Numerical Simulation of Solitary Waves Propagating on Stepped Slopes Beaches (original) (raw)
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Numerical Modelling and experiments for solitary wave shoaling and breaking over sloping beach
This research deals with the validation of fluid dynamic models, used for simulating shoaling and breaking solitary waves on slopes, based on experiments performed at the Ecole Supérieure d'Ingénieurs de Marseille's (ESIM) laboratory. A separate paper, also presented at this conference, reports on experiments. In a first part of this work, a fully nonlinear potential flow model based on a Boundary Element Method (BEM) developed at the University of Rhode Island (URI), is used to generate and propagate solitary waves over a slope, up to overturning, in a setup closely reproducing the laboratory tank geometry and wavemaker system. The BEM model uses a boundary integral equation method for the solution of governing potential flow equations and an explicit Lagrangian time stepping for time integration. In a second part, several Navier-Stokes (NS) models, developed respectively at TREFLE-ENSCPB, IMFT, IRPHE and LSEET are initialized based on the BEM solution and used for modeling breaking solitary waves in a finely discretized region encompassing the top of the slope and the surfzone. The NS models are based on the Volume of Fluid Method (VOF). This paper mostly deals with the first part, which includes calibration and comparison of BEM results with experiments, for the generation of solitary waves in the physical wave tank. Thus, parameters of the physical wave tank were numerically matched, including tank geometry and motion of the wavemaker paddle corresponding to the generation of solitary waves. Use and coupling of the BEM and VOF models for the simulation of solitary wave breaking is discussed in the paper.
The Breaking and Run-Up of Solitary Waves on Beaches
Coastal Engineering 1992, 1993
A high accuracy boundary element method is used to compute the propagation of solitary waves from a constant depth region onto a plane slope. Initial wave heights range from H/h = 0.06 to 0.775, slopes between 1:35 and 1:1.73 (30°) have been investigated. The prebreaking shoaling shows very different characteristics on gentle slopes (1:20 and less) and on steeper slopes. A diagram constructed on the basis of a large number of numerical experiments gives a simple limit between which waves break on which slopes and which not. Typical examples of the range of wave behavior are shown. Waves that do not break at run up often break during run down. The velocity fields for the two types of breaking are compared and found to be very different. A simple explanation for this is offered.
Generation and propagation of solitary wave over a steep sloping beach
2008
A numerical model has been developed to solve the unsteady Navier–Stokes equations together with a convective equation describing the flow surface profile and with the appropriate boundary conditions. In order to generate nonlinear solitary wave on constant depth, an appropriate mass source term is added for the equation of mass conservation in the internal flow region. This model is implemented in the industrial Computational Fluid Dynamics code : PHOENICS (Parabolic Hyperbolic Or Elliptic Numerical Integration Code Series). The numerical wave generation is validated by comparisons of numerical results with the analytical solutions and show that the solitary wave is very accurately generated. The propagation of the solitary wave in constant water depth indicated that the wave preserved its permanent form and the same wave velocity. This model is then used to simulate the nonbreaking runup and rundwon caused by the solitary wave passing over impermeable steep plane beach. The numeri...
Numerical Modeling and Experiments for Solitary Wave Shoaling and Breaking over a Sloping Beach
2004
This research deals with the validation of fluid dynamic models, used for simulating shoaling and breaking solitary waves on slopes, based on experiments performed at the Ecole Supérieure d'Ingénieurs de Marseille's (ESIM) laboratory. A separate paper, also presented at this conference, reports on experiments. In a first part of this work, a fully nonlinear potential flow model based on a Boundary Element Method (BEM) developed at the University of Rhode Island (URI), is used to generate and propagate solitary waves over a slope, up to overturning, in a set-up closely reproducing the laboratory tank geometry and wavemaker system. The BEM model uses a boundary integral equation method for the solution of governing potential flow equations and an explicit Lagrangian time stepping for time integration. In a second part, several Navier-Stokes (NS) models, developed respectively at MASTER-ENSCPB, IMFT, IRPHE, LSEET, and LaSAGeC, are initialized based on the BEM solution and used for modeling breaking solitary waves in a finely discretized region encompassing the top of the slope and the surfzone. The NS models are based on the Volume of Fluid Method (VOF). This paper mostly deals with the first part, which includes calibration and comparison of BEM results with experiments, for the generation of solitary waves in the physical wave tank. Thus, parameters of the physical wave tank were numerically matched, including tank geometry and motion of the wavemaker paddle corresponding to the generation of solitary waves. Use and coupling of the BEM and VOF models for the simulation of solitary wave breaking is discussed in the paper.
Water, 2019
An experimental investigation is performed to elucidate the variations of accelerations and pressure gradients in the external stream of retreating flow during the run-down phase of a non-breaking solitary wave, propagating over a 1:3 sloping beach. Two solitary waves that have the incident wave heights (H0) of 2.9 and 5.8 cm, with respective still water depths (h0) of 8.0 and 16.0 cm (Cases A and B), were generated in a wave flume, resulting in the incident wave-height to water-depth ratios (H0/h0) being identically equal to 0.363. The latter case was only used to highlight the non-dimensional features of the wave celerity, the time history of horizontal velocity and the breaker type, which all exhibit similarity to those of the former. Two flow visualization techniques such as particle trajectory method and fluorescent dye strip and a high-speed particle image velocimetry (HSPIV) were utilized to provide the flow images and velocity fields. Based on the ensemble-averaged velocity ...
Numerical Simulation for Wave Breaking on Bar/Step-Type Beach Profile
Journal of Coastal Research, 2015
A two-dimensional numerical model was developed to simulate wave breaking on a barred/stepped beach profile. The volume of fluid with piecewise linear interface calculation (VOF/PLIC) is employed to a track-free surface configuration. The embedding (EB) method is used to describe complex bottom topography without imposing boundary conditions on the bottom. The present model shows significant improvement for describing both wave profile and flow fields for spilling breakers when compared with laboratory observations. Based on numerical results, flow characteristics of the free surface profile, mean velocities, vorticities and turbulence transports under spilling breakers traveling over a bar/steptype beach profile were discussed.
Procedia Engineering, 2015
The solitary wave run-up in the presence of an onshore coastal cliff is investigated using the Smoothed Particle Hydrodynamics (SPH) method. A composite topography made of a steep slope, a gentle beach and a steep coastal cliff was used in the experimental and numerical studies to represent real life scenarios. Comparison with laboratory measurements shows that the SPH model is able to capture the evolution and run-up of solitary waves for both non-breaking and slight breaking cases with reasonable accuracy.
Numerical study of the hydrodynamics of regular waves breaking over a sloping beach
European Journal of Mechanics B-fluids, 2011
In the last three decades, great improvements have been ∧ made towards knowledge of the hydrodynamics and general processes occurring in the surf zone, widely affected by the breaking of the waves. Nevertheless, the turbulent flow structure is still very complicated to investigate. The aim of this work is to present and discuss the results obtained by simulating two-dimensional breaking waves by solving the Navier-Stokes equations, in air and water, coupled with a dynamic subgrid scale turbulence model (Large Eddy Simulation, LES). First, the ability of the numerical tool to capture the crucial features of this complicated turbulent two-phase flow is demonstrated. Numerical results are compared with experimental observations provided by Kimmoun and Branger (2007) [24]. Spilling/plunging breaking regular waves are considered. Generally, there is good agreement and the model provides a precise and efficient tool for the simulation of the flow field and wave transformations in the nearshore.
Two-way coupled long wave - RANS model: Solitary wave transformation and breaking on a plane beach
Coastal Engineering, 2016
A two-way coupled long wave to Reynolds-averaged Navier-Stokes (RANS) wave model named 2CLOWNS is introduced in this study and its numerical procedure is described in detail. The model is applied to solitary wave transformation and breaking on plane beaches with slopes 1/100, 1/60, 1/35 and 1/20. Two-way coupling was verified for test cases of pure solitary wave reflection on a flat bed, and wave transformation on slopes including rundown. The algorithm becomes sufficiently robust when a no gradient boundary condition on the vertical velocities is applied, the local wave height and slope are sufficiently small, and the coupling depths are sufficiently large. Suggested limits to the local wave height and slope are outlined. Characteristics of shoaling prior to breaking are analysed in detail for the long wave model. Optimal depths for coupling to the RANS model are found that approximately correspond to the transition from gradual shoaling to rapid shoaling. An expression that estimates this location is presented based on a nondimensional slope parameter. Overall, 2CLOWNS is shown to approximate shoaling and breaking characteristics in comparison with theory, physical experiments and other numerical analyses. The post-breaking behaviour and wave shape approximate theoretical descriptions and experimental observations including the touchdown of the plunging jet and resulting splashup. Velocity profiles are shown to be considerably different to ones based on depth-integrated models just prior to wave breaking and thereafter. 2CLOWNS allows for more reliable simulations when computing wave propagation from far offshore towards the coast in reduced computational time compared with full RANS simulations under the appropriate conditions outlined in this study.