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  Subjects -> ENGINEERING (Total: 2269 journals)
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ENGINEERING (1201 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Full-text available via subscription   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 14)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 207)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 1)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 10)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 4)
Advanced Science     Open Access   (Followers: 4)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 4)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 6)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
Advances in Artificial Neural Systems     Open Access   (Followers: 3)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
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Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 9)
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Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 34)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 28)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access  
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 5)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 6)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 4)
Applied Sciences     Open Access   (Followers: 3)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 8)
Arkiv för Matematik     Hybrid Journal  
ASEE Prism     Full-text available via subscription   (Followers: 2)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 7)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 9)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 7)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
Batteries     Open Access   (Followers: 3)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 24)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 8)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 40)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 40)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 3)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 4)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 10)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 13)
City, Culture and Society     Hybrid Journal   (Followers: 20)
Clay Minerals     Full-text available via subscription   (Followers: 8)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 4)
Coastal Engineering     Hybrid Journal   (Followers: 10)
Coastal Engineering Journal     Hybrid Journal   (Followers: 3)
Coatings     Open Access   (Followers: 2)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 23)
Composite Interfaces     Hybrid Journal   (Followers: 5)
Composite Structures     Hybrid Journal   (Followers: 242)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 175)
Composites Part B : Engineering     Hybrid Journal   (Followers: 215)
Composites Science and Technology     Hybrid Journal   (Followers: 159)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
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Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 25)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 25)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 7)
Control Engineering Practice     Hybrid Journal   (Followers: 40)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 24)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)

        1 2 3 4 5 6 7 | Last

Journal Cover Coastal Engineering
  [SJR: 1.999]   [H-I: 74]   [10 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0378-3839
   Published by Elsevier Homepage  [3041 journals]
  • An experimental method to verify the failure of coastal structures by wave
           induced liquefaction of clayey soils
    • Abstract: Publication date: May 2017
      Source:Coastal Engineering, Volume 123
      Author(s): Valeria Chávez, Edgar Mendoza, Rodolfo Silva, Anahí Silva, Miguel A. Losada
      Although the dynamics involved in the liquefaction process are understood reasonably well, experimental work to reproduce the sinking of structures due to liquefaction, which is representative and repeatable, has so far not been recorded. In this work, three sets of experiments were performed in an attempt to fill the gaps in the knowledge by modelling a small scale reproduction of the failure. Firstly, an analysis of the role of the proportions of the initial fine sediment and water content is presented; secondly, a group of tests involving a vertical breakwater were performed, and thirdly, an experiment was carried out to reproduce the failure of a submerged structure on a clayey bed in the presence of waves. From these experiments, we were able to set thresholds for bed composition, below which soil liquefaction is likely to occur. It was determined that the potential to liquefy increases with the initial water content and that soils of 40% or more clay content may liquefy. This methodology has proven to be repeatable, allowing the reproduction of the sinking of coastal structures due to liquefaction of the underlying soil.

      PubDate: 2017-03-08T02:34:38Z
       
  • Modeling transient long waves propagating through a heterogeneous coastal
           forest of arbitrary shape
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): Che-Wei Chang, Philip L.-F. Liu, Chiang C. Mei, Maria Maza
      A model is proposed to study transient long waves propagating through coastal vegetation. The coastal forest is modeled by an array of rigid and vertically surface-piercing cylinders. The homogenization method, i.e. multi-scale perturbation theory, is applied to separate two contrasting physical length scales: the scale characterizing transient waves and the scale representing the diameter of and the spacing among cylinders. Fourier transform is employed so that the free surface elevation and velocity field are solved in the frequency domain. For each harmonic, the flow motion within a unit cell, consisting of one or more cylinders, is obtained by solving the micro-scale boundary-value problem, which is driven by the macro-scale (wavelength scale) pressure gradients. The cell-averaged equations governing the macro-scale wave amplitude spectrum are derived with the consideration of the effects of the cell problem solution. Similar to [1], the macro-scale wave amplitude spectrum is solved numerically with the boundary integral equation method, where a vegetated area is composed of multiple patches of arbitrary shape. Each forest patch can be divided into subzones according to different properties, such as planting pattern and vegetation size. Each subzone is considered as a homogeneous forest region with a constant bulk eddy viscosity determined by the empirical formula suggested in [13]. Once the solutions for wave amplitude spectrum are obtained, the free surface elevation can then be computed from the inverse Fourier transform. A computing program is developed based on the present numerical model. To check the present approach, we investigate several different forest configurations. However, we focus on incident waves with a soliton-like shape. We first re-examine the forest belt case. The numerical model is then checked by available theoretical results along with experimental measurements for two special forest configurations. For a single circular forest, the numerical results compare almost perfectly with the analytical solutions. The comparison with experimental data also shows very good agreements. The effects of different wave parameters on damping rate are discussed. The numerical model is further compared with the experiments for a forest region consisting of multiple circular patches. Good agreements are also observed between the simulated free surface elevations and the experimental measurements. The effectiveness of these two forest configurations on wave attenuation is discussed.

      PubDate: 2017-03-02T02:29:32Z
       
  • An event-based approach for extreme joint probabilities of waves and sea
           levels
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): Franck Mazas, Luc Hamm
      A methodology for determining extreme joint probabilities of two metocean variables, in particular wave height and sea level, is presented in the paper. This methodology focuses in particular on the sampling of the time series, which should be based on the notion of event: either the event generating the variables whose joint probabilities are wanted (such as a storm generating waves and surges) or the event that is a result of the combination of these variables (such as a beach erosion event generated by waves at high sea level). A classification is proposed for multivariate analyses in order to help the choice of the sampling method. The dependence between the variables is analysed using tools such as the chi-plot, of which an enhanced presentation is proposed, then is modelled by extreme-value copulas (Gumbel-Hougaard, Galambos and Hüsler-Reiss) estimated by Canonical Maximum Likelihood or by the upper tail dependence coefficient. Joint return periods are then computed. A comparison is made with a simulation from the JOIN-SEA software on a dataset of wave height and sea levels offshore Brest, France. Then the bivariate methodology is extended to a multivariate framework. The distribution of sea level is determined by an indirect approach (extrapolation of extreme surges then convolution with the astronomical tide) and the dependence is analysed between the wave height and the surge component only. A bidimensional convolution between the joint distribution of wave height and surge and the distribution of the astronomical tide yields the joint distribution of wave height and sea level. The application of this method to the dataset of Brest and its comparison with the bivariate approach are finally discussed.

      PubDate: 2017-02-22T18:43:15Z
       
  • Wave loadings acting on innovative rubble mound breakwater for overtopping
           wave energy conversion
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): Pasquale Contestabile, Claudio Iuppa, Enrico Di Lauro, Luca Cavallaro, Thomas Lykke Andersen, Diego Vicinanza
      The Overtopping BReakwater for Energy Conversion (OBREC) is an overtopping type wave energy converter, totally embedded into traditional rubble mound breakwaters. The device consists of a reinforced concrete front reservoir designed with the aim of capturing the wave overtopping in order to produce electricity. The energy is extracted through low head turbines, using the difference between the water levels in the reservoir and the sea water level. This paper investigates the nature and magnitude of wave loadings exerting on various parts of the structure. The results improve the overall knowledge on the device behavior, completing the highlights from the complementary test campaign carried out in the same wave flume in 2012 (Vicinanza et al., 2014). The formulas provided have been used to design the first OBREC prototype breakwater in operation since January 2016 at Naples Harbour (Italy).

      PubDate: 2017-02-22T18:43:15Z
       
  • A Boussinesq type extension of the GeoClaw model - a study of wave
           breaking phenomena applying dispersive long wave models
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): Jihwan Kim, Geir K. Pedersen, Finn Løvholt, Randall J. LeVeque
      The nonlinear shallow water model is widely used in the study of tsunami propagation, but an increasing number of studies are dedicated to the dispersion dynamics of tsunamis. If the wave dispersion becomes important, Boussinesq-type models are often used. In this work, a general purpose Boussinesq solver, BoussClaw, is introduced for modeling non-linear dispersive tsunami propagation, taking into account inundation. The BoussClaw model is an extension of the GeoClaw tsunami model. It employs a hybrid of finite volume and finite difference methods to solve Boussinesq equations from the literature, which are based on the depth-averaged velocity and include enhanced dispersion properties. On the other hand, in the selected formulation only some non-linearity is retained in the dispersion term. In order to validate BoussClaw, numerical results are compared to analytic solutions, solutions obtained by pre-existing models, and laboratory experiments. Even though the equations of BoussClaw are not fully nonlinear they perform far better than standard Boussinesq equations with only linear dispersion terms. Furthermore, the wave steepening and breaking are carefully scrutinized, and we demonstrate that the point of wave breaking may be wrongly identified in many of the commonly used Boussinesq models.

      PubDate: 2017-02-22T18:43:15Z
       
  • Numerical simulation of scour and backfilling processes around a circular
           pile in waves
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): C. Baykal, B.M. Sumer, D.R. Fuhrman, N.G. Jacobsen, J. Fredsøe
      This study continues the investigation of flow and scour around a vertical pile, reported by Roulund et al. (2005). Flow and scour/backfilling around a vertical pile exposed to waves are investigated by using a three-dimensional numerical model based on incompressible Reynolds averaged Navier–Stokes equations. The model incorporates (1) k-ω turbulence closure, (2) vortex shedding processes, (3) sediment transport (both bed and suspended load), as well as (4) bed morphology. The numerical simulations are carried out for a selected set of test conditions of the laboratory experiments of Sumer et al. (1997, 2013a), and the numerical results are compared with those of the latter experiments. The simulations are carried out for two kinds of beds: rigid bed, and sediment bed. The rigid-bed simulations indicate that the vortex shedding for waves around the pile occurs in a “one-cell” fashion with a uniform shedding frequency over the height of the cylinder, unlike the case for steady current where a two-cell structure prevails. The rigid-bed simulations further show that the horseshoe vortex flow also undergoes substantial changes in waves. The amplification of the bed shear stress around the pile (including the areas under the horseshoe vortex and the lee wake region) is obtained for various values of the Keulegan-Carpenter number, the principal parameter governing the flow around the pile in waves. The present model incorporated with the morphology component is applied to several scenarios of scour and backfilling around a pile exposed to waves. In the backfilling simulations, the initial scour hole is generated either by a steady current or by waves. The present simulations indicate that the scour and backfilling in waves are solely governed by the lee-wake flow, in agreement with observations. The numerical model has proven successful in predicting the backfilling of scour holes exposed to waves. The results of the numerical tests indicate that the equilibrium depth of scour holes is the same for both the scour and the backfilling for a given Keulegan-Carpenter number, in full agreement with observations.

      PubDate: 2017-02-22T18:43:15Z
       
  • Efficient and robust wave overtopping estimation for impermeable coastal
           structures in shallow foreshores using SWASH
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): Tomohiro Suzuki, Corrado Altomare, William Veale, Toon Verwaest, Koen Trouw, Peter Troch, Marcel Zijlema
      Estimation of wave overtopping over the crest of coastal structures is crucial to design effective and cost efficient countermeasures against storms. Semi-empirical formulas are often used for wave overtopping assessment, but they are not always applicable for complex structures which exist in reality (e.g. a storm wall on a dike in a shallow or very shallow foreshore). Detailed numerical models such as Eulerian and Lagrangian RANS models have potential to simulate overtopping of complex coastal structures with good accuracy. However such models require significant computational resources. The use of such models is often not feasible for the design of coastal structures, which often requires multiple iterations and model runs over a reasonably long period of time (e.g. wave trains with 1000 individual waves). In this paper we investigated the applicability of the simplified depth integrated wave transformation model SWASH for wave overtopping estimation of impermeable coastal structures in shallow foreshores. The validation results demonstrate the capability of SWASH to predict mean wave overtopping discharge with good accuracy compared to results from four different overtopping experimental campaigns (comprising 124 individual cases). The overall performance of SWASH to estimate mean wave overtopping discharge is as accurate as those obtained by semi-empirical equations in literature. However, in order to obtain accurate mean wave overtopping discharge with the SWASH model, the incident wave properties at the toe of the dike need to be accurately reproduced. For cases where this is not possible, a correction method is proposed in this paper. Detailed validation of the instantaneous wave overtopping also shows a good agreement with physical model data. In one example, a single, intensive overtopping event was not well resolved by the SWASH model and the instantaneous wave overtopping was under-predicted. However, this did not contribute significantly to the mean wave overtopping discharge. An additional advantage of the SWASH model is that specific coastal structure geometries can be modelled in SWASH if they are not covered by semi-empirical equations. Even in a case with rapidly varied flow (e.g. vertical wall on a dike) the model shows sufficient robustness. In this paper the details on the SWASH model configuration and post processing methods are outlined to enable the reader to reproduce reliable wave overtopping estimation over impermeable coastal structures in shallow foreshores.

      PubDate: 2017-02-22T18:43:15Z
       
  • Modelling of long waves generated by bottom-tilting wave maker
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): Heng Lu, Yong Sung Park, Yong-Sik Cho
      In order to generate very long waves in laboratory, a bottom-tilting wave maker is designed and used at the University of Dundee. This new type of wave maker can produce waves longer than solitary waves in terms of the effective wavelength, which provides better long wave model. Nonlinear and dispersive numerical models are built for modelling the wave tank. A shock-capturing finite volume scheme with high-order reconstruction method is used to solve the governing equations. By comparing to the experimental measurements, the numerical models are verified and able to approximate the resulting waves in the wave tank.

      PubDate: 2017-02-15T17:59:22Z
       
  • Comparison of inundation depth and momentum flux based fragilities for
           probabilistic tsunami damage assessment and uncertainty analysis
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): Hyoungsu Park, Daniel T. Cox, Andre R. Barbosa
      Annual exceedance probabilities of the maximum tsunami inundation depth, h Max , and momentum flux, M Max , conditional on a full-rupture event of the Cascadia Subduction Zone (CSZ) were used to estimate the probability of building damage using a fragility analysis at Seaside, Oregon. Tax lot data, Google Street View, and field reconnaissance surveys were used to classify the buildings in Seaside and to correlate building typologies with existing fragility curves according to the construction material, number of stories, and building seismic design level based on the date of construction. A fragility analysis was used to estimate the damage probability of buildings for 500-, 1000-, and 2500-year exceedance probabilities conditioned on a full-rupture CSZ event. Finally, the sensitivity of building damage was estimated for both the aleatory and epistemic uncertainties involved in the process of damage estimation. Probable damage estimates from the fragility curves based on h Max and on M Max both generally show higher damage probability for structures that are wooden and closer to the shoreline than those that are reinforced concrete (RC) and further landward of the shoreline. However, a relatively high and somewhat unrealistic damage probability was found at the river and creek region from the fragility curve analysis using h Max . Within 500m from the shoreline, wood structure damage shows significant sensitivity to the aleatory uncertainty of the tsunami generation from the CSZ event. On the other hand, RC structure damage showed equal sensitivity to the aleatory uncertainty of the tsunami generation as well as the epistemic uncertainties due to the numerical modeling of the tsunami inundation (friction), the building classification (material and date of construction), and the type of fragility curves (depth or momentum flux type curves). Further from the shoreline, the wood structures showed similar aleatory and epistemic uncertainties, qualitatively similar to the RC structure sensitivity closer to the shoreline.

      PubDate: 2017-02-15T17:59:22Z
       
  • The influence of swash-based reflection on surf zone hydrodynamics: a
           wave-by-wave approach
    • Abstract: Publication date: April 2017
      Source:Coastal Engineering, Volume 122
      Author(s): Kévin Martins, Chris E. Blenkinsopp, Rafael Almar, Jun Zang
      A detailed understanding of the behaviour of waves in the nearshore is essential for coastal engineers as these waves cause beach erosion, coastal flooding and damage to coastal structures. Significantly, the influence of reflected waves is often neglected in surf zone studies, although they are known to influence wave properties and circulation in the nearshore. In this paper, a phase-resolving model is rigorously applied to model conditions from the prototype-scale BARDEXII experiment in order to examine and assess the influence of swash-based reflection on surf zone hydrodynamics at both the individual wave and time-averaged timescales. Surface elevation is separated into incoming and outgoing signals using the Radon Transform and a crest tracking algorithm is used to extract incident and reflected wave properties. It is found that on steep beaches ( tan β > 1 : 9 ) the swash-based reflection - the reflection generated in the swash during the backwash - contributes significantly to the intrawave variability of individual wave properties such as the wave height to water depth ratio γ, through the generation of quasi-nodes/antinodes system. For γ expressed with individual wave heights, variations up to 25% and 40% are obtained for the modelled regular and irregular wave tests, whereas it reaches 15% when it is based on the significant wave height. The outgoing wave field-induced hydrodynamics is also found to affect time-averaged parameters: undertow and horizontal velocity skewness. The undertow is mainly strengthened, particularly in the shoaling region where the outgoing component dominates over the contribution from the incoming wave field. Offshore of the bar, an onshore-directed flow streaming close to the bed is also generated under the outgoing wave field, and is suspected to help in stabilising the bar position. This, along with the influence of the outgoing wave field on the horizontal velocity skewness and the presence of quasi-standing waves, suggests a complex contribution of the hydrodynamics induced by swash-based reflection into sediment transport rates and nearshore bar generation/migration.

      PubDate: 2017-02-15T17:59:22Z
       
  • Wave load on submerged quarter-circular and semicircular breakwaters under
           irregular waves
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Xue-Lian Jiang, Qing-Ping Zou, Na Zhang
      Laboratory experiments were conducted to investigate the characteristics of wave loading on submerged circular-front breakwaters due to irregular waves. The wave force spectrum for a semicircular breakwater is similar to that for a quarter-circular breakwater. The dimensionless peak wave force for irregular waves is less than that for regular waves. The performance of our theoretical wave load model is improved significantly by incorporating the effect of wave transmission and flow separation. A RANS-VOF model was used to investigate the effect of local hydrodynamic disturbances by submerged breakwaters on the pressure distribution around the breakwater and total wave load. The numerical results reveal that wave-induced vortices at the structure have a substantial influence on the wave loading on the submerged quarter-circular breakwater but not on the semicircular breakwater. A parametric analysis is required to further improve the relationship between wave loads and the vortices.

      PubDate: 2017-02-04T13:38:51Z
       
  • High-resolution multi-scale modelling of coastal flooding due to tides,
           storm surges and rivers inflows. A Cork City example
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Agnieszka I. Olbert, Joanne Comer, Stephen Nash, Michael Hartnett
      This paper demonstrates the capability of a new state-of-the-art flood modelling system consisting of multiple nested models to simulate urban coastal flood inundation. A flood event in Cork City, Ireland which occurred in November 2009 is analysed in detail. The new flood modelling system comprises of two dynamically linked models: an ocean model (POM) of the northeast Atlantic (ca. 5km grid) and a coastal flood model, MSN_Flood, which resolves the hydrodynamics of Cork Harbour and its sub region at four spatial scales 90m, 30m, 6m and 2m through a cascade of four nested grids. Flood water propagation through Cork City floodplains is simulated by the 2m grid model. The POM-MSN_Flood modelling system, presented for the first time in this paper, was used to investigate the dynamics of coastal flooding resulting from a complex set of tides, storm surges, rivers inflows and the interactions between them. Unlike many flood models, the modelling system used in this research provides a full description of water levels and flow regimes, both in coastal waters and urban floodplains. Validation results clearly demonstrate that the model is capable of resolving hydrodynamics at scales commensurate with flow features including the large scale processes of the NE Atlantic Ocean and the fine resolution circulation of coastal waters. With regards to urban flooding, the model was found to accurately determine flood wave propagation patterns, flood wave heights, speeds and inundation extents. Ultimately, the model was used to investigate mechanisms of flooding resulting from multiple process drivers and to assess flood risk to human safety. Such an analysis facilitates better understating of the mechanics and dynamics of complex coastal urban flooding and would therefore be of interest in the field of coastal management.

      PubDate: 2017-02-04T13:38:51Z
       
  • Momentum transfer under laboratory wind waves
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): M. Olfateh, P. Ware, D.P. Callaghan, P. Nielsen, T.E. Baldock
      In this study, we explain contradictory previous observations of the contribution of coherent wave organised motion to the downward transfer of momentum through wave Reynolds stresses ( ρ u ˜ w ˜ ¯ ) below wind waves. The generation of non-zero u ˜ w ˜ ¯ is potentially significant because 1) the turbulent mixing is not then the only momentum transport mechanism under wind waves as was previously assumed, 2) this provides a wave-current energy exchange pathway that could explain inconsistencies in measured air- and water-side wind-wave energy transfer and 3) it can be a critical term in the wave-current coupling formulation under wind waves. However, such a mechanism for momentum transfer has generally been ignored, since contradictory observations were reported. Here, two new sets of wind-wave laboratory experiments are reported. For the first set, contradictory u ˜ w ˜ ¯ were observed, as in previous literature. Investigating the sources of such inconsistency, we examined spatial inhomogeneity due to wave reflection through a second set of experiments, by varying instrument location and additionally considering random waves. The results resolve the inconsistencies observed in the first set of experiments and previous measurements. In addition, we emphasise the contribution of secondary circulation cells in momentum transfer under wind waves.

      PubDate: 2017-01-28T13:09:12Z
       
  • Contributions to the wave-mean momentum balance in the surf zone
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Jebbe van der Werf, Jan Ribberink, Wouter Kranenburg, Kevin Neessen, Marien Boers
      Mean (wave-averaged) cross-shore flow in the surfzone has a strong vertical variation. Good understanding and prediction of this mean velocity profile is of crucial importance, as it determines the advective transport of constituents, such as sediment, and consequently the coastal morphological evolution. Most modeling systems for coastal hydrodynamics and morphodynamics do no resolve the wave motion, and wave-current coupling is a challenging topic. This paper investigates stresses and forces that control mean surfzone hydrodynamics based on detailed wave flume velocity measurements above a fixed sloping bed including two breaker bars. The data show that the vertical distribution of normal stress below the wave trough level is fairly uniform. At the same time, the data suggest that a significant part is concentrated between the wave trough and crest level. Furthermore, it is concluded that the horizontal radiation stress gradients and the vertical shear stress gradients can be of the same order of magnitude in the vicinity of the breaker bar. Although usually ignored in 3D mean flow modeling systems, the wave Reynolds stress makes an important contribution to the mean shear stress. The normal stress below the wave trough level could be reasonably well predicted using the classical [16] expression, accounting for the contribution between wave crest and trough. The model of [39] reproduces the main trends in the wave Reynolds stresses above the bottom boundary layer.

      PubDate: 2017-01-22T12:37:04Z
       
  • Analysis and classification of stepwise failure of monolithic breakwaters
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): H. Elsafti, H. Oumeraci
      Analysis, interpretation and classification of stepwise failure of monolithic breakwaters are presented. Through the stepwise failure mechanism, monolithic breakwaters develop incremental residual displacements with each wave load event. This mode of failure is associated with the highly complex processes involved in wave–structure–foundation interaction and may occur even under relatively moderate wave conditions. Based on the results of the analysis of a well validated CFD–CSD model system and large-scale physical model test data, a new concept, named load eccentricity concept, is proposed to classify the response of the foundation in four load eccentricity regimes. This concept is based on the relative eccentricity e / B , i.e. the ratio of eccentricity e of the vertical force resultant from the mid-point of the foundation–structure interface related to width B of this interface. In fact, the relative eccentricity carries all significant information related to the wave loads (horizontal and uplift forces) and to the properties of the structure (mass and geometry). Further, a new 3-DOF model, which can handle the system nonlinearity (e.g. soil plasticity), is developed for preliminary analysis. For the application of the model, only two parameters are needed: the relative load eccentricity and the relative soil density.

      PubDate: 2017-01-22T12:37:04Z
       
  • Experimental investigation of the hydroelastic and the structural response
           of a moored pontoon-type modular floating breakwater with flexible
           connectors
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Eva Loukogeorgaki, Elpida Niki Lentsiou, Murat Aksel, Oral Yagci
      In this paper, 3D experiments are conducted aiming at the combined investigation of the hydroelastic and the structural (connectors' internal forces) response of a pontoon-type modular Floating Breakwater (FB), consisting of flexibly connected, moored with chains modules, under the action of perpendicular and oblique regular waves. Regarding the FB's hydroelastic response (i.e. 3D displacements of the modules under the wave action), video recording of the horizontal and the vertical displacements of specific points on the FB relatively to some fixed points is implemented, and this response is determined through an appropriate image processing procedure. For assessing the FB's structural response, strain rosettes are utilized, enabling the evaluation of the connectors' forces through the corresponding strains' measurements. The effect of the incident wave characteristics (period, height, obliquity) on the FB's hydroelastic and structural response is analyzed. The correlation between the connectors' forces and the FB's hydroelastic response is extensively discussed. The FB's hydroelastic and structural response depends strongly upon the wave period, while the wave height and obliquity affect this response in the low frequency range. Strong dependency of the connectors' forces upon the existence or not of a FB's intense deformed shape is demonstrated.

      PubDate: 2017-01-22T12:37:04Z
       
  • The current generated by deep water regular waves
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): A.K. Bratland
      Second-order mean drift of wave particles can in deep water be calculated using potential theory, resulting in the well-known Stokes drift. Potential theory assumes an ideal, incompressible and irrotational flow, which according to Longuet-Higgins [8] is not permanent. In this document it is recommended, for rotational flow, to add a current term to Stokes wave equations. This is based on the argument that a change in wave number is due to the onset of a current.

      PubDate: 2017-01-14T11:55:02Z
       
  • Prediction of non-breaking wave induced scour depth at the trunk section
           of breakwaters using Genetic Programming and Artificial Neural Networks
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Ali Pourzangbar, Miguel A. Losada, Aniseh Saber, Lida Rasoul Ahari, Philippe Larroudé, Mostafa Vaezi, Maurizio Brocchini
      Scour may act as a threat to coastal structures stability and reduce their functionality. Thus, protection against scour can guarantee these structures’ intended performance, which can be achieved by the accurate prediction of the maximum scour depth. Since the hydrodynamics of scour is very complex, existing formulas cannot produce good predictions. Therefore, in this paper, Genetic Programming (GP) and Artificial Neural Networks (ANNs) have been used to predict the maximum scour depth at breakwaters due to non-breaking waves ( S max / H n b ). The models have been built using the relative water depth at the toe ( h t o e / L n b ), the Shields parameter ( θ ), the non-breaking wave steepness ( H n b / L n b ), and the reflection coefficient ( C r ), where in the case of irregular waves, H nb =H rms , T nb =T peak and L nb is the wavelength associated with the peak period (L nb =L p ). 95 experimental datasets gathered from published literature on small-scale experiments have been used to develop the GP and ANNs models. The results indicate that the developed models perform significantly better than the empirical formulas derived from the mentioned experiments. The GP model is to be preferred, because it performed marginally better than the ANNs model and also produced an accurate and physically-sound equation for the prediction of the maximum scour depth. Furthermore, the average percentage change (APC) of input parameters in the GP and ANNs models shows that the maximum scour depth dependence on the reflection coefficient is larger than that of other input parameters.

      PubDate: 2017-01-14T11:55:02Z
       
  • Laboratory experiments on beach change due to nearshore mound placement
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Ernest R. Smith, Michael C. Mohr, Shanon A. Chader
      Movable-bed large-scale laboratory experiments were conducted to examine the fate and quantify the benefits of nearshore placed dredged material. Two tests were performed on a beach classified as eroding [19] for mounds placed in the active zone described by Hands and Allison [12] at two depths. Mound sand was dyed to provide contrast and to differentiate it from the native sand beach. Beach surveys were performed intermittently during each experiment with a laser scanner. In addition to beach change elevations, the scanner provided RGB color components, which permitted tracking of the mound sand. The experiments showed that the mound sand dispersed rapidly and was transported mainly downdrift. Sand accumulation was observed on the beach onshore and adjacent to the mounds mainly due to wave sheltering of the mounds described as the longshore effect by [28]. There was little contribution to onshore accretion from cross-shore migration of the mounds. Beach response was similar to that of an offshore breakwater in which the mounds provided a wave shadow zone to the leeward beach. The results from the experiment will provide validation data for the numerical morphological model C2SHORE [15].

      PubDate: 2017-01-14T11:55:02Z
       
  • SPH numerical simulation of tsunami wave forces impinged on bridge
           superstructures
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Mohammad Sarfaraz, Ali Pak
      This paper addresses numerically-derived tsunami wave loads on bridge superstructures using smoothed particle hydrodynamics (SPH), which is a type of mesh-free methods. Although there exist some relationships for the case of impinged loads on bridges exerted by regular (sinusoidal) waves, for the case of solitary waves such as tsunamis, no relation has yet been proposed in the literature. This shortcoming is partly due to the lack of understanding the mechanism of wave action on the bridge superstructures. In this study, three water depths, three wave amplitudes and four submergence depths of the deck are considered for the process of numerical investigation of tsunami-induced loads on bridge superstructures. The bridge elevation is chosen such that its deck may become either completely emerged, partially submerged or completely submerged upon occurrence of the tsunami event. Comparison of the numerical results with the experiment recordings approves high level of accuracy of the SPH scheme. Based on the obtained results from the numerical modeling, the maximum applied horizontal and vertical forces, to the bridge superstructure are presented for each configuration of water depths, wave amplitudes, and deck elevations. In this way, the maximum clockwise/counterclockwise moments induced at the center of the structure are also determined. Simple non-dimensional equations are proposed for computing the tsunami-induced forces and moments to the bridge superstructures, which can be used for designing the bridge superstructures at the coastal areas.

      PubDate: 2017-01-14T11:55:02Z
       
  • Regional-scale probabilistic shoreline evolution modelling for flood-risk
           assessment
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Stuart Stripling, Michael Panzeri, Belen Blanco, Kate Rossington, Paul Sayers, Alistair Borthwick
      Rapid deterministic modelling of shoreline evolution at regional and coastal-scheme scale enables Monte-Carlo simulations by which long-term shoreline statistics can be estimated. This paper describes UnaLinea, a fast, accurate finite difference solver of the one-line sediment continuity equation. The model is verified for the evolution of an initially straight shoreline of a plane beach subject to regular breaking waves at constant angle of incidence in the presence of either a groyne or a continuous single-point feed of sediment. Grid convergence and stability tests are used to obtain accurate, stable results, with satisfactory computational efficiency. Influences of wave input filtering and event-based sediment loading are considered. The rapid deterministic model is applied to Monte-Carlo simulations of the evolution of the west coast of Calabria, Italy for different scenarios including increased sediment load from a river and selected beach nourishment. The potential role of probabilistic shoreline evolution in regional coastal flood-risk assessment is explored through application to an idealised stretch of the Holderness coastline, U.K., where flood depths and expected damage are estimated for a 1000 year return period event.

      PubDate: 2017-01-14T11:55:02Z
       
  • Numerical study of periodic long wave run-up on a rigid vegetation sloping
           beach
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Jun Tang, Yongming Shen, Derek M. Causon, Ling Qian, Clive G. Mingham
      Coastal vegetation can reduce long wave run-up on beaches and inland propagation distances and thus mitigate these hazards. This paper investigates periodic long wave run-up on coastal rigid vegetation sloping beaches via a numerical study. Rigid vegetation is approximated as rigid sticks, and the numerical model is based on an implementation of Morison's formulation [21] for rigid structures induced inertia and drag stresses in the nonlinear shallow water equations. The numerical model is solved via a finite volume method on a Cartesian cut cell mesh. The accuracy of the numerical model is validated by comparison with experimental results. The model is then applied to simulate various hypothetical cases of long periodic wave run-up on a sloping vegetated beach with different plant diameters and densities, and incident long waves with different periods. The sensitivity of long wave run-up to plant diameter, stem density and wave period is investigated by comparison of the numerical results for different vegetation characteristics and different wave periods. The numerical results show that rigid vegetation can effectively reduce long wave run-up and that wave run-up is decreased with increase of plant diameter and stem density. Moreover, the attenuation of long periodic wave run-up due to vegetation is sensitive to the variation of the incident wave period, and the attenuation of wave run-up is not increased or decreased monotonically with incident wave period.

      PubDate: 2017-01-14T11:55:02Z
       
  • Current and wave effects around windfarm monopile foundations
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Jon Miles, Tom Martin, Liam Goddard
      Laboratory measurements were undertaken to investigate wave and current velocities in the vicinity of a wind turbine monopile foundation, in order to inform environmental impact assessments and to quantify flow variability in the region of the power take off cable. Flow measurements were made up to 15.5 pile diameters (D) downstream of the pile. Measurements were also taken around the perimeter of the pile (~0.75 D from the pile centre) at the approximate representative height of the power cable. In current-only tests, the mean flow was reduced immediately downstream of the pile, but returned to within 5% of background levels by 8.3 D downstream of the pile centre in representative conditions. A new parameterisation of the velocity recovery is given. The turbulent eddy shedding frequency was well predicted by the Strouhal number. Turbulence peaked at 1.5 D from the pile centre, and the subsequent decay was parameterised. Velocity magnitudes at the side of the pile were up to 1.35 times greater than background flow rates, in line with potential flow theory. Velocities in the wake region were much less than predicted by potential flow theory, corresponding with increased turbulence. Tests with waves indicated that oscillatory velocities reduced immediately down-wave of the pile, but returned quickly to background levels (by 1.65 to 3.5 D of the pile centre). The general near-pile distribution of the orbital velocity maximum was well represented by potential flow theory. Orbital velocities were reduced immediately up-wave and down-wave of the pile. At the side of the pile in wind sea conditions, the velocity increased up to 1.66 times the background level. This increased to 1.85 times in swell conditions. For orthogonal currents and waves, a velocity parameter was calculated as the mean current plus wave orbital velocity, resolved. With the mean current direction as a reference, the maximum flow was observed at the side of the pile. At 0.75 D from the pile centre, the flow was enhanced by up to 1.2 times the no–pile case. Spectral peaks in the velocity were evident at both wave frequency and at the Strouhal frequency, immediately down current from the pile.

      PubDate: 2017-01-14T11:55:02Z
       
  • Effect of beach slope and grain-stabilization on coastal sediment
           transport: An attempt to overcome the erosion overestimation by XBeach
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Saber M. Elsayed, Hocine Oumeraci
      The reproduction of seventeen laboratory tests for dune erosion by the surf-beat mode of the two-dimensional horizontal (2DH) model XBeach for storm wave conditions showed that the model overestimates the erosion and thus the deposition volumes. This overestimation becomes particularly significant for very large overtopping rates on coastal barriers, which are commonly induced by extreme storm surges. In this paper, the recent model improvements to overcome this problem are first summarised. Moreover, two physical reasons for these overestimations are identified: (i) the wave nonlinearity effect on sediment transport, which is described in XBeach by a calibration factor for the time-averaged flow depending on the wave skewness and asymmetry and (ii) the considerable excess of the actual shear stress required to initiate the sediment particle motion as compared to that predicted by the common Shields curve. To improve the prediction capability of XBeach in terms of erosion and overwash volumes, two new improvements, related to the two aforementioned reasons for the overestimation, are introduced and implemented in the model. The improved XBeach model is then tested for dune erosion, for barrier breaching as well as for a barrier island erosion and overwash under an extreme storm surge event. The results showed a very good prediction capability of the improved model. Particularly, the second model improvement opens the way toward further model improvements to account for spatially varying soil resistance, which is crucial for reliable prediction of a barrier breaching.

      PubDate: 2017-01-14T11:55:02Z
       
  • Investigation of nonlinear wave-induced seabed response around mono-pile
           foundation
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Zaibin Lin, Dubravka Pokrajac, Yakun Guo, Dong-sheng Jeng, Tian Tang, Nick Rey, Jinhai Zheng, Jisheng Zhang
      Stability and safety of offshore wind turbines with mono-pile foundations, affected by nonlinear wave effect and dynamic seabed response, are the primary concerns in offshore foundation design. In order to address these problems, the effects of wave nonlinearity on dynamic seabed response in the vicinity of mono-pile foundation is investigated using an integrated model, developed using OpenFOAM, which incorporates both wave model (waves2Foam) and Biot's poro-elastic model. The present model was validated against several laboratory experiments and promising agreements were obtained. Special attention was paid to the systematic analysis of pore water pressure as well as the momentary liquefaction in the proximity of mono-pile induced by nonlinear wave effects. Various embedded depths of mono-pile relevant for practical engineering design were studied in order to attain the insights into nonlinear wave effect around and underneath the mono-pile foundation. By comparing time-series of water surface elevation, inline force, and wave-induced pore water pressure at the front, lateral, and lee side of mono-pile, the distinct nonlinear wave effect on pore water pressure was shown. Simulated results confirmed that the presence of mono-pile foundation in a porous seabed had evident blocking effect on the vertical and horizontal development of pore water pressure. Increasing embedded depth enhances the blockage of vertical pore pressure development and hence results in somewhat reduced momentary liquefaction depth of the soil around the mono-pile foundation.

      PubDate: 2017-01-14T11:55:02Z
       
  • Entrained air in bore-driven swash on an impermeable rough slope
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Han-Jing Dai, Gustaaf Adriaan Kikkert, Bo-Tao Chen, Dubravka Pokrajac
      The aim of the present investigation is to clarify the role and evaluate the importance of air entrainment in the swash zone by carrying out a set of detailed laboratory experiments. Experiments involved generating a single, highly repeatable, large-scale, bore-driven swash event on a sand-rough impermeable beach with slope 1:10. Measurements that yield the characteristics of the entrained air, including the void fractions, bubble size and bed-parallel bubble velocity, and the hydrodynamics are obtained at five cross-shore locations in the swash zone using an optical probe and a combined PIV/LIF system. The results show that two distinct bubble clouds enter the swash zone, the first is the result of local entrainment at the wave tip and the second are the remaining bubbles of the air that is entrained at the second plunge point of wave breaking before the wave starts climbing the beach. The void fractions are up to 0.20 and bubble size up to 20mm which are similar to air entrainment after wave breaking in the surf zone and deep water. Local entrainment of air continues in the swash zone, but void fractions decrease rapidly with distance up the slope and no air is present after flow reversal. Energy dissipation in the swash zone attributable to entrained air is at least of order 1% of the total energy dissipation. This is smaller than in the surf zone or deep water because of the smaller volume of entrained air and the greater total energy dissipation in the swash zone.

      PubDate: 2017-01-06T12:50:00Z
       
  • Optimisation of focused wave group runup on a plane beach
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): C.N. Whittaker, C.J. Fitzgerald, A.C. Raby, P.H. Taylor, J. Orszaghova, A.G.L. Borthwick
      Insight is provided into focused wave group runup on a plane beach by means of laboratory wave flume experiments and numerical simulations. A focused wave group is presented as an alternative to an empirical description of the wave conditions leading to extreme runup. Second-order correction to the laboratory wavemaker generation signal is observed to remove about 60% of the sub-harmonic error wave that would otherwise contaminate coastal response experiments. Laboratory measurements of the wave runup time history are obtained using inclined resistance-type wires and copper strips attached to the beach surface. The numerical wave runup model is based on hybrid Boussinesq-Nonlinear Shallow Water equations, empirical parameters for wave breaking and bed friction, and a wetting and drying algorithm. After calibration against experimental runup data, the numerical model reproduces satisfactorily the propagation, shoaling and runup of focused wave groups over the entire length of the wave flume. Results from a comprehensive parametric study show that both measured and predicted maximum runup elevations exhibit strong dependence on the linear focus amplitude of the wave group (linked to its probability of occurrence), the focus location, and the phase of the wave group at focus. The results also demonstrate that extreme runup events owing to focused wave incidence cannot be characterised using spectral parameters alone. The optimal band of focus locations shifts onshore as linear focus amplitude of the incident wave group increases. Optimisation of phase and focus location leads to a maximum runup elevation at each linear amplitude, and, when generated using second-order corrected paddle signals, the maximum runup appears to approach saturation at very large focused wave amplitudes. This study therefore moves beyond simple wave focusing, and presents a focused wave group as a tool for investigating the relationship between extremes within an incident wave field and extreme wave runup.

      PubDate: 2017-01-06T12:50:00Z
       
  • Measurements of suspended sediment transport and turbulent coherent
           structures induced by breaking waves using two-phase volumetric
           three-component velocimetry
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Paul D. LeClaire, Francis C.K. Ting
      Sediment suspension and transport under plunging regular waves was investigated in a laboratory surf zone using the volumetric three-component velocimetry technique. The two-phase flow measurements captured the motions of sediment particles simultaneously with the three-component, three-dimensional velocity fields of turbulent coherent structures (large eddies) induced by plunging breakers. Sediment particles were separated from fluid tracers based on a combination of particle spot size and brightness in the two-phase flow images. The interactions between the large eddies and bottom sediment were investigated in the outer surf zone. The measured data showed that breaker vortices impinging on the bottom was the primary mechanism that lifted sediment particles into suspension. High suspended sediment concentrations were found in the wall-jet region where the impinging flow was deflected outward and upward. Sediment particles were also trapped by counter-rotating vortices behind the down flow. Suspended sediment concentrations were significantly lower in the impingement zone where the fluid velocities were downward, even though the turbulent kinetic energy in the down flow was very high. Suspended sediment concentration was well correlated with vertical velocity and apparent shear stresses in the deflected flow, and with vorticity magnitude in the counter-rotating vortices. A linear relationship was found between net sediment flux and net turbulent kinetic energy flux over one wave cycle. It was found that a strong deflected flow in front of the impingement zone enhanced onshore sediment transport compared to a more symmetrical flow pattern, while counter-rotating vortices kept sediment particles in suspension for transport offshore after flow reversal. Onshore sediment transport was observed in less than 20% of the breaking waves. In most wave cycles, net sediment flux was directed offshore due to advection by predominantly offshore flow velocities.

      PubDate: 2017-01-06T12:50:00Z
       
  • Improving the parameterization of wave nonlinearities – The importance
           of wave steepness, spectral bandwidth and beach slope
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): M.V.L. Rocha, H. Michallet, P.A. Silva
      Wave-velocity nonlinearities are among the main drivers of sediment transport. For practical engineering purposes, they can be described by simple parameterizations that allow their easier inclusion in nearshore morphodynamic models. Most existing parameterizations propose the estimation of velocity nonlinearities only from local wave parameters (such as the Ursell number). Herein, it is demonstrated that this provides inaccurate estimations of the wave nonlinearities. Furthermore, the effect of offshore wave steepness, offshore spectral bandwidth and beach slope on the velocity nonlinearities is shown to be sufficiently important to merit its inclusion in the existing parameterizations. Ruessink et al. (2012) [28] parameterization is modified in order to include both offshore spectral bandwidth and a new parameter, NP 0, which takes into account the beach slope and the squared offshore wave steepness. The new parameterization results in a reduction of the wave-nonlinearities estimation error of more than 50%, particularly for the maximum values of nonlinearity (near breaking) that contribute the most for sediment transport.

      PubDate: 2017-01-06T12:50:00Z
       
  • RANS-based simulation of wave-induced sheet-flow transport of graded
           sediments
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Ugur Caliskan, David R. Fuhrman
      A one-dimensional vertical (1DV) turbulence-closure flow model, coupled with sediment transport capabilities, is extended to incorporate graded sediment mixtures. The hydrodynamic model solves the horizontal component of the incompressible Reynolds-averaged Navier–Stokes (RANS) equations coupled with k–ω turbulence closure. The sediment transport description includes both bed and suspended load descriptions. So-called high-concentration effects (turbulence damping and hindered settling velocities) are likewise included. The sediment transport model treats the bed and suspended load individually for each grain fraction, including effects associated with increased exposure of larger particles within a mixture. The suspended sediment transport model also makes use of modified reference concentration approach, wherein reference concentrations computed individually for each fraction are translated to a common level, conveniently enabling use of a single computational grid for the simulation of suspended sediments. Parametric study shows that these two effects combine to help alleviate an otherwise systematic tendency towards over- (under-) predicted transport rates for fine (coarse) sand fractions. The sediment transport model is validated against sheet-flow experimental oscillatory tunnel measurements beneath velocity-skewed wave signals, and demonstrates similar accuracy (transport rates generally within a factor of two) for both graded and uniform sands. The model is likewise validated against an extensive data set involving sheet-flow transport beneath acceleration-skewed wave signals (limited to uniform sands). It is then utilized to study potential effects of gradation on the net transport beneath such flows. The simulations suggest that gradation effects can both increase, as well as decrease, the total transport rate, depending largely on the behavior of the fine sand fraction. The model is implemented within the Matlab environment, and is freely available upon request to the corresponding author.

      PubDate: 2017-01-06T12:50:00Z
       
  • Modeling the long-term diffusion and feeding capability of a
           mega-nourishment
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Jaime Arriaga, Jantien Rutten, Francesca Ribas, Albert Falqués, Gerben Ruessink
      A morphodynamic model based on the wave-driven alongshore sediment transport, including cross-shore transport in a simplified way and neglecting tides, is presented and applied to the Zandmotor mega-nourishment on the Dutch Delfland coast. The model is calibrated with the bathymetric data surveyed from January 2012 to March 2013 using measured offshore wave forcing. The calibrated model reproduces accurately the surveyed evolution of the shoreline and depth contours until March 2015. According to the long-term modeling using different wave climate scenarios based on historical data, for the next 30-yr period, the Zandmotor will display diffusive behavior, asymmetric feeding to the adjacent beaches, and slow migration to the NE. Specifically, the Zandmotor amplitude will have decayed from 960m to about 350m with a scatter of only about 40m associated to climate variability. The modeled coastline diffusivity during the 3-yr period is 0.0021m2/s, close to the observed value of 0.0022m2/s. In contrast, the coefficient of the classical one-line diffusion equation is 0.0052m2/s. Thus, the lifetime prediction, here defined as the time needed to reduce the initial amplitude by a factor 5, would be 90yr instead of the classical diffusivity prediction of 35yr. The resulting asymmetric feeding to adjacent beaches produces 100m seaward shift at the NE section and 80m seaward shift at the SW section. Looking at the variability associated to the different wave climates, the migration rate and the slight shape asymmetry correlate with the wave power asymmetry (W vs N waves) while the coastline diffusivity correlates with the proportion of high-angle waves, suggesting that the Dutch coast is near the high-angle wave instability threshold.

      PubDate: 2016-12-28T03:20:01Z
       
  • EOF analysis of shoreline and beach slope variability at a feeder beach
           constructed within a groin field at Long Branch, New Jersey
    • Abstract: Publication date: March 2017
      Source:Coastal Engineering, Volume 121
      Author(s): Laura Lemke, Jon K. Miller
      The morphologic evolution of a beach nourishment project constructed in Long Branch, New Jersey, USA is investigated using the method of empirical orthogonal functions (EOF). Most applications of EOFs on beach fill projects have focused on traditional linear fills on relatively long, straight, uninterrupted coastlines. The Long Branch project was unique in that it was designed as a feeder beach and was constructed within a groin field. The method of EOF analysis is applied to help identify patterns representing distinct physical processes in data sets of shoreline position and shoreline slope at the site. The first three modes, determined from the shoreline position data set, explain more than 90% of the variation from the mean shoreline. The first and third modes represent variations of the fill's spreading as material moved to the north in the direction of the net littoral drift. Several shore-perpendicular structures interrupt the longshore transport and regulate the spreading. One of these structures is a large outfall pipe that was identified during the beach profile surveys to have a dominant influence over the shoreline evolution. The second mode identified in the shoreline data set is related to seasonal or storm impacts, and represents the transition between a reflective summer condition and a dissipative winter state. Several of the modes derived from the beach slope data set, represent processes similar to those identified in the shoreline data set. The first mode explains 43.1% of the variation in the beach slope data, and represents the seasonal transition between reflective and dissipative beach states. The second mode represents the equilibration of slopes within the beach fill and the initial spreading of the fill. Derivatives of the temporal coefficients of both the shoreline and beach slope data sets are consistent with a reduction in the rate of changes as equilibrium is approached, and an acceleration of changes during storms.

      PubDate: 2016-12-28T03:20:01Z
       
  • Impacts on a storm wall caused by non-breaking waves overtopping a smooth
           dike slope
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Koen Van Doorslaer, Alessandro Romano, Julien De Rouck, Andreas Kortenhaus
      Will coastal towns survive the rising pressure, or better, the rising sea level in future decades? Waves overtop dikes, and the overtopping flow on the crest of the dike can cause damage. Wave impacts from these overtopping flows already became of interest in coastal engineering the past few years, but very little literature and almost no design formulae are available yet for irregular waves. This paper gives such design formulae for practical use. Experimental modeling at three different scales (small, middle and large scale) has been carried out to measure such impacts. The tested geometry was a smooth sloping dike (only non-breaking waves) with a promenade at crest level and a storm wall at the end of this promenade. The outcome of this paper are three methodologies to a) calculate wave impact forces on such a storm wall as a function of the hydraulic parameters; b) determine the (Weibull) distribution of all impacts in one test, with the shape and scale parameters also linked to the hydraulic parameters; and c) to provide an indirect approach to calculate the impact forces on the storm wall. In this last approach, the (distribution of the) individual overtopping waves are linked to the (distribution of the) overtopping flow parameters, which are then linked to the (distribution of the) impact forces. Finally, the empirical formulae from the aforementioned three methodologies are compared; analogies and differences are discussed, and guidance is provided to design storm walls against post overtopping impact forces. Results show that forces from waves overtopping the dikes are in the order of 20 to 40kN/m prototype scale in the dimensionless freeboard (Rc/Hm0) range of 1 to 2. This is (much) lower compared to impact forces on vertical walls as calculated by the Shore Protection Manual.

      PubDate: 2016-12-20T15:53:27Z
       
  • A laboratory investigation concerning the superharmonic free wave
           suppression in shallow and intermediate water conditions
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): David Aknin, Johannes Spinneken
      This paper concerns laboratory wavemaking in shallow and intermediate water conditions. A comparison is made between two wave generation techniques, a first based on controlling the wavemaker displacement, and a second based on controlling the wavemaker force. Nonlinear wave generation in position control is well understood, and many laboratories rely on established second-order or Stream-function inputs. In deep water, using flap-type wavemakers, a force-control approach based on a linear demand signal was recently shown to offer benefits in terms of wave quality. The shallow water operation of such force-control strategies is less certain, which motivates the present study. To investigate the influence of the water depth on this type of control, a range of generation scenarios is considered, including small amplitude and large amplitude regular waves. Adopting both supporting calculations and experimental evidence, the work demonstrates that first-order force-based wave generation in shallow water suffers from similar limitations as first-order position control. This principally concerns the contamination of the testing area due to unwanted free waves, where the present focus is placed on the superharmonic range. The main advance of the work lies in the solutions it offers to overcome this free wave contamination. A number of nonlinear wave solutions upon which force-based generation can be based are discussed, and a suitable methodology is proposed and validated for each case. The developed methodology allows for high quality wave generation, whilst maintaining the benefit of active wave absorption. The work is timely in the sense that is responds to two recent developments. First, the majority of wavemaking facilities commissioned over the past two decades are computer controlled, and active absorption has become commonplace. The work presented offers solutions highly relevant to such installations. Second, developments particularly in offshore wind, have seen many new structures placed in relatively shallow-water depth. It is essential that the model testing of such structures adequately accounts for the issues and solutions presented herein.

      PubDate: 2016-12-20T15:53:27Z
       
  • Application of wave runup and wave rundown formulae based on long-term
           variation of wave conditions
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Dag Myrhaug, Bernt J. Leira
      The purpose of this note is to demonstrate that it is possible to use the proposed formulae in Blenkinsopp et al. [1] to estimate runup and rundown based on long-term variation of wave conditions by using the Myrhaug and Fouques [5] joint distribution of significant wave height and Iribarren number for a sea state. Examples of application are given for typical field conditions including a procedure of determining the 100-years return period values for the runup and rundown and the corresponding values of significant wave height and Iribarren number.

      PubDate: 2016-12-14T14:07:35Z
       
  • Observations and 3D hydrodynamics-based modeling of decadal-scale
           shoreline change along the Outer Banks, North Carolina
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): I. Safak, J.H. List, J.C. Warner, N. Kumar
      Long-term decadal-scale shoreline change is an important parameter for quantifying the stability of coastal systems. The decadal-scale coastal change is controlled by processes that occur on short time scales (such as storms) and long-term processes (such as prevailing waves). The ability to predict decadal-scale shoreline change is not well established and the fundamental physical processes controlling this change are not well understood. Here we investigate the processes that create large-scale long-term shoreline change along the Outer Banks of North Carolina, an uninterrupted 60km stretch of coastline, using both observations and a numerical modeling approach. Shoreline positions for a 24-yr period were derived from aerial photographs of the Outer Banks. Analysis of the shoreline position data showed that, although variable, the shoreline eroded an average of 1.5m/yr throughout this period. The modeling approach uses a three-dimensional hydrodynamics-based numerical model coupled to a spectral wave model and simulates the full 24-yr time period on a spatial grid running on a short (second scale) time-step to compute the sediment transport patterns. The observations and the model results show similar magnitudes (O(105 m3/yr)) and patterns of alongshore sediment fluxes. Both the observed and the modeled alongshore sediment transport rates have more rapid changes at the north of our section due to continuously curving coastline, and possible effects of alongshore variations in shelf bathymetry. The southern section with a relatively uniform orientation, on the other hand, has less rapid transport rate changes. Alongshore gradients of the modeled sediment fluxes are translated into shoreline change rates that have agreement in some locations but vary in others. Differences between observations and model results are potentially influenced by geologic framework processes not included in the model. Both the observations and the model results show higher rates of erosion (∼−1m/yr) averaged over the northern half of the section as compared to the southern half where the observed and modeled averaged net shoreline changes are smaller (<0.1m/yr). The model indicates accretion in some shallow embayments, whereas observations indicate erosion in these locations. Further analysis identifies that the magnitude of net alongshore sediment transport is strongly dominated by events associated with high wave energy. However, both big- and small- wave events cause shoreline change of the same order of magnitude because it is the gradients in transport, not the magnitude, that are controlling shoreline change. Results also indicate that alongshore momentum is not a simple balance between wave breaking and bottom stress, but also includes processes of horizontal vortex force, horizontal advection and pressure gradient that contribute to long-term alongshore sediment transport. As a comparison to a more simple approach, an empirical formulation for alongshore sediment transport is used. The empirical estimates capture the effect of the breaking term in the hydrodynamics-based model, however, other processes that are accounted for in the hydrodynamics-based model improve the agreement with the observed alongshore sediment transport.

      PubDate: 2016-12-14T14:07:35Z
       
  • SedFoam: A multi-dimensional Eulerian two-phase model for sediment
           transport and its application to momentary bed failure
    • Abstract: Publication date: January 2017
      Source:Coastal Engineering, Volume 119
      Author(s): Zhen Cheng, Tian-Jian Hsu, Joseph Calantoni
      A multi-dimensional Eulerian two-phase model for sediment transport, called SedFoam, is presented. The model was developed under the open-source framework via the CFD toolbox OpenFOAM. With closures of particle stresses and fluid-particle interactions, the model is able to resolve processes in the concentrated region of sediment transport and hence does not require conventional bedload/suspended load assumptions. A modified k − ϵ closure was adopted for the carrier flow turbulence. The model was validated for Reynolds-averaged steady and oscillatory sheet flows and verified with empirical formulae for scour downstream of an apron. The model was used to study momentary bed failure (or plug flow) under sheet flow conditions. Model results revealed the existence of instabilities of the near-bed transport layer when momentary bed failure criteria was exceeded. These instabilities evolved into 5–10cm billows and were responsible for the large transport rate. The instabilities were associated with a large erosion depth, which was triggered by the combination of large bed shear stresses and large horizontal pressure gradients. Further numerical experiments confirmed the conjecture by previous studies that a criterion for onset of momentary bed failure in oscillatory sheet flow was a function of both the Shields parameter and Sleath parameter.

      PubDate: 2016-12-14T14:07:35Z
       
  • Numerical modelling of the erosion and deposition of sand inside a filter
           layer
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Niels G. Jacobsen, Marcel R.A. van Gent, Jørgen Fredsøe
      This paper treats the numerical modelling of the behaviour of a sand core covered by rocks and exposed to waves. The associated displacement of the rock is also studied. A design that allows for erosion and deposition of the sand core beneath a rock layer in a coastal structure requires an accurate prediction method to assure that the amount of erosion remains within acceptable limits. This work presents a numerical model that is capable of describing the erosion and deposition patterns inside of an open filter of rock on top of sand. The hydraulic loading is that of incident irregular waves and the open filters are surface piercing. Due to the few experimental data sets on sediment transport inside of rock layers, a sediment transport formulation has been proposed based on a matching between the numerical model and experimental data on the profile deformation inside an open filter. The rock layer on top of a sand core introduces a correction term in the Exner equation (the continuity equation for sediment and change in bed level). The correction term originates from the fact that the sand can only be deposited in the pores of the filter material. The numerical model is validated against additional data sets on the erosion and deposition patterns inside of an open filter. A few cases are defined to study the effect of the sinking of the filter into the erosion hole. The numerical model is also applied to several application cases. The response of the core material (sand) to changes in the wave period and wave height is considered. The effect of different layouts of the filter is studied in order to investigate the effect of different filter profiles on the resulting erosion. Finally, it is studied how much the design of a hydraulically closed filter can be relaxed to obtain a reduction in the design requirements of the filter thickness, while the deformation to the sand core remains acceptably small.

      PubDate: 2016-12-07T09:28:04Z
       
  • Numerical modeling of the morphodynamic response of a low-lying barrier
           island beach and foredune system inundated during Hurricane Ike using
           XBeach and CSHORE
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Craig Harter, Jens Figlus
      Follet's Island (FI) is a sediment-starved barrier island located on the Upper Texas Coast; a stretch of coastline along the Gulf of Mexico that experiences on average four hurricanes and four tropical storms per decade. During Hurricane Ike, water levels and wave heights at FI exceeded the 100-year and 40-year return values, respectively, leading to significant overtopping and morphology changes of this low-lying barrier island. The physical processes governing the real-time morphodynamic response of the beach and dune system during 96h of hurricane impact were modeled using XBeach (2D) and CSHORE (1D). Hydrodynamic boundary conditions were obtained from ADCIRC/SWAN model runs validated with measured buoy and wave gauge data while LiDAR surveys provided pre- and post-storm measured topography. XBeach displayed a decent model skill of 0.34 and provided numerical outputs of the entire 2D domain such as topography, suspended sediment load and bed load which was very useful in visualizing erosion and deposition patterns. CSHORE also displayed a decent model skill of 0.33 and was able to accurately predict the post-storm beach slope and shoreline, but was less effective at simulating the foredune morphology. Modeling results show that the complete morphodynamic response of FI to Hurricane Ike was governed by a sequence of impact regimes, including swash, collision, overwash, inundation, and storm surge ebb.

      PubDate: 2016-12-07T09:28:04Z
       
  • Storm overwash of a gravel barrier: Field measurements and XBeach-G
           modelling
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Luis Pedro Almeida, Gerd Masselink, Robert McCall, Paul Russell
      Gravel barriers provide a natural form of coastal protection and flood defence for many sites around the UK and worldwide. Predicting their vulnerability to different storm impact regimes that cause overtopping and overwash is crucial as these processes can lead to hazardous consequences such as inundation of the back of the barrier or breaching. This paper presents the first field measurements of storm overwash events on a gravel beach (Loe Bar, Cornwall, England). High frequency in-situ observations (2Hz) were performed using a 2D laser-scanner and allowed a complete characterization of the overwash flows (velocity and depth) and morphological response along a cross-shore section of the barrier. These novel measurements are used to validate the numerical model XBeach-G, to forecast overwash discharge. Several simulations were performed with XBeach-G to investigate the thresholds for the different storm impact regimes, given a variety of water levels and wave heights. Wave period and wave spectral shape are found to significantly affect these thresholds. While short period waves dissipate most of their energy by breaking before reaching the swash zone and produce short runup excursions, long period waves due to their low steepness arrive at the swash zone unbroken with enhanced heights (due to shoaling) thus promoting large runup excursions. When the offshore wave spectrum has a bimodal shape, wave transformation in shallow water causes the long period peak to dominate the swash giving large runup excursions. Long period waves or strongly bimodal waves result in enhanced runup thereby reducing the thresholds for barrier overtopping or overwashing.

      PubDate: 2016-11-30T09:10:13Z
       
  • Storm overwash of a gravel barrier: Field measurements and XBeach-G
           modelling
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Luis Pedro Almeida, Gerd Masselink, Robert McCall, Paul Russell
      Gravel barriers provide a natural form of coastal protection and flood defence for many sites around the UK and worldwide. Predicting their vulnerability to different storm impact regimes that cause overtopping and overwash is crucial as these processes can lead to hazardous consequences such as inundation of the back of the barrier or breaching. This paper presents the first field measurements of storm overwash events on a gravel beach (Loe Bar, Cornwall, England). High frequency in-situ observations (2Hz) were performed using a 2D laser-scanner and allowed a complete characterization of the overwash flows (velocity and depth) and morphological response along a cross-shore section of the barrier. These novel measurements are used to validate the numerical model XBeach-G, to forecast overwash discharge. Several simulations were performed with XBeach-G to investigate the thresholds for the different storm impact regimes, given a variety of water levels and wave heights. Wave period and wave spectral shape are found to significantly affect these thresholds. While short period waves dissipate most of their energy by breaking before reaching the swash zone and produce short runup excursions, long period waves due to their low steepness arrive at the swash zone unbroken with enhanced heights (due to shoaling) thus promoting large runup excursions. When the offshore wave spectrum has a bimodal shape, wave transformation in shallow water causes the long period peak to dominate the swash giving large runup excursions. Long period waves or strongly bimodal waves result in enhanced runup thereby reducing the thresholds for barrier overtopping or overwashing.

      PubDate: 2016-11-30T09:10:13Z
       
  • Erratum to “Geometrical and mechanical properties of four species of
           northern European brown macroalgae”[Coast. Eng. 84 (2014) 73–80]
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Pierre-Yves Henry, Maike Paul, Rob Thomas


      PubDate: 2016-11-30T09:10:13Z
       
  • Erratum to “Geometrical and mechanical properties of four species of
           northern European brown macroalgae”[Coast. Eng. 84 (2014) 73–80]
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Pierre-Yves Henry, Maike Paul, Rob Thomas


      PubDate: 2016-11-30T09:10:13Z
       
  • Investigation of breaking and non-breaking solitary waves and measurements
           of swash zone dynamics on a 5° beach
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Lisa Smith, Atle Jensen, Geir Pedersen
      This study presents an experimental investigation of plunging breakers on a sloping beach with an inclination of 5.1°. The incident waves are solitary waves with various amplitudes from non-breaking waves to plunging breakers, and the area investigated is the swash zone. PIV (Particle Image Velocimetry) is performed on images captured at four different field of views (FOV). Shoreline position and maximum runup are measured, and are repeatable in both time and height, although cross-sectional variations of the shoreline shape are observed at maximum runup. For non-breaking waves the runup and fluid flow is computed by a boundary integral technique combined with a boundary layer model. Then, there is excellent agreement between the experimental and the computed velocity profiles at the lower region of the beach, while the boundary integral technique overpredicts the maximum runup height severely. For breaking waves the experiments indicate that the motion becomes more irregular as we move further up the beach. In addition, there are more irregularities present for waves with larger amplitude. Length and velocity of air bubbles entrapped by the plunging breakers are extracted from an image series captured with a large FOV. The images showed that a large air bubble remains intact for a time period during runup for the breaking waves.

      PubDate: 2016-11-30T09:10:13Z
       
  • Investigation of breaking and non-breaking solitary waves and measurements
           of swash zone dynamics on a 5° beach
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Lisa Smith, Atle Jensen, Geir Pedersen
      This study presents an experimental investigation of plunging breakers on a sloping beach with an inclination of 5.1°. The incident waves are solitary waves with various amplitudes from non-breaking waves to plunging breakers, and the area investigated is the swash zone. PIV (Particle Image Velocimetry) is performed on images captured at four different field of views (FOV). Shoreline position and maximum runup are measured, and are repeatable in both time and height, although cross-sectional variations of the shoreline shape are observed at maximum runup. For non-breaking waves the runup and fluid flow is computed by a boundary integral technique combined with a boundary layer model. Then, there is excellent agreement between the experimental and the computed velocity profiles at the lower region of the beach, while the boundary integral technique overpredicts the maximum runup height severely. For breaking waves the experiments indicate that the motion becomes more irregular as we move further up the beach. In addition, there are more irregularities present for waves with larger amplitude. Length and velocity of air bubbles entrapped by the plunging breakers are extracted from an image series captured with a large FOV. The images showed that a large air bubble remains intact for a time period during runup for the breaking waves.

      PubDate: 2016-11-30T09:10:13Z
       
  • Wave overtopping at berm breakwaters: Review and sensitivity analysis of
           prediction models
    • Abstract: Publication date: February 2017
      Source:Coastal Engineering, Volume 120
      Author(s): Karthika Pillai, Amir Etemad-Shahidi, Charles Lemckert
      This paper reviews the available models for the estimation of mean wave overtopping rate at berm breakwaters. A sensitivity analysis was conducted on selected models in order to study the influence of input variables on estimated overtopping discharge. The dimensionless crest freeboard is the most significant factor influencing the predicted overtopping rate. The sensitivity of overtopping to wave steepness varies from being insensitive, constant, or a function of dimensionless crest freeboard across the formulae analysed. The berm width and berm level (with respect to the still water level) have lower impact on the predicted overtopping compared to that of the crest freeboard. A case study on the sensitivity of predicted overtopping was carried out on Sirevag and Bakkafjordur berm breakwaters and it illustrated that the existing models are most sensitive to the variables of dimensionless crest freeboard, when it is greater than 1.0; and dimensionless berm width, when it is greater than 2.0. Additionally, the case study demonstrated inconsistencies among the models for predicted overtopping. The sensitivities of the estimated overtopping rates to the governing variables were compared with those obtained from experimental data. Among the models, the sensitivity estimations using the artificial neural network of Van Gent et al. (2007) [58] and the Lykke Andersen (2006) [32] formula were found to be in more reasonable agreement with those of the experimental data. The Van der Meer and Janssen (1994) [56] formula showed oversensitivity to the major governing variables. The results of this study throws light on the disparities in accounting the influence of variables, in the estimated overtopping rate at berm breakwaters, using the existing prediction models.

      PubDate: 2016-11-24T19:05:12Z
       
  • Estimation of incident and reflected components in highly nonlinear
           regular waves
    • Abstract: Publication date: Available online 17 November 2016
      Source:Coastal Engineering
      Author(s): Thomas Lykke Andersen, Mads Røge Eldrup, Peter Frigaard
      Knowledge of the incident and reflected waves present in laboratory experiments is a key issue in order to correctly assess the behaviour of the tested structure. Usual applied reflection separation algorithms are based on linear wave theory. These linear methods might result in unreliable estimates of the incident and reflected waves in case the waves are nonlinear. In the present short paper a new nonlinear reflection separation algorithm optimized for regular waves is presented. The method separates the superharmonics into bound/free and incident/reflected components. The separation in bound and free components is possible because they travel with different celerity. The new method is an extension of the Lin and Huang (2004) method as they used linear dispersion so indirectly assumed the bound waves to be of 2nd order maximum. They did thus not take into account the amplitude dispersive effect of nonlinear waves (3rd and higher order). The present method uses nonlinear wave celerity in order to overcome this limitation. It is shown in the present paper that for highly nonlinear regular waves none of the existing state-of-the-art tools are reliable. The new method showed on the other hand a good match for all of the tested synthetically generated wave conditions including shallow and deep water and proved also to be robust to noise. Even though the new method is developed for horizontal sea bed it is demonstrated to provide reasonable results on numerical data for vertical asymmetric waves on mildly sloping foreshores.

      PubDate: 2016-11-17T15:47:56Z
       
  • The initial morphological response of the Sand Engine: A process-based
           modelling study
    • Abstract: Publication date: January 2017
      Source:Coastal Engineering, Volume 119
      Author(s): Arjen P. Luijendijk, Roshanka Ranasinghe, Matthieu A. de Schipper, Bas A. Huisman, Cilia M. Swinkels, Dirk J.R. Walstra, Marcel J.F. Stive
      Sand nourishments are presently widely applied to maintain or enhance coastal safety and beach width. Over the last decades, global sand nourishment volumes have increased greatly, and the demand for nourishments is anticipated to increase further in coming decades due to sea level rise. With the increase in nourishment size and the request for more complex nourishment shapes, an adequate prediction of the morphodynamic evolution is of major importance. Yet, neither the skill of current state-of-the-art models for such predictions nor the primary drivers that control the evolution are known. This article presents the results of a detailed numerical modelling study undertaken to examine the model skill and the processes governing the initial morphological response of the Sand Engine and the adjacent coastline. The process-based model Delft3D is used to hindcast the first year after completion of the mega-nourishment. The model reproduces measured water levels, velocities and nearshore waves well. The prediction of the morphological evolution is consistent with the measured evolution during the study period, with Brier Skill Scores in the ‘Excellent’ range. The model results clearly indicate that the sand eroded from the main peninsular section of the Sand Engine is deposited along adjacent north and south coastlines, accreting up to 6km of coastline within just one year. Analysis of model results further show that the erosional behaviour of the Sand Engine is linearly dependent on the cumulative wave energy of individual high energy wave events, with the duration of a storm event being more dominant than the maximum wave height occurring during the storm. The integrated erosion volume due to the 12 events with the highest cumulative wave energy density accounts for about 60% of the total eroded volume of the peninsula, indicating that the less energetic wave events, with a higher probability of occurrence, are also important for the initial response of the Sand Engine. A structured model experiment using the verified Delft3D model indicates that wave forcing dominates the initial morphological response of the Sand Engine, accounting for approximately 75% of the total erosion volume in the first year. The vertical tide is the second most important factor accounting for nearly 17% of the total erosion volume, with surge, wind and horizontal tide playing only a minor role.

      PubDate: 2016-11-11T14:11:17Z
       
  • Assessment of runup predictions by empirical models on non-truncated
           beaches on the south-east Australian coast
    • Abstract: Publication date: January 2017
      Source:Coastal Engineering, Volume 119
      Author(s): Alexander L. Atkinson, Hannah E. Power, Theo Moura, Tim Hammond, David P. Callaghan, Tom E. Baldock
      This paper assesses the accuracy of 11 existing runup models against field data collected under moderate wave conditions from 11 non-truncated beaches in New South Wales and Queensland, Australia. Beach types spanned the full range of intermediate beach types from low tide terrace to longshore bar and trough. Model predictions for both the 2% runup exceedance (R 2%) and maximum runup (R max ) were highly variable between models, with predictions shown to vary by a factor of 1.5 for the same incident wave conditions. No single model provided the best predictions on all beaches in the dataset. Overall, model root mean square errors are of the order of 25% of the R 2% value. Models for R 2% derived from field data were shown to be more accurate for predicting runup in the field than those developed from laboratory data, which overestimate the field data significantly. The most accurate existing models for predicting R 2% were those developed by Holman [12] and Vousdoukas et al. [40], with mean RMSE errors of 0.30m or 25%. A new model-of-models for R 2% was developed from a best fit to the predictions from six existing field and one large scale laboratory R 2% data-derived models. It uses the Hunt [17] scaling parameter tan β H o L o and incorporates a setup parameterisation. This model is shown to be as accurate as the Holman and Vousdoukas et al. models across all tidal stages. It also yielded the smallest maximum error across the dataset. The most accurate predictions for R max were given by Hunt [17] but this tended to under predict the observed maximum runup obtained for 15-min records. Mase's [22] model has larger errors but yielded more conservative estimates. Greater observed values of R max are expected with increased record length, leading to greater differences in predicted values. Given the large variation in predictions across all models, however, it is clear that predictions by uncalibrated runup models on a given beach may be prone to significant error and this should be considered when using such models for coastal management purposes. It should be noted that in extreme events, which are lacking in the dataset, runup may truncated by beach scarps, cliffs, and dunes, or may overtop, and as a result, the probability density functions will have different tail shapes. The uncertainty already present in current models is likely to increase in such conditions.

      PubDate: 2016-11-11T14:11:17Z
       
  • Correcting wave reflection estimates in the coastal zone
    • Abstract: Publication date: Available online 4 October 2016
      Source:Coastal Engineering
      Author(s): Kris Inch, Mark Davidson, Gerd Masselink, Paul Russell
      The impact of random noise on an existing two-dimensional method for separating incident and reflected wave spectra using an array of wave gauges is investigated using simulated time series with known wave amplitudes, reflection coefficients, and signal-to-noise ratios. Both the incident and reflected spectra are overestimated by a quantity that can exceed 100% for signal-to-noise ratios less than 1. Consequently, estimated reflection coefficients are also overestimated with larger errors occurring when the known reflection is low. Coherence decreases systematically with increasing noise and this trend is used to develop a mathematical function to correct for the observed bias and provide 95% confidence intervals for incident and reflected spectra and reflection coefficients. The correction technique is shown to be very effective in reducing error by up to ~90%. Field data from a natural beach are used to demonstrate the application of these results; corrected values suggest that reflection coefficients are frequently overestimated by over 50%.

      PubDate: 2016-11-11T14:11:17Z
       
 
 
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