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1.
Within the CLASH project, wave overtopping at the vertical seawall at Samphire Hoe was measured by HR Wallingford (HRW), and compared laboratory tests in 2 & 3 dimensions carried out at the University of Edinburgh and HRW. At Samphire Hoe, overtopping volumes were captured in three volumetric tanks capable of measuring wave-by-wave and total overtopping volumes. The three tanks were placed progressively farther back from the seawall edge so that the spatial distribution of the overtopping discharges could be determined. The field measurement equipment was successfully deployed on three occasions, and measured overtopping discharges ranged from that barely considered to be hazardous to the public to over q = 3.0 l/s/m. The 2d testing at Edinburgh was modelled at a scale of 1:40, and the 3d model at HRW was modelled at 1:20. For both sets of laboratory tests, a range of conditions, representative of the storm wave conditions and water levels, was reproduced in addition to a set of parametric conditions. The storm conditions allowed a direct comparison between the field and laboratory measurements, and the parametric conditions were used to test the generic overtopping behaviour of the structure. For both sets of laboratory tests, mean overtopping discharges and the spatial distribution were measured separately. Analysis of the distribution data relates the proportion of the discharge that has landed as a function of (x / Lo); where x is the distance behind the crest, and Lo is the offshore wavelength. Analysis of the field, 2d & 3d laboratory data, and empirical prediction methods have not identified any scale effects for overtopping discharges at vertical and near-vertical seawalls. 相似文献
2.
A one-dimensional high-resolution finite volume model capable of simulating storm waves propagating in the coastal surf zone and overtopping a sea wall is presented. The model (AMAZON) is based on solving the non-linear shallow water (NLSW) equations. A modern upwind scheme of the Godunov-type using an HLL approximate Riemann solver is described which captures bore waves in both transcritical and supercritical flows. By employing a finite volume formulation, the method can be implemented on an irregular, structured, boundary-fitted computational mesh. The use of the NLSW equations to model wave overtopping is computationally efficient and practically flexible, though the detailed structure of wave breaking is of course ignored. It is shown that wave overtopping at a vertical wall may also be approximately modelled by representing the wall as a steep bed slope. The AMAZON model solutions have been compared with analytical solutions and laboratory data for wave overtopping at sloping and vertical seawalls and good agreement has been found. The model requires more verification tests for irregular waves before its application as a generic design tool. 相似文献
3.
灾害性波浪是中国沿海地区最具破坏性的自然灾害之一。采用开源程序OpenFOAM中interFoam求解器,对低顶海堤（在风暴潮和海平面上升情况下所面临的不利工况）的孤立波越浪特性开展数值模拟研究。通过孤立波冲击海堤的基准算例,验证模型在模拟波浪爬升和越浪过程中大变形波面以及剧烈波浪力方面的精度。基于验证的数值模型,对孤立波在低顶海堤上的越浪特征以及防浪墙高度对越浪的影响开展参数化研究。结果表明堤顶超高减小导致更为剧烈的越浪。针对尚无低顶海堤孤立波越浪量经验公式的问题,提出新的适用于堤顶超高小或为0的孤立波越浪量经验公式。此外,研究发现增加防浪墙高度可有效减少越浪,但防浪墙所受的波浪力也增大。综合考虑防浪墙减少越浪以及自身所受波浪力,针对文中研究采用的海堤截面和波浪条件,建议无量纲防浪墙高度取为1.00。 相似文献
4.
Spatial distribution of random wave overtopping water behind coastal structures was investigated using a numerical model based on Reynolds-Averaged Navier-Stokes solver (RANS) and Volume of Fluid (VOF) surface capturing scheme (RANS-VOF). The computed spatial distributions of wave overtopping water behind the structure agree well with the measurements by Pullen et al (2008) for a vertical wall and Lykke Andersen and Burcharth (2006) for a 1:2 sea dike. A semi-analytical model was derived to relate spatial distribution of wave overtopping water behind coastal structures to landward ground level, velocity and layer thickness on the crest. This semi-analytical model agrees reasonably well with both numerical model results and measurements close to coastal structures. Our numerical model results suggest that the proportion of wave overtopping water passing a landward location increases with a seaward slope when it is less than 1:3 and decreases with a seaward slope when it gets steeper. The proportion of wave overtopping water passing a landward location increases with landward ground level and overtopping discharge. It also increases with the product of incident wave height and wavelength, but decreases with increasing relative structure freeboard and crest width. We also found that the extent of hazard area due to wave overtopping is significantly reduced by using a permeable structure crown. Findings in this study will enable engineers to establish the extent of hazard zones due to wave overtopping behind coastal structures. 相似文献
5.
This paper presents the application of the Improved Meshless Local Petrov Galerkin method with Rankine source (Sriram and Ma, 2012) Sriram and Ma (2012) for wave interaction with porous structure model. The mathematical model is based on a unified governing equation that incorporates both pure fluid and porous region. The porous flow model is based on the empirical resistance coefficients. The interface between the pure fluid and porous region is numerically treated using background nodes having the porosity information and interpolated over the particle using simplified finite difference interpolation method. The model is validated using the available experimental results for wave damping over the permeable bed. The developed model is used to analyse the different shape of the seawall such as flaring shaped seawall, recurve wall and vertical wall. Then the validated model is used for analysing the overtopping amount due to the effect of porous layer in-front of the different sea wall profile. Numerical expression for overtopping amount has been provided for the different configurations from the numerical model. 相似文献
6.
带胸墙斜坡堤越波量的试验研究 总被引：1，自引：0，他引：1
带胸墙斜坡式防波堤堤顶标高的合理确定，有赖于越波量的正确计算。本文基于水力学中流量系数的概念，建立越波量的计算公式。对影响流量系数的几个主要因素：波高、波陡、胸墙高、平台宽度、相对水深和护面结构等，进行了较系统的试验和讨论，提出了确定流量系数的经验公式。另外，还根据越波量的大小及越波波态，将堤分为：不越水堤、少量越水堤、越水堤及半潜堤四类，可作为合理确定堤顶标高时参考。 相似文献
7.
A series of hydraulic model tests has been carried out in a glass wave flume to investigate the influences of wave height, wave period, wave steepness, surf similarity parameter, roughness, layer thickness and porosity on wave run-up and overtopping of 1:2 sloped impermeable and permeable breakwaters fronted by a 1:10 gentle, smooth beach slope. The analysis of results involves the correlation between the overtopping energy transfer with the relative wall height and the relationship between wave run-up and overtopping rate. Further, measured wave run-up and overtopping rates are compared with the results given in the Shore Protection Manual (1984), Automated Coastal Engineering System (1992)and results of other investigators. 相似文献
8.
应用经CSPM法和黎曼解修正后的光滑粒子流体动力学(SPH)方法,建立了主动吸收无反射数值波浪水槽,研究波浪作用下多孔介质结构的水动力特性。流体运动控制方程采用N-S方程,多孔渗水结构内流体的运动控制方程考虑渗流力的影响。数值计算结果给出了水槽内不同位置测点的波面历时曲线和越浪量随时间变化曲线,并同试验结果和Philip Liu的数值计算结果进行了比较。并对一个波浪周期内斜坡堤多孔介质结构内外的速度场和压力分布进行了讨论分析。计算分析表明,数值计算波面较Philip Liu的计算结果与试验结果吻合更好。说明应用SPH方法建立的二维数学模型能够较好地模拟破碎波在多孔渗水斜坡上的爬坡和越浪。 相似文献
9.
The paper examines the variability of wave overtopping parameters predicted by numerical models based on non-linear shallow water equations, due to the boundary conditions obtained from wave energy density spectra. Free surface elevation time series at the boundary are generated using the principle of linear superposition of the spectral components. The components' phases are assumed to be random, making it possible to generate an infinite number of offshore boundary conditions from only one spectrum.A reference case was provided by carrying out overtopping tests on a simple concrete structure in a wave flume. Numerical tests using the measured free surface elevation at the toe of the structure were carried out. Three parameters were analysed throughout the paper: the overtopping discharge, the probability of overtopping and the maximum overtopping volume. These showed very good agreement between the numerical solver prediction and the overtopping measurements. Subsequently, the measured spectra at the toe were used to generate a population of reconstructed offshore boundary time series for each test, following a Monte Carlo approach. A sensitivity analysis determined that 500 tests were suitable to perform a statistical analysis on the predicted overtopping parameters. Results of these tests show that the variability in the predicted parameters is higher for the smaller number of overtopping waves in the modelled range and decreases significantly as overtopping becomes more frequent. The characteristics of the distributions of the predictions have been studied. The average value of the three parameters has been compared with the measurements. Although the accuracy is lower than that achieved by the model when the measured time series are used at the boundary, the prediction is still fairly accurate above all for the highest overtopping discharges. The distribution of the modelled probability of overtopping was found to follow a normal distribution, while the maximum value follows a GEV one. The overtopping discharge shows a more complex behaviour, values in the middle of the tested range follow a Weibull distribution, while a normal distribution describes the top end of the range better.Results indicate that when the probability of overtopping is smaller than 5%, a sensitivity analysis on the seeding of the offshore boundary conditions is recommended. 相似文献
10.
The conditions for energy flux, momentum flux and the resulting streaming velocity are analysed for standing waves formed in front of a fully reflecting wall. The exchange of energy between the outer wave motion and the near bed oscillatory boundary layer is considered, determining the horizontal energy flux inside and outside the boundary layer. The momentum balance, the mean shear stress and the resulting time averaged streaming velocities are determined. For a laminar bed boundary layer the analysis of the wave drift gives results similar to the original work of Longuet–Higgins from 1953. The work is extended to turbulent bed boundary layers by application of a numerical model. The similarities and differences between laminar and turbulent flow conditions are discussed, and quantitative results for the magnitude of the mean shear stress and drift velocity are presented. Full two-dimensional simulations of standing waves have also been made by application of a general purpose Navier–Stokes solver. The results agree well with those obtained by the boundary layer analysis. Wave reflection from a plane sloping wall is also investigated by using the same numerical model and by physical laboratory experiments. The phase shift of the reflected wave train is compared with theoretical and empirical models. 相似文献
11.
A two-dimensional vertical (2DV) non-hydrostatic boundary fitted model based on a Godunov-type shock-capturing scheme is introduced and applied to the simulation of waves from deep water up to the swash zone. The effects of shoaling, breaking, surf zone dissipation and swash motions are considered. The application of a Godunov-type shock-capturing algorithm together with an implicit solver on a standard staggered grid is proposed as a new approach in the 2DV simulation of large gradient problems such as wave breaking and hydraulic jumps. The complete form of conservative Reynolds averaged Navier–Stokes (RANS) equations are solved using an implicit finite volume method with a pressure correction technique. The horizontal advection of the horizontal velocity is solved by an explicit predictor–corrector method. Fluxes are predicted by an exact Riemann solver and corrected by a downwind scheme. A simple total variation diminishing (TVD) method with a monotonic upstream-centered scheme for conservation laws (MUSCL) limiter function is employed to eliminate undesirable oscillations across discontinuities. Validation of the model is carried out by comparing the results of the simulations with several experimental test cases of wave breaking and run-up and the analytical solution to linear short waves in deep water. Promising performance of the model has been observed. 相似文献
12.
13.
LI Xiao-liang 《中国海洋工程》2022,36(5):802-807
An empirical formula to predict overtopping discharge of vertical wall is presented, in which an expression similar to the solitary wave function is proposed to describe the rule of the influence of relative water depth. The formula is derived from performing an investigation to the well-known overtopping graphs of Goda, and for the sake of interest,the process of the derivation is detailed. To make clear the formula’s performance, relevant test datasets in the CLASH database are extracted to ex... 相似文献
14.
This work, which was largely a fruit of China's national marine hazard mitigation service, explicitly reveals the major mechanism of sea-dike failure during wave overtopping. A large group of wave-flume experiments were conducted for sea dikes with varying geometric characteristics and pavement types. The erosion and slide of the landward slope due to the combined effect of normal hit and great shear from overtopping flows was identified the major trigger of the destabilization of sea dikes. Once the intermittent hydrodynamic load and swash caused any deformation (bump or dent) of the pavement layer, pavement fractions (slabs or rubble) on the slope started to be initiated and removed by the water. The erosion of the landward slope was then gradually aggravated followed by entire failure within a couple of minutes. Hence, the competent velocity would be helpful evaluate the failure risk if as well accounted in standards or criteria. However, the dike top was measured experiencing the largest hydrodynamic pressure with a certain cap while the force on the wall increased rapidly as the overtopping intensity approached the dike-failure threshold. The faster increase of the force on the wall than on the landward slope yielded the sequencing of loads reaching hypothetic limits before failure as: dike top – top-mounted wall – landward slope. Therefore, beside the slide failure, the fatigue damage due to the instantaneous hydrodynamic impact might be another mechanism of the dike failure, which did not appear in the experiment but should be kept in mind. Instead of the widely adopted tolerable overtopping rate, a 0.117–0.424 m3/(m s) range of overtopping discharge and a 10 m/s overtopping velocity for the failure risk of typical sea dikes along China's coastlines were suggested, which enables the possible failure risk prediction through empirical calculations. The failure overtopping rate was identified strongly dependent on the pavement material, the landward slope and the dike-mounted wall but showed little variation with the width of the dike top. The flat concrete pavement and gentle landward slopes are suggested for the dike design and construction. For given configurations and hydrodynamic conditions in the experiment, the dike without the wall experienced less overtopping volume than those with the 1-m top-mounted wall. Meanwhile, the remove of the wall increased the failure overtopping rate, which means a certain increase of the failure criterion. Thus, care must be taken to conclude that the dike-mounted wall seems not an entirely appropriate reinforcement for the stability and safety of coastal protections. This should be further checked and discussed by researchers and engineers in the future. 相似文献
15.
Tsunami-like solitary waves impinging and overtopping an impermeable seawall: Experiment and RANS modeling 总被引：1，自引：0，他引：1
This study investigates tsunami-like solitary waves impinging and overtopping an impermeable trapezoidal seawall on a 1:20 sloping beach. New laboratory experiments are performed for describing three typical cases: a turbulent bore rushes inland and subsequently impacts and overtops the seawall (Type 1); a wave directly collapses on the seawall and then generates overtopping flow (Type 2); and, a wave straightforwardly overtops the seawall crown and collapses behind the seawall (Type 3). A two-dimensional volume of fluid (VOF) type model called the COBRAS (COrnell BReaking And Structure) model, which is based on the Reynolds-Averaged Navier–Stokes (RANS) equations and the k–ε turbulence closure solver, is validated by experimental data and then applied to investigate wave dynamics for which laboratory data are unavailable. Additionally, a set of numerical experiments is conducted to examine the dynamic wave acting force due to waves impacting the seawall. Effects of wave nonlinearity and freeboard are elucidated. Special attention is given to a distinct vortex evolutionary behavior behind the seawall, in which the dynamic properties of entrapped air-bubbles are briefly addressed experimentally and numerically. 相似文献
16.
Wave overtopping nearshore coastal structures, such as shore-parallel breakwaters, can significantly alter the current circulation and sediment transport patterns around the structures, which in turn affects the formation of tombolos and salients in the nearshore area. This paper describes the implementation of a wave overtopping module into an existing depth-averaged coastal morphological mode: COAST2D and model applications to investigate the effect of wave overtopping on the hydrodynamics and morphodynamics around a group of shore-parallel breakwaters. The hydrodynamic aspects of the model were validated against a series of laboratory conditions. The model was then applied to a study site at Sea Palling, Norfolk, UK, where 9 shore-parallel segmented breakwaters including 4 surface-piercing and 5 low-crested breakwaters are present, for the storm conditions in Nov 2006. The model results were compared with laboratory data and field measurements, showing a good agreement on both hydrodynamics and morphological changes. Further analysis of wave overtopping effect on the nearshore hydrodynamics and morphodynamics reveals that wave overtopping has significant impacts on the nearshore circulation, sediment transport and the resulting morphological changes within such a complex breakwater scheme under the storm and macro-tide conditions. The results indicate the importance of including the wave overtopping in modelling nearshore morphodynamics with the presence of coastal structures. 相似文献
17.
Derivation of unified wave overtopping formulas for seawalls with smooth,impermeable surfaces based on selected CLASH datasets 总被引：1，自引：0，他引：1
A set of unified formulas for prediction of the mean rate of wave overtopping at coastal structures with smooth, impermeable surfaces have been derived through the analysis of the selected CLASH datasets. The mean wave overtopping rate is expressed as the function of the significant wave height at the structural toe and the relative freeboard. The formulas are applicable for both vertical walls and inclined seawalls with smooth transition between them. The formulas are simple but cover the full range of water depth from the shoreline to deep water. The effects of the toe depth and the seabed slope on wave overtopping rate are duly incorporated in the formulas. Prediction performance of the new formulas is better than the EurOtop formulas for both vertical walls and inclined seawalls. 相似文献
18.
Numerical study of combined overflow and wave overtopping over a smooth impermeable seawall 总被引：1，自引：0，他引：1
A numerical wave flume is used to investigate the discharge characteristics of combined overflow and wave overtopping of impermeable seawalls. The numerical procedure computes solutions to the Reynolds-averaged Navier–Stokes equations and includes the generation of an irregular train of waves, the simulation of wave breaking and interaction with a sloping, impermeable wall. The numerical model is first tested against published experimental observations, approximate analytical solutions and empirical design formulae for the cases of pure overflow and pure overtopping. A sequence of numerical experiments simulating combined overflow and overtopping are described. The results are used to determine empirical discharge formulae of the form used in current practice. 相似文献
19.
Benchmark computations of wave run-up on single cylinder and four cylinders by naoe-FOAM-SJTU solver
The benchmark simulations of wave run-up on a fixed single truncated circular cylinder and four circular cylinders are presented in this paper. Our in-house CFD solver naoe-FOAM-SJTU is adopted which is an unsteady two-phase CFD code based on the open source package OpenFOAM. The Navier-Stokes equations are employed as the governing equations, and the volume of fluid (VOF) method is applied for capturing the free surface. Monochromatic incident waves with the specified wave period and wave height are simulated and wave run-up heights around the cylinder are computed and recorded with numerical virtual wave probes. The relationship between the wave run-up heights and the incident wave parameters are analyzed. The numerical results indicate that the presented naoe-FOAM-SJTU solver can provide accurate predictions for the wave run-up on one fixed cylinder and four cylinders, which has been proved by the comparison of simulated results with experimental data. 相似文献
20.
Riccardo Briganti Giorgio Bellotti Leopoldo Franco Julien De Rouck Jimmy Geeraerts 《Coastal Engineering》2005,52(12):351-1174
This paper describes a new station for full-scale measurement of wave overtopping at the Rome yacht harbour rubble mound breakwater in Ostia (Italy) and the results of the successful first measurement campaign carried out during the winter season 2003–2004. The equipment and the research activities were supported by the EU project CLASH, focusing on scale effects for wave overtopping at coastal structures. The site is characterized by a very small tidal range, a long shallow foreshore and depth-limited breaking waves which interact with a shallow sloping porous rock structure. Overtopping water is collected by a steel tank installed on the crown slab behind the parapet wall. The measurement of water level variation inside the tank by means of two pressure transducers allows the calculation of individual overtopping volumes. Incident waves, sea levels and wind are also measured. During seven independent storms, more than 400 individual overtopping events were recorded and about 86 h of valid data are available. This extensive dataset is presented, discussed and then used for comparison with two commonly used overtopping prediction formulae based on small-scale model tests showing their tendency to underestimate the prototype results. A strong correlation between the hourly mean overtopping discharge and corresponding maximum volume is also presented. The paper generally confirms the validity of the approach used in Troch et al. (2004) [Troch, P., Geeraets, J., Van de Walle, B., De Rouck, J., Van Damme, L., Allsop, W., Franco, L., 2004. Full-scale wave overtopping measurements on the Zeebrugge rubble mound breakwater. Coastal Engineering 51, 609–628] for field measurement of wave overtopping. 相似文献