiri Port and the applicability of Tanimoto's formula for tsunami wave forces on vertical walls based on prototype failure analyses and the result of numerical simulations. The armor stability and the rubble mound scourings were examined from the results of 3-D model tests at a scale of 1/15. The damage patterns at the narrow opening of breakwaters were reproduced by the tests. The necessary weight of armor blocks and foot-protection blocks for breakwater heads were calculated by the C.E.R.C. formula using averaged flow speed at the peak of tsunami.

/pdf/breakwater-damage-in-okushiri-port-due-to-the-hokkaido-1cxte6nzzl.pdf

Breakwater Damage in Okushiri Port Due to the Hokkaido Nansei-Oki Earthquake Tsunami

To investigate the effects of currents on estimations of directional wave spectra, the problems with the existing methods for obtaining directional wave spectra are discussed when they are applied to wave fields in the existence of currents. The characteristics of distortion of the estimated spectra by current effects are examined through numerical simulations and analyses of experimental data. Both the numerical and experimental tests with wave gages, show that the directional spread of estimated spectra becomes narrower than that of the actual wave field and the value of the spectral peak is overestimated for the case of adverse currents. The extent of these distortions depends on the relative speed and direction of the current and waves. The relation of the error and these factors is summarized in the present study.

/pdf/the-effects-of-currents-on-estimations-of-directional-wave-jf3sz5jrvz.pdf

The effects of currents on estimations of directional wave spectra

Modification of extended maximum entropy principle method (EMEP) for estimating directional spectrum in incident and reflected wave field

Muddy bottom sediments in industrialized coastal areas are often quite enriched in contaminants and organic matter. It is important to study the processes that control fine sediment accumulation in these areas. In order to examine the relationship between hydrodynamic forcing and sediment characteristics in Baltimore Harbor, MD, USA, estimated wave-induced bottom shear stresses were compared with sediment mud content distributions. Wave fields in the harbor were simulated with a numerical wave hindcasting model, HISWA. Spatial distributions of expected wave-induced bottom shear stresses in four wind speed ranges were obtained by directionally averaging wave-induced bottom shear stress predictions, weighting each direction by its probability of occurrence based on wind statistics from a long term data set collected near the harbor. A negative relationship between mud content and wave-induced shear stress was clear only for the stronger wind cases that occurred less than 5% of the time. The results suggest that the distribution of muddy bottom sediments in the mainstem of Baltimore Harbor is controlled largely by high wind wave events that occur infrequently. INTRODUCTION Contaminated bottom sediments in coastal areas present one of the most serious problems to be solved for restoration of healthy coastal and estuarinc environments. It is quite important to study processes that control fine sediment accumulation patterns in the coastal zone because contaminant concentrations are highly correlated with mud content in the sediments. Thus, the movement of contaminants can be understood only by understanding the movement of fine particles (Dyer, 1989). Spatial patterns of fine particle accumulation in coastal areas may depend on several factors including proximity to sources of fine sediment as well as hydrodynamic conditions such as tidal currents, wave forcing, and so on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Port and Harbor Research Institute, Ministry of Transport, 3-1-1 Nagase, Yokosuka 239-0826, Japan, ; y_nakagawa@ipc.phd.go.jp e University of Maryland Center for Environmental Science, Horn Point Laboratory 3 Maryland Department of Natural Resources, Maryland Geological Survey

Yasuyuki Nakagawa

Papers

Numerical computations of the nonlinear energy transfer of gravity-wave spectra in finite water depths

Breakwater Damage in Okushiri Port Due to the Hokkaido Nansei-Oki Earthquake Tsunami

The effects of currents on estimations of directional wave spectra

Modification of extended maximum entropy principle method (EMEP) for estimating directional spectrum in incident and reflected wave field

Effect of Wind Waves on Distribution of Muddy Bottom Sediments in Baltimore Harbor, USA