scholarly journals The wave overtopping load on landward slopes of grass-covered flood defences: Deriving practical formulations using a numerical model

2021 ◽  
pp. 104047
Author(s):  
Vera M. van Bergeijk ◽  
Jord J. Warmink ◽  
Suzanne J.M.H. Hulscher
Keyword(s):  
Numerical Model ◽  
Wave Overtopping

scholarly journals APPLICATION OF SMOOTHED PARTICLE HYDRODYNAMICS IN EVALUATING THE PERFORMANCE OF COASTAL RETROFIT STRUCTURES

2018 ◽  
pp. 109 ◽  
Author(s):  
Soroush Abolfathi ◽  
Dong Shudi ◽  
Sina Borzooei ◽  
Abbas Yeganeh-Bakhtiari ◽  
Jonathan Pearson
Keyword(s):  
Numerical Model ◽  
Smoothed Particle Hydrodynamics ◽  
Vertical Wall ◽  
Laboratory Data ◽  
Wave Structure ◽  
Base Case ◽  
Submerged Breakwater ◽  
Wave Overtopping ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This study develops an accurate numerical tool for investigating optimal retrofit configurations in order to minimize wave overtopping from a vertical seawall due to extreme climatic events and under changing climate. A weakly compressible smoothed particle hydrodynamics (WCSPH) model is developed to simulate the wave-structure interactions for coastal retrofit structures in front of a vertical seawall. A range of possible physical configurations of coastal retrofits including re-curve wall and submerged breakwater are modelled with the numerical model to understand their performance under different wave and structural conditions. The numerical model is successfully validated against laboratory data collected in 2D wave flume at Warwick Water Laboratory. The findings of numerical modelling are in good agreement with the laboratory data. The results indicate that recurve wall is more effective in mitigating wave overtopping and provides more resilience to coastal flooding in comparison to base-case (plain vertical wall) and submerged breakwater retrofit.

A numerical model of wave overtopping on seadikes

2010 ◽  
Vol 57 (8) ◽  
pp. 757-772 ◽  
Author(s):  
Thieu Quang Tuan ◽  
Hocine Oumeraci
Keyword(s):  
Numerical Model ◽  
Wave Overtopping

scholarly journals APPLICATION OF SMOOTHED PARTICLE HYDRODYNAMICS IN EVALUATING THE PERFORMANCE OF COASTAL RETROFIT STRUCTURES

2018 ◽  
Vol 1 (36) ◽  
pp. 109 ◽  
Author(s):  
Soroush Abolfathi ◽  
Dong Shudi ◽  
Sina Borzooei ◽  
Abbas Yeganeh-Bakhtiari ◽  
Jonathan Pearson
Keyword(s):  
Numerical Model ◽  
Smoothed Particle Hydrodynamics ◽  
Vertical Wall ◽  
Laboratory Data ◽  
Wave Structure ◽  
Base Case ◽  
Submerged Breakwater ◽  
Wave Overtopping ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This study develops an accurate numerical tool for investigating optimal retrofit configurations in order to minimize wave overtopping from a vertical seawall due to extreme climatic events and under changing climate. A weakly compressible smoothed particle hydrodynamics (WCSPH) model is developed to simulate the wave-structure interactions for coastal retrofit structures in front of a vertical seawall. A range of possible physical configurations of coastal retrofits including re-curve wall and submerged breakwater are modelled with the numerical model to understand their performance under different wave and structural conditions. The numerical model is successfully validated against laboratory data collected in 2D wave flume at Warwick Water Laboratory. The findings of numerical modelling are in good agreement with the laboratory data. The results indicate that recurve wall is more effective in mitigating wave overtopping and provides more resilience to coastal flooding in comparison to base-case (plain vertical wall) and submerged breakwater retrofit.

scholarly journals Numerical Analysis of Vertical Breakwater Stability under Extreme Waves

2020 ◽  
Vol 8 (12) ◽  
pp. 986
Author(s):  
Meng-Syue Li ◽  
Cheng-Jung Hsu ◽  
Hung-Chu Hsu ◽  
Li-Hung Tsai
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Rear Side ◽  
Phase Lag ◽  
Back Side ◽  
Extreme Waves ◽  
Wave Overtopping ◽  
Overturning Stability ◽  
Vertical Breakwater ◽  
Caisson Breakwater

The purpose of this study is to perform a numerical simulation of caisson breakwater stability concerning the effect of wave overtopping under extreme waves. A numerical model, which solves two-dimensional Reynolds-averaged Navier–Stokes equations with the k−ε turbulence closure and uses the volume of fluid method for surface capturing, is validated with the laboratory observations. The numerical model is shown to accurately predict the measured free-surface profiles and the wave pressures around a caisson breakwater. Considering the dynamic loading on caisson breakwaters during overtopping waves, not only landward force and lift force but also the seaward force are calculated. Model results suggest that the forces induced by the wave overtopping on the back side of vertical breakwater and the phase lag of surface elevations have to be considered for calculating the breakwater stability. The numerical results also show that the failure of sliding is more dangerous than the failure of overturning in the vertical breakwater. Under extreme waves with more than 100 year return period, the caisson breakwater is sliding unstable, whereas it is safe in overturning stability. The influence of wave overtopping on the stability analysis is dominated by the force on the rear side of the caisson and the phase difference on the two ends of caisson. For the case of extreme conditions, if the impulse force happens at the moment of the minimum of load in the rear side, the safety factor might decrease significantly and the failure of sliding might cause breakwater damage. This paper demonstrates the potential stability failure of coastal structures under extreme sea states and provides adapted formulations of safety factors in dynamic form to involve the influence of overtopping waves.

Numerical Simulation of Wave Overtopping of Breakwater Armored with Porous Layers and Water-Structure Impaction

2012 ◽  
Vol 226-228 ◽  
pp. 1255-1259
Author(s):  
Zong Liu Huang ◽  
Peng Zhi Lin
Keyword(s):  
Porous Media ◽  
Numerical Model ◽  
Wave Height ◽  
Stokes Equations ◽  
Water Structure ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Wave Overtopping ◽  
Impact Forces ◽  
The Impact

A numerical model has been developed to study wave overtopping of permeable units protected breakwater and water-structure impactions. The numerical model solves the Reynolds Averaged Navier-Stokes equations outside of porous media and solves the spatially averaged Navier-Stokes equations in porous media, respectively. The numerical model is first validated by experimental data. The validated model is then employed to investigate the breaking wave overtopping porous media protected breakwater. The overtopping discharge and impact forces on the structures behind the crown wall in different wave conditions are studied. The increase of wave height brings increasing maximum overtopping discharges and different spatial distribution of water behind the crown wall. The impact forces on the structures are determined by both incident wave height and relative positions of the structures.

scholarly journals Hydrodynamic Modelling of Wave Overtopping over a Block-Covered Flood Defence

2022 ◽  
Vol 10 (1) ◽  
pp. 89
Author(s):  
Luuk Barendse ◽  
Vera M. van Bergeijk ◽  
Weiqiu Chen ◽  
Jord J. Warmink ◽  
Aroen Mughal ◽  
...  
Keyword(s):  
Numerical Model ◽  
Porous Layer ◽  
Hydrodynamic Condition ◽  
Hydrodynamic Conditions ◽  
Physical Test ◽  
Wave Overtopping ◽  
Physical Tests ◽  
Run Up ◽  
Resistance Coefficients ◽  
Flow Velocities

Wave overtopping can cause erosion on the landward slope due to high flow velocities and turbulence that cause high stresses on the cover. Innovative block revetments such as Grassblocks protect the subsoil of the dike against erosion. The blocks are permeable, which reduces the flow velocity and the pressures along the landward slope. The performance of these blocks is assessed in physical tests, which provides insights into the stability of the blocks. However, such experiments are expensive and accurate measurements are difficult due to highly turbulent conditions. Therefore, the goal of this study is to determine the hydrodynamic conditions at the dike cover caused by the wave run-up on the seaward slope and by the overtopping flow over the crest and landward slope. The geometry and wave conditions from the physical test at the Deltares Delta flume are implemented in an OpenFOAM® numerical model. Using the porousWaveFoam solver, a porous layer on the crest and landward slope is implemented, where the flow resistance of this porous layer largely depends on the resistance coefficients α [-] and β [-]. The numerical model is calibrated based on resistance coefficients as introduced earlier in the literature, which showed that the resistance coefficients of α=500 and β=2.0 performed best for the peak flow velocities and the peak pressures. The numerical model is evaluated by using these resistance coefficients in other time series of the physical tests. The evaluated model is then used to determine the hydrodynamic conditions on the landward slope, which showed that the pressure was the most influential hydrodynamic condition at the time of failure. Finally, the model showed that a porosity of n=0.6 and the porous layer thickness η=36mm reduced the peak pressure the most.

scholarly journals MODELLING OF WAVE OVERTOPPING AT DIKES USING OPENFOAM

2020 ◽  
pp. 27
Author(s):  
Weiqiu Chen ◽  
Jord Warmink ◽  
Marcel van Gent ◽  
Suzanne Hulscher
Keyword(s):  
Numerical Model ◽  
Physical Model ◽  
Turbulence Model ◽  
Wave Breaking ◽  
Model Calibration ◽  
Empirical Methods ◽  
Empirical Formulas ◽  
Wave Overtopping ◽  
Calibration And Validation ◽  
Physical Model Tests

The average overtopping discharge is an important parameter for the design of flood defences. Several empirical formulas are available for predicting the overtopping discharge at dikes. However, these empirical formulas often have their specific applicable conditions. To complement with the empirical methods, a numerical model has been developed using the open source CFD package OpenFOAM to model the wave overtopping at dikes. Systematic calibration and validation of the numerical model are performed. The influences of the mesh, solver, turbulence model and roughness height on the modelled results of the average overtopping discharge have been investigated during the model calibration. The simulations show that the turbulence model increases the accuracy of the numerical model for predicting the average overtopping discharge under wave breaking conditions. The calibrated model is then validated by comparing the modelled average overtopping discharges with the measured ones from the physical model tests. Results show that the OpenFOAM model is capable of predicting the average overtopping discharge accurately at dikes that have a smooth straight waterside slope.

scholarly journals Modelling the Wave Overtopping Flow over the Crest and the Landward Slope of Grass-Covered Flood Defences

2020 ◽  
Vol 8 (7) ◽  
pp. 489
Author(s):  
Vera M. van Bergeijk ◽  
Jord J. Warmink ◽  
Suzanne J. M. H. Hulscher
Keyword(s):  
Shear Stress ◽  
Numerical Model ◽  
Flow Velocity ◽  
Normal Stress ◽  
High Pressures ◽  
Maximum Shear Stress ◽  
Maximum Flow ◽  
Maximum Pressure ◽  
Grass Cover ◽  
Wave Overtopping

The wave overtopping flow can exert high hydraulic loads on the grass cover of dikes leading to failure of the cover layer on the crest and the landward slope. Hydraulic variables such as the near bed velocity, pressure, shear stress and normal stress are important to describe the forces that may lead to cover erosion. This paper presents a numerical model in the open source software OpenFOAM® to simulate the overtopping flow on the grass-covered crest and slope of individual overtopping waves for a range of landward slope angles. The model provides insights on how the hydraulic forces change along the profile and how irregularities in the profile affect these forces. The effect of irregularities in the grass cover on the overtopping flow are captured in the Nikuradse roughness height calibrated in this study. The model was validated with two datasets of overtopping tests on existing grass-covered dikes in the Netherlands. The model results show good agreement with measurements of the flow velocity in the top layer of the wave, as well as the near bed velocity. The model application shows that the pressure, shear stress and normal stress are maximal at the wave front. High pressures occur at geometrical transitions such as the start and end of the dike crest and at the inner toe. The shear stress is maximal on the lower slope, and the normal stress is maximal halfway of the slope, making these locations vulnerable to cover failure due to high loads. The exact location of the maximum forces depends on the overtopping volume. Furthermore, the model shows that the maximum pressure and maximum normal stress are largely affected by the steepness of the landward slope, but the slope steepness only has a small effect on the maximum flow velocity and maximum shear stress compared to the overtopping volume. This new numerical model is a useful tool to determine the hydraulic forces along the profile to find vulnerable points for cover failure and improve the design of grass-covered flood defences.

scholarly journals SETTLEMENT OF ROCK SEAWALL ON ERODING FORESHORE OF SAND BEACH

2018 ◽  
pp. 39
Author(s):  
Hyun Dong Kim ◽  
Nobuhisa Kobayashi
Keyword(s):  
Numerical Model ◽  
Detailed Analysis ◽  
Test Series ◽  
Swash Zone ◽  
Sand Beach ◽  
Wave Overtopping ◽  
Comparison Test ◽  
The Cross

The effectiveness of structures placed on the foreshore of a sand beach and a berm was tested and confirmed to reduce wave overtopping and sand overwash, expanding upon the previous comparison test conducted by Kim et al. (2016) with using sand and two different sizes of stones shown in Table 1. Test contains two test series of a rock seawall (Series R) and a dune with a buried seawall (Series B) on the foreshore as shown initial of the two structures in Figure 1 which reduced both wave overtopping and sand overwash even after its deformation. Damage was inflicted upon these two structures which seems to be caused by either stone displacement or structure settlement. To find out which was the case, detailed analysis has been conducted, along with an application of the cross-shore numerical model CSHORE (Kobayashi 2016) for the purpose of simulating sand and stone interactions in the swash zone on the sand beach.

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