scholarly journals WAVE OVERTOPPING AT DYKES WITH TOPPED VERTICAL WALL - IMPACTS OF OBLIQUE WAVE ATTACK

2012 ◽  
Vol 1 (33) ◽  
pp. 60
Author(s):  
Nils B. Kerpen ◽  
Torsten Schlurmann
Keyword(s):  
Numerical Models ◽  
Vertical Wall ◽  
Coastal Protection ◽  
Wave Spectra ◽  
Wave Overtopping ◽  
Oblique Wave ◽  
Wave Basin ◽  
Vertical Walls ◽  
The Mean ◽  
Analytical Approaches

Hydraulic model tests at a scale of 1:10 are carried out in a 40 m x 25 m wave basin with a state-of-the-art 3D wave generator in order to collect wave overtopping data at vertical walls and dykes with topped vertical walls. Wave conditions in the near field of the structures, velocities under waves and the mean overtopping discharge are measured. The experiments have been commissioned by the Lower Saxony Water Management, Coastal Defense and Nature Conservation Agency (NLWKN) with the purpose to deliver essential overtopping data for validation of numerical models. Two main geometries are analyzed – each for two specific wave spectra. Overtopping rates are investigated with respect to the remaining freeboard height Rc and the influence of oblique wave attack β{0°, 10°, 30°, 40°, 50°, 60°}. Results are compared with existing analytical approaches. As expected for this special geometrical coastal protection structure, it is examined that overtopping discharges increase with decreasing remaining freeboard. Intensity of the reduction is more dependent on the wave spectra than on the dyke geometry. Mean wave overtopping rate increases with decreasing relative water depth Hm0/d directly in front of the vertical wall. Furthermore, the mean wave overtopping rates decrease with an increasing angle of wave attack β. The correlation between mean wave overtopping rate and freeboard height is given in four newly adapted design formulas, describing the overtopping performance of the two discussed dyke geometries with topped vertical walls.

scholarly journals VERTICAL SEA WALL CREST MODIFICATIONS FOR OVERTOPPING

2018 ◽  
pp. 71
Author(s):  
Dogan Kisacik ◽  
Gulizar Ozyurt Tarakcioglu ◽  
Cuneyt Baykal ◽  
Gokhan Kaboglu
Keyword(s):  
Urban Areas ◽  
Vertical Wall ◽  
Breaking Wave ◽  
Limited Information ◽  
Coastal Structures ◽  
Wave Overtopping ◽  
Wave Basin ◽  
First Results ◽  
Set Up ◽  
Sea Wall

Crest modifications such as a storm wall, parapet or a bullnose are widely used to reduce the wave overtopping over coastal structures where spatial and visual demands restrict the crest heights, especially in urban areas. Although reduction factors of these modifications have been studied for sloped structures in EurOtop Manual (2016), there is limited information regarding the vertical structures. This paper presents the experimental set-up and first results of wave overtopping tests for a vertical wall with several different super structure types: a) seaward storm wall, b) sloping promenade, c) landward storm wall, d) stilling wave basin (SWB), e) seaward storm wall with parapet, f) landward storm wall on the horizontal promenade with parapet, g) landward storm wall with parapet, h) stilling wave basin (SWB) with parapet, under breaking wave conditions. The SWB is made up of a seaward storm wall (may be a double shifted rows) , a sloping promenade (basin) and a landward storm wall. The seaward storm wall is partially permeable to allow the evacuation of the water in the basin.

scholarly journals EXPECTED DISCHARGE OP IRREGULAR WAVE OVERTOPPING

1968 ◽  
Vol 1 (11) ◽  
pp. 54 ◽  
Author(s):  
Senri Tsuruta ◽  
Yoshimi Goda
Keyword(s):  
Vertical Wall ◽  
Laboratory Data ◽  
Irregular Waves ◽  
Linear Summation ◽  
Wave Overtopping ◽  
Irregular Wave ◽  
Concrete Blocks ◽  
Vertical Walls ◽  
Expected Values ◽  
Sea Wall

An experiment was carried out on the overtopping of mechanically generated irregular waves over vertical walls. The experimental discharge was almost in agreement with the expected discharge which had been calculated with the wave height histogram and the data of regular wave overtopping based on the principle of linear summation. The expected values of overtopping discharge were calculated for various laboratory data, which had been represented in a unified form of non-dimensional quantities. The calculation has yielded two diagrams of expected overtopping discharge, one for the sea wall of vertical wall type and the othei for the sea wall covered with artificial concrete blocks.

scholarly journals Wave Overtopping over Coastal Structures with Oblique Wind and Swell Waves

2018 ◽  
Vol 6 (4) ◽  
pp. 149 ◽  
Author(s):  
Ivo van der Werf ◽  
Marcel van Gent
Keyword(s):  
Wind Waves ◽  
Wave Loading ◽  
Coastal Structures ◽  
Wave Overtopping ◽  
Oblique Wave ◽  
Coastal Structure ◽  
Test Programme ◽  
Specific Direction ◽  
Wave Basin

Most guidelines on wave overtopping over coastal structures are based on conditions with waves from one direction only. Here, wave basin tests with oblique wave attack are presented where waves from one direction are combined with waves from another direction. This is especially important for locations where wind waves approach a coastal structure under a specific direction while swell waves approach the coastal structure under another direction. The tested structure was a dike with a smooth and impermeable 1:4 slope. The test programme consisted of four types of wave loading: (1) Wind waves only: “sea” (approaching the structure with an angle of 45°), (2) Wind waves and swell waves from the same direction (45°), (3) Wind waves and swell waves, simultaneously from two different directions (45° and −45°, thus perpendicular to each other), and (4) Wind waves, simultaneously from two different directions (45° and −45°, thus perpendicular to each other). Existing guidelines on wave overtopping have been extended to predict wave overtopping discharges under the mentioned types of wave loading (oblique sea and swell conditions).

scholarly journals Wave Overtopping of Stepped Revetments

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1035 ◽  
Author(s):  
Nils B. Kerpen ◽  
Talia Schoonees ◽  
Torsten Schlurmann
Keyword(s):  
Scale Effects ◽  
Vertical Wall ◽  
Breaking Waves ◽  
Design Guidelines ◽  
Coastal Protection ◽  
Wave Overtopping ◽  
Wide Range ◽  
Run Up ◽  
The One ◽  
Parameter Ranges

Wave overtopping—i.e., excess of water over the crest of a coastal protection infrastructure due to wave run-up—of a smooth slope can be reduced by introducing slope roughness. A stepped revetment ideally constitutes a slope with uniform roughness and can reduce overtopping volumes of breaking waves up to 60% compared to a smooth slope. The effectiveness of the overtopping reduction decreases with increasing Iribarren number. However, to date a unique approach applicable for a wide range of boundary conditions is still missing. The present paper: (i) critically reviews and analyzes previous findings; (ii) contributes new results from extensive model tests addressing present knowledge gaps; and (iii) proposes a novel empirical formulation for robust prediction of wave overtopping of stepped revetments for breaking and non-breaking waves. The developed approach contrasts a critical assessment based on parameter ranges disclosed beforehand between a smooth slope on the one hand and a plain vertical wall on the other. The derived roughness reduction coefficient is developed and adjusted for a direct incorporation into the present design guidelines. Underlying uncertainties due to scatter of the results are addressed and quantified. Scale effects are highlighted.

scholarly journals Experimental Analysis of Wave Overtopping: A New Small Scale Laboratory Dataset for the Assessment of Uncertainty for Smooth Sloped and Vertical Coastal Structures

2019 ◽  
Vol 7 (7) ◽  
pp. 217 ◽  
Author(s):  
Hannah E Williams ◽  
Riccardo Briganti ◽  
Alessandro Romano ◽  
Nicholas Dodd
Keyword(s):  
Time Series ◽  
Physical Model ◽  
Numerical Models ◽  
Vertical Wall ◽  
Model Tests ◽  
Physical Models ◽  
Small Scale ◽  
Wave Condition ◽  
Wave Overtopping ◽  
Physical Model Tests

Most physical model tests carried out to quantify wave overtopping are conducted using a wave energy spectrum, which is then used to generate a free surface wave time series at the wave paddle. This method means that an infinite number of time series can be generated, but, due to the expense of running physical models, often only a single time series is considered. The aim of this work is to investigate the variation in the main overtopping measures when multiple wave times series generated from the same spectrum are used. Physical model tests in a flume measuring 15 m (length) by 0.23 m (width) with an operating depth up to 0.22 m were carried out using a stochastic approach on two types of structures (a smooth slope and a vertical wall), and a variety of wave conditions. Results show variation of overtopping discharge, computed by normalising the range of the discharges at a certain wave condition with the maximum value of the discharge in the range up to 10 % , when the same wave time series is used, but this range increases to 75 % when different time series are used. This variation is found to be of a similar magnitude to both the one found with similar experiments looking at the phenomena in numerical models, and that specified by the confidence bounds in empirical methods.

INTEGRATED DESIGN OF COASTAL PROTECTION WORKS FOR WENDUINE, BELGIUM

2012 ◽  
Vol 1 (33) ◽  
pp. 70 ◽  
Author(s):  
William Veale ◽  
Tomohiro Suzuki ◽  
Toon Verwaest ◽  
Koen Trouw ◽  
Tina Mertens
Keyword(s):  
Physical Model ◽  
Integrated Design ◽  
Low Frequency ◽  
Scale Model ◽  
Coastal Protection ◽  
New Wave ◽  
Wave Overtopping ◽  
Physical Model Tests ◽  
Physical Scale ◽  
Wave Basin

Wave overtopping tests were performed with a 1:25 physical scale model to determine the optimal geometry for design of new wave return walls at Wenduine, Belgium. Wave overtopping on the shallow foreshore at Wenduine was found to be dominated by low-frequency infragravity waves (f < 0.04 Hz at prototype scale). Mean wave overtopping discharge measured with the physical model compared well with the Van Gent (1999) empirical overtopping equations for shallow foreshores. Physical model tests confirmed that the stilling wave basin concept proposed by Geerearts, et al. (2006) and wave wall parapet concepts of van Doorslaer & De Rouck (2010) were effective at reducing the wave wall height required to meet the tolerable discharge overtopping standards.

scholarly journals A LABORATORY STUDY ON WAVE OVERTOPPING AT VERTICAL SEAWALLS WITH A SHINGLE FORESHORE

2018 ◽  
pp. 56 ◽  
Author(s):  
Md Salauddin ◽  
Jonathan Pearson
Keyword(s):  
Laboratory Study ◽  
Vertical Wall ◽  
Empirical Equations ◽  
Laboratory Measurements ◽  
Coastal Structures ◽  
Wave Overtopping ◽  
Empirical Prediction ◽  
Discharge Rates ◽  
Vertical Walls

The existing empirical prediction formulae to determine the wave overtopping characteristics are mainly based on the laboratory measurements with the use of an impermeable foreshore slope in front of the structure. Recently, EurOtop (2016), an updated version of previous overtopping manual has been published with revised empirical equations to estimate mean overtopping discharge rates at plain vertical walls with and without foreshore.As past studies were mostly carried out at vertical seawalls on a fixed impermeable bed, little knowledge is available on the performance of these processes at coastal structures on a permeable shingle beach. This study presents the baseline overtopping characteristics at a plain vertical wall on an impermeable 1:20 foreshore slope, and compares the results with existing empirical predictions (EurOtop, 2016). In this paper, only the results on mean overtopping discharge and mean sediment rate at vertical walls are reported.

Strategies to improve implementation of adaptive management practices for restoration in coastal Louisiana

Shore & Beach ◽  
2020 ◽  
pp. 83-91
Author(s):  
Tim Carruthers ◽  
Richard Raynie ◽  
Alyssa Dausman ◽  
Syed Khalil
Keyword(s):  
Adaptive Management ◽  
Management Practices ◽  
Numerical Models ◽  
The United States ◽  
State Agency ◽  
Coastal Protection ◽  
Coastal Restoration ◽  
Management Actions ◽  
Coastal Louisiana ◽  
Restoration Effort

Natural resources of coastal Louisiana support the economies of Louisiana and the whole of the United States. However, future conditions of coastal Louisiana are highly uncertain due to the dynamic processes of the Mississippi River delta, unpredictable storm events, subsidence, sea level rise, increasing temperatures, and extensive historic management actions that have altered natural coastal processes. To address these concerns, a centralized state agency was formed to coordinate coastal protection and restoration effort, the Coastal Protection and Restoration Authority (CPRA). This promoted knowledge centralization and supported informal adaptive management for restoration efforts, at that time mostly funded through the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA). Since the Deepwater Horizon (DWH) oil spill in 2010 and the subsequent settlement, the majority of restoration funding for the next 15 years will come through one of the DWH mechanisms; Natural Resource and Damage Assessment (NRDA), the RESTORE Council, or National Fish and Wildlife Foundation –Gulf Environmental Benefit Fund (NFWF-GEBF). This has greatly increased restoration effort and increased governance complexity associated with project funding, implementation, and reporting. As a result, there is enhanced impetus to formalize and unify adaptive management processes for coastal restoration in Louisiana. Through synthesis of input from local coastal managers, historical and current processes for project and programmatic implementation and adaptive management were summarized. Key gaps and needs to specifically increase implementation of adaptive management within the Louisiana coastal restoration community were identified and developed into eight tangible and specific recommendations. These were to streamline governance through increased coordination amongst implementing entities, develop a discoverable and practical lessons learned and decision database, coordinate ecosystem reporting, identify commonality of restoration goals, develop a common cross-agency adaptive management handbook for all personnel, improve communication (both in-reach and outreach), have a common repository and clearing house for numerical models used for restoration planning and assessment, and expand approaches for two-way stakeholder engagement throughout the restoration process. A common vision and maximizing synergies between entities can improve adaptive management implementation to maximize ecosystem and community benefits of restoration effort in coastal Louisiana. This work adds to current knowledge by providing specific strategies and recommendations, based upon extensive engagement with restoration practitioners from multiple state and federal agencies. Addressing these practitioner-identified gaps and needs will improve engagement in adaptive management in coastal Louisiana, a large geographic area with high restoration implementation within a complex governance framework.

Intercomparison of Mesoscale Model Simulations of the Daytime Valley Wind System

2011 ◽  
Vol 139 (5) ◽  
pp. 1389-1409 ◽  
Author(s):  
Juerg Schmidli ◽  
Brian Billings ◽  
Fotini K. Chow ◽  
Stephan F. J. de Wekker ◽  
James Doyle ◽  
...  
Keyword(s):  
Land Surface ◽  
Mesoscale Model ◽  
Numerical Models ◽  
Surface Wind ◽  
Sensible Heat Flux ◽  
Surface Wind Speed ◽  
Time Shift ◽  
Wind System ◽  
Valley Wind ◽  
The Mean

Three-dimensional simulations of the daytime thermally induced valley wind system for an idealized valley–plain configuration, obtained from nine nonhydrostatic mesoscale models, are compared with special emphasis on the evolution of the along-valley wind. The models use the same initial and lateral boundary conditions, and standard parameterizations for turbulence, radiation, and land surface processes. The evolution of the mean along-valley wind (averaged over the valley cross section) is similar for all models, except for a time shift between individual models of up to 2 h and slight differences in the speed of the evolution. The analysis suggests that these differences are primarily due to differences in the simulated surface energy balance such as the dependence of the sensible heat flux on surface wind speed. Additional sensitivity experiments indicate that the evolution of the mean along-valley flow is largely independent of the choice of the dynamical core and of the turbulence parameterization scheme. The latter does, however, have a significant influence on the vertical structure of the boundary layer and of the along-valley wind. Thus, this ideal case may be useful for testing and evaluation of mesoscale numerical models with respect to land surface–atmosphere interactions and turbulence parameterizations.

An experimental and numerical study of the resonant flow between a hull and a wall

2021 ◽  
Vol 930 ◽  
Author(s):  
I.A. Milne ◽  
O. Kimmoun ◽  
J.M.R. Graham ◽  
B. Molin
Keyword(s):  
Vortex Shedding ◽  
Particle Image ◽  
Numerical Study ◽  
Numerical Models ◽  
Vertical Wall ◽  
Liquefied Natural Gas ◽  
Narrow Gap ◽  
Image Velocimetry ◽  
High Degree ◽  
Wave Induced

The wave-induced resonant flow in a narrow gap between a stationary hull and a vertical wall is studied experimentally and numerically. Vortex shedding from the sharp bilge edge of the hull gives rise to a quadratically damped free surface response in the gap, where the damping coefficient is approximately independent of wave steepness and frequency. Particle image velocimetry and direct numerical simulations were used to characterise the shedding dynamics and explore the influence of discretisation in the measurements and computations. Secondary separation was identified as a particular feature which occurred at the hull bilge in these gap flows. This can result in the generation of a system with multiple vortical regions and asymmetries between the inflow and outflow. The shedding dynamics was found to exhibit a high degree of invariance to the amplitude in the gap and the spanwise position of the barge. The new measurements and the evaluation of numerical models of varying fidelity can assist in informing offshore operations such as the side by side offloading from floating liquefied natural gas facilities.

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