Improved coastal boundary condition for surface water waves (original) (raw)
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This work presents a simple and relatively quick methodology to obtain the nearshore wave angle. The method is especially valuable for curvilinear coasts where Snell's law may provide excessively inaccurate results. We defined a correction factor, K, that depends on the geometry of the coast and on the wave climate. The values of this coefficient were obtained minimizing the differences with a sophisticated numerical model. The limitations and performance of the methodology are further discussed. The procedure was applied to a beach in Southern Spain to analyze the influence of shoreline geometry on nearshore wave directionality. Offshore and nearshore distributions of wave period and directions were analyzed, and the results showed that the geometry of the coast played a crucial role in the directionality of the nearshore waves, which also plays an important role in hydrodynamics. The methodology presented here is able to analyze and quantify the importance of this directionality without a noticeable computational cost, even when a long time series of wave data are considered. Hence, this methodology constitutes a useful and efficient tool for practical applications in Coastal and Ocean Engineering, such as sedimentary, wave energy, and wave climate studies.
Numerical study of propagation of ship waves on a sloping coast
Ocean Engineering, 2006
The aim of this paper is to investigate the propagation of ship waves on a sloping coast on the basis of results simulated by a 2D model. The governing equations used for the present model are the improved Boussinesq-type equations. The wave breaking process is parameterized by adding a dissipation term to the depth-integrated momentum equation. To give the boundary conditions at the ship location, the slender-ship approximation is used. It was verified that, although ship waves are essentially transient, the Snell's law can be applied to predict crest orientation of the wake system on a sloping coast. Based on simulated results, an applicable empirical formula to predict the maximum wave height on the slope is introduced. The maximum wave height estimated by the proposed method agrees well with numerical simulation results.
Optimal estimations of directional wave conditions for nearshore field studies
Continental Shelf Research, 2020
Accurate directional wave conditions at shallow water are crucial for nearshore field studies and necessary as boundary conditions for morphodynamic models. However, obtaining reliable results for all wave parameters can be challenging, particularly regarding wave direction. Here, the accuracy of two global hindcast models and propagation of measured wave conditions using linear wave theory or the SWAN wave model (forced by integrated wave parameters or 2D spectra) is assessed to obtain directional wave conditions at shallow water for Castelldefels beach, Northwest Mediterranean Sea. Results are analyzed using different statistical error parameters and for different wave climates (shore-normal, shore-oblique and bimodal). The analysis shows that global hindcast models correctly predict the trends in wave height and mean wave period but predictions for mean wave direction are only accurate for shore-normal waves. Linear wave theory provides good results for wave height but underestimates refraction, resulting in significant errors in mean wave direction for shore-oblique waves. Finally, SWAN forced with 2D spectra results in the most accurate predictions for all wave parameters. When using integrated wave parameters as boundary conditions, the results for wave height and mean period stay the same whilst the errors in peak period and mean direction worsen for shore-oblique and bimodal wave climates. The reason is that for these wave conditions the directional spectrum constructed out of integrated wave parameters does not resemble the actual directional spectrum.
Numerical Investigation of Wave Fields and Currents in a Coastal Engineering Case Study
2018
In this paper, we present a Boussinesq type model which is able to simulate wave fields and nearshore currents in coastal regions characterized by morphologically complex coastal lines and irregular seabed and by the presence of coastal structures. The proposed model solves the integral contravariant form of the fully nonlinear Boussinesq equations, from deep water up to just seaward of the surf zones, and the non-linear shallow water equations, in the surf zone, on curvilinear boundary conforming grids. By the proposed model, a detailed representation is carried out of the hydrodynamic phenomena which contribute to generate the silting process at the entrance of the Cetraro harbour (Italy). Furthermore, the effects produced by the placement of a groin updrift of the head of the main jetty on coastal hydrodynamics and sediment transport are evaluated.
COASTAL WAVE MODELLING VALIDATION USING NEW FIELD TECHNIQUES
2000
Traditionally wave measurements in coastal areas are made using either wave buoys or pressure sensors deployed at the bottom. In general these equipments work included in monitoring networks in order to support wave climatologic programs. They are also frequently deployed for harbor management purposes. However the collected and saved data are limited for scientific purposes especially in order to make
A comparison of two different types of shoreline boundary conditions
Computer Methods in Applied Mechanics and Engineering, 2002
Two different types of shoreline boundary conditions which can be used in either wave-resolving or wave-averaging models of waves and currents propagation in the nearshore are compared here. The two techniques are essentially different: in the first case the velocity of the shoreline is obtained by the momentum equation and the shoreline position is tracked by changing the grid position, while in the other case the velocity of the shoreline is obtained by a modified Riemann solver and the shoreline is defined as an interface between dry and wet fixed grid points. A number of test cases are described to compare the performance of the two techniques. (M. Brocchini). 0045-7825/02/$ -see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 4 5 -7 8 2 5 ( 0 2 ) 0 0 3 9 2 -4
A third-generation wave model for coastal regions-1
1999
Abstract. A third-generation numerical wave model to compute random, short-crested waves in coastal regions with shallow water and ambient,currents (Simulating Waves Nearshore (SWAN)) has been developed, implemented, and validated. The model is based on a Eulerian formulation,of the discrete spectral balance of action density that accounts,for refractive propagation,over arbitrary bathymetry,and current fields. It is driven by boundary conditions and local
MODELLING AND MEASURING WAVES IN COASTAL WATERS
Coastal Engineering 2006 - Proceedings of the 30th International Conference, 2007
We investigate some aspects of wave-current interaction in the modelling and observations of waves and currents in the Irish Sea. The interaction of waves and currents through the surface and bottom stress, as well as refraction of waves by currents, is included in a coupled wave-current model. Long-term measurements of currents and waves, starting in November 2002, are being made in the Liverpool Bay Coastal Observatory in the Irish Sea. The large tidal range, relatively shallow depth and waves up to 5m suggest significant wave-current interactions will occur here and the measurements should provide a good test of coupled hydrodynamic-wave models. Some of the problems of getting observational data to validate or challenge these models are discussed.