Nearshore Compound Simulation by a Boussinesq-type Wave Model (original) (raw)
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Ocean Engineering, 2005
A non-linear wave propagation model, based on the higher order depth-integrated Boussinesqtype equations for breaking and non-breaking waves, was applied to predict irregular wave transformation in two horizontal dimensions. A new source function, adapted for the proposed equations, is introduced inside the computational domain, to generate the desired short-crested waves. The dissipation due to the roller is introduced in the momentum equation in order to simulate wave breaking. Bottom friction and sub-grid turbulent processes are also introduced in the model. At the open boundaries a damping layer is applied together with a radiation boundary condition. Model results are compared with experimental measurements, containing tests with normal or oblique to the shore long-and short-crested irregular waves. The comparisons show that the model is able to simulate successfully the non-linear evolution of a unidirectional or a multidirectional wave filed in the nearshore zone, under the effects of refraction, shoaling, and breaking.
A hydrodynamic model of nearshore waves and wave-induced currents
2011
In This study develops a quasi-three dimensional numerical model of wave driven coastal currents with accounting the effects of the wave-current interaction and the surface rollers. In the wave model, the current effects on wave breaking and energy dissipation are taken into account as well as the wave diffraction effect. The surface roller associated with wave breaking was modeled based on a modification of the equations by Dally and Brown (1995) and Larson and Kraus (2002). Furthermore, the quasi-three dimensional model, which based on Navier-Stokes equations, was modified in association with the surface roller effect, and solved using frictional step method. The model was validated by data sets obtained during experiments on the Large Scale Sediment Transport Facility (LSTF) basin and the Hazaki Oceanographical Research Station (HORS). Then, a model test against detached breakwater was carried out to investigate the performance of the model around coastal structures. Finally, the model was applied to Akasaki port to verify the hydrodynamics around coastal structures. Good agreements between computations and measurements were obtained with regard to the cross-shore variation in waves and currents in nearshore and surf zone.
Proceedings of Coastal Structures Conference 2019, 2019
An updated version of a 2-DH post-Boussinesq wave model is introduced. The model is wavenumber free and as far as the linear dispersion relation is concerned, the approach is exact. It is implemented for the wave propagation and transformation due to shoaling, refraction, diffraction, bottom friction, wave breaking, wave-structure interaction, reflection, wave-current interaction, etc. in nearshore zones and specifically inside ports and in the vicinity of coastal structures. Thorough validation of the model is attempted by comparisons with output from classic laboratory-scale wave flume experiments as well as analytical solutions. Physical cases of both regular and irregular wave fields are numerically reproduced with acceptable accuracy. Results concerning a case study in a characteristic Greek port setup are also presented and seem encouraging for realistic scale simulations.
Chapter 2 Frequency domain wave models in the nearshore and surf zones
Elsevier Oceanography Series, 2003
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CHAPTER 11 Vertically 2-D Nearshore Circulation Model
2010
A two layer undertow model is developed which consists of surface and inner layer. The surface layer defines breaking wave dynamics and the inner layer defines the mean fiow(circulation) and turbulence fields. The interface between two layers is determined by time and depth averaging of the mean water level and wave height in the surf zone (interface model), in which Reynolds stresses are taken into consideration as well as radiation stresses. The system of equations in the inner layer is derived by time averaging the mass and momentum equations over one wave period. Time and space averaging of these equations in the surface layer defines the surface boundary conditions of the mean flow field in the inner layer. Turbulence in the inner layer is discribed by the standard k — e model. The numerical calculation method is also discussed and model calibration is performed by comparing with the experiments by Stive and Wind (1985).
Numerical simulation of surf–swash zone motions and turbulent flow
2009
A two-dimensional numerical model was presented for the simulation of wave breaking, runup and turbulence in the surf and swash zones. The main components of the model are the Reynolds-Averaged Navier-Stokes equations describing the average motion of a turbulent flow, a k-e turbulence closure model describing the transformation and dissipation processes of turbulence and a volume of fluid technique for tracking the free surface motion. Nearshore wave evolution on a sloping bed, the velocity field and other wave characteristics were investigated. First, the results of the model were compared with experimental results for different surf zone hydrodynamic conditions. Spilling and plunging breakers were simulated and the numerical model investigated for different wave parameters. The turbulence field was also considered and the spatial and time-dependent variations of turbulence parameters were discussed. In the next stage of the study, numerical results were compared with two sets of experimental data in the swash zone. Generally, there is good agreement except for turbulence predictions near the breaking point where the model does not represent well the physical processes. On the other hand, turbulence predictions were found to be excellent for the swash zone. The model provides a precise and efficient tool for the simulation of the flow field and wave transformations in the nearshore, especially in the swash zone. The numerical model can simulate the surface elevation of the vertical shoreline excursion on sloping beaches, while swash-swash interactions within the swash zone are accounted for.
A numerical model of nearshore waves, currents, and sediment transport
Coastal Engineering, 2009
A two-dimensional numerical model of nearshore waves, currents, and sediment transport was developed. The multi-directional random wave transformation model formulated by Mase [Mase, H., 2001. Multi-directional random wave transformation model based on energy balance equation. Coastal Engineering Journal 43 (4) (2001) 317] based on an energy balance equation was employed with an improved description of the energy dissipation due to breaking. In order to describe surface roller effects on the momentum transport, an energy balance equation for the roller was included following Dally-Brown [Dally, W. R., Brown, C. A., 1995. A modeling investigation of the breaking wave roller with application to cross-shore currents. Journal of Geophysical Research 100(C12), 24873]. Nearshore currents and mean water elevation were modeled using the continuity equation together with the depth-averaged momentum equations. Sediment transport rates in the offshore and surf zone were computed using the sediment transport formulation proposed by Camenen-Larson
Proc. 1 st European IAHR Congress Edinburgh, http: …
Spectral wave energy models such as SWAN are widely used to make predictions of waves in deep and shallow water, incorporating the effects of wave interactions and transformations such as refraction, diffraction and breaking. To calculate nearshore processes such as wave runup on a wave-by-wave basis, phase-resolving shallow-water and Boussinesq-type models are more useful. However, these models are more computationally expensive and cannot be used in deep water. Therefore, a convenient solution is to use the output from a spectral energy analysis to create a wave input for a shallow-water / Boussinesq-type analysis in the nearshore. However, it is unclear how and where best to couple the models.