Numerical Simulations of Wind Wave Growth under a Coastal Wind Jet through the Kanmon Strait

Abstract The development of a coastal wind jet flowing through the Kanmon Strait and the associated wind wave growth are investigated from a case study on 24–26 July 1999. This study presents a realistic example of fetch-limited wave growth under a developing wind jet outflowing from a terrestrial gap of a coast. A series of numerical simulations are used by one-way coupling between a mesoscale meteorological model and a shallow-water wave model with high spatiotemporal resolutions of 2 km and 1 h. The simulated fields of wind and wave are compared with satellite and in situ observations and it is confirmed that they coincide with observations. A complete picture of the wind jet is obtained from the wind simulations, and wave simulations demonstrate the areal extent of higher waves growing with the development of the wind jet. The wind maximum region is localized and extends downwind. The maximum wave height region is highly localized but located more downwind of the wind speed maximum. The high wave region completely reaches the southern coast of the Korean Peninsula before the strong wind. In the lee of the islands, waves are blocked. The conventional fetch growth of waves holds in waves at the more upwind locations than the highest wave region. The forecasting of localized waves under a coastal wind jet is a case in which adequately high spatiotemporal resolution is required for both the wave simulation and wind input.

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A HYBRID METHOD TO COMBINE WAVE PENETRATION AND LOCAL WAVE GROWTH IN LARGE HARBOR BASINS

Coastal Engineering Proceedings ◽

10.9753/icce.v36.papers.46 ◽

2018 ◽

pp. 46

Author(s):

Gerbrant Van Vledder

Keyword(s):

Hybrid Method ◽

Wind Wave ◽

Wave Model ◽

Wind Forcing ◽

Wind Effect ◽

Wave Growth ◽

The North ◽

Local Wave ◽

Wave Conditions ◽

Diffraction Effects

This paper describes a hybrid method to determine the wave conditions in large harbor basins were wave propagation and local wave growth by wind are both of relevance. The method was developed to include the effects of diffraction and wind wave growth in the assessment of design wave conditions that so far cannot be computed within one wave model. The diffraction effects are computed with a phase-resolving wave penetration model, and the wind effect is computed with a phase averaged spectral wave model. The method accounts for the effect the local wind wave growth occurs on top of the penetrating wave field. To isolate the wind wave growth, two model runs are performed with the phase-average model. One run includes wind forcing, whereas in the other run wind forcing is switched off. Subtracting the results of both methods isolates the local wave growth. The method is illustrated with a hypothetical example for the Port of IJmuiden, located along the North Sea coast of the Netherlands. In addition, an overview is given of the physical processes relevant for the determination of design wave conditions in large harbor basins. The assumptions of the hybrid method are discussed and recommendations are given for further improvements.

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

Journal of Fluid Mechanics ◽

10.1017/s0022112010004921 ◽

2011 ◽

Vol 669 ◽

pp. 178-213 ◽

Cited By ~ 30

Author(s):

ELODIE GAGNAIRE-RENOU ◽

MICHEL BENOIT ◽

SERGEI I. BADULIN

Keyword(s):

Numerical Simulations ◽

Wave Energy ◽

Water Waves ◽

Wind Wave ◽

Wind Waves ◽

Initial Growth ◽

Limited Growth ◽

Wave Growth ◽

Wide Range ◽

Wind Sea

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, Sin, and two methods for calculating the nonlinear transfer term Snl (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, Sin, Sdiss and Snl, 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 αss = 0.68 ± 0.1.Further prospects of wind-wave modelling in the context of the presented weakly turbulent scaling are discussed.

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WAVE CLIMATE OF THE BLACK SEA’S COASTAL WATERS DURING THE LAST THREE DECADES

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b943584ab71.87772537 ◽

2017 ◽

Author(s):

Fedor Gippius ◽

Stanislav Myslenkov ◽

Elena Stoliarova ◽

...

Keyword(s):

Wind Speed ◽

Cell Size ◽

Coastal Waters ◽

Wind Wave ◽

Spatial Scales ◽

Wave Model ◽

Wave Climate ◽

Computational Grid ◽

Coastal Areas ◽

Wave Parameters

This study is focused on the alterations and typical features of the wind wave climate of the Black Sea’s coastal waters since 1979 till nowadays. Wind wave parameters were calculated by means of the 3rd-generation numerical spectral wind wave model SWAN, which is widely used on various spatial scales – both coastal waters and open seas. Data on wind speed and direction from the NCEP CFSR reanalysis were used as forcing. The computations were performed on an unstructured computational grid with cell size depending on the distance from the shoreline. Modeling results were applied to evaluate the main characteristics of the wind wave in various coastal areas of the sea.

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