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  Subjects -> ENGINEERING (Total: 2285 journals)
    - CHEMICAL ENGINEERING (192 journals)
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    - ELECTRICAL ENGINEERING (104 journals)
    - ENGINEERING (1206 journals)
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ENGINEERING (1206 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: 18)
AAPG Bulletin     Hybrid Journal   (Followers: 7)
AASRI Procedia     Open Access   (Followers: 15)
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: 245)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
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: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 26)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 29)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 39)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 2)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 5)
AIChE Journal     Hybrid Journal   (Followers: 32)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
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: 17)
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: 8)
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: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 17)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 1)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
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: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
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: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
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: 8)
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: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
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: 4)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 33)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
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: 13)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 27)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 45)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 7)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 8)
CEAS Space Journal     Hybrid Journal   (Followers: 1)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
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: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 24)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
Coatings     Open Access   (Followers: 4)
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: 27)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 265)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 189)
Composites Part B : Engineering     Hybrid Journal   (Followers: 258)
Composites Science and Technology     Hybrid Journal   (Followers: 186)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 7)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 6)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 31)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 7)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 43)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
Corrosion Series     Full-text available via subscription   (Followers: 6)
CT&F Ciencia, Tecnologia y Futuro     Open Access   (Followers: 1)

        1 2 3 4 5 6 7 | Last

Journal Cover Coastal Engineering
  [SJR: 1.999]   [H-I: 74]   [11 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0378-3839
   Published by Elsevier Homepage  [3089 journals]
  • Breaking of ship bores in a Boussinesq-type ship-wake model
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Fengyan Shi, Matt Malej, Jane M. Smith, James T. Kirby
      A numerical study of ship-induced bores is carried out with a focus on soliton generation in different supercritical regimes, and the transition from breaking solitons to a pure bore measured in Gourlay's (2001) laboratory experiments. The fully nonlinear Boussinesq model, FUNWAVE-TVD, with appropriate dissipation schemes, is able to simulate ship-induced broken bores with amplitudes and periods consistent with the measured data. Two breaking dissipation schemes with different breaking criteria (a viscosity dissipation scheme with the surface slope breaking criterion, and a shock-capturing dissipation scheme with the wave height or surface elevation breaking criteria) are examined in a series of numerical experiments. It is found that both models predict soliton generation and the general trend of the transition from breaking solitons at lower Froude numbers to a pure bore at higher Froude numbers. Some differences are identified between the two different breaking schemes, including breaking locations, soliton propagation speed, amplitudes of wakes behind the ship, and the critical Froude number for the transition from a broken undular bore to a pure bore. In general, the viscosity-type breaker with the surface slope criterion performs more consistently with the laboratory observation compared with the shallow water equation-based shock-capturing breaker.

      PubDate: 2017-12-13T03:55:27Z
       
  • Model studies for flocculation of sand-clay mixtures
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Alan J.S. Cuthbertson, Farzin Samsami, Ping Dong
      Results are presented from a combined experimental and numerical study aimed at comparing the flocculation behaviour of purely-cohesive (clay) and mixed (sand-clay) sediment suspensions under equivalent controlled hydrodynamic conditions. The experiments were conducted in a grid-stirred settling column and focussed on measuring the parametric influences of grid-generated shear rate and local suspended sediment concentrations on the time-evolution of the micro- and macrofloc size distributions generated in the column, as well as representative maximal and root-mean-square floc sizes. The results indicate that for kaolin clay suspensions under low-medium shear rates, initial aggregation rates and the peak or quasi-equilibrium floc sizes attained increase with the clay input concentration; this latter effect due to the larger proportion of macroflocs generated within these runs. By contrast, under high shear rates, representative floc sizes for kaolin clay suspensions remain largely unchanged over the experimental duration, with little influence from clay input or in-situ concentrations, and no macroflocs present in the resulting floc size distributions. The addition of the fine sand fraction to the kaolin clay suspensions is shown to reduce both initial aggregation rates and the representative floc sizes attained in the column for runs under low-medium shear rates, whilst having negligible effect on the flocculation behaviour for the sand-clay mixtures under high shear rates. These results suggest that the sand fraction inhibits flocculation at lower shear rates due to an additional floc break-up mechanism resulting from direct sand-clay interactions (e.g. particle-floc collisions). The importance of these inter-fractional (sand-clay) interactions diminishes, in comparison to shear-induced floc break-up, under higher shear conditions. A one dimensional vertical (1DV) model incorporating a population balance equation (PBE) that includes new representation of these multi-fractional (sand-clay) collisions is applied to simulate the kaolin clay and sand-clay settling column tests. In general, the 1DV PBE model predictions provide good agreement with the measured in-situ concentrations and quasi-equilibrium floc sizes attained, but under-predict floc sizes during the initial aggregation phase due to uncertainty with the upper boundary condition in the 1DV model domain. Furthermore, the reliance of the 1DV PBE model predictions on empirical floc break-up rates associated with shear-induced floc fragmentation and multi-fractional (sand-clay) collisions warrants further attention to better define the microscale dynamics of these processes for their improved representation in the PBE model. It is anticipated that this multi-fractional approach represents an improved basis for modelling flocculation processes within natural sedimentary environments, such as estuaries and tidal inlets, where bed sediments often consist of interacting cohesive (i.e. muds) and non-cohesive (i.e. silts, sands) fractions.

      PubDate: 2017-12-13T03:55:27Z
       
  • Modelling of bed sediment composition changes at the lower shoreface of
           the Sand Motor
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): B.J.A. Huisman, B.G. Ruessink, M.A. de Schipper, A.P. Luijendijk, M.J.F. Stive
      Large perturbations in the coastline, such as the 'Sand Motor' nourishment ( ∼ 21 million m3) at the Holland coast, can initiate considerable spatial and temporal changes in the median grain size ( D 50 ) of the sea bed on the lower shoreface. The relevance of hydrodynamic conditions for the development of the heterogeneity in D 50 at large-scale nourishments was assessed with a numerical model (Delft3D), which required a validation against 2.5 years of D 50 measurements. A good representation of the observed spatial pattern of D 50 was obtained independent of a 2DH or 3D approach and initial condition for the D 50 of the bed. Five sediment size fractions and a multi-layer administration of the bed composition were used. The extent and magnitude of the coarsening of the bed is related to the velocity of the horizontal tide, while a far less pronounced coarsening takes place during energetic conditions (i.e. H m 0 ≥ 3 m). Differential suspension behaviour between the size fractions, which are all mobilized at the bed, causes a preferential transport of fine sediment (in alongshore direction) away from the Sand Motor at the lower shoreface (i.e. seaward of MSL -6 m). Storm conditions may induce a partial removal of the coarse top-layer due to mobilization of all of the size fractions and mixing with the relatively fine substrate material. Simulations also show that transport of the fine sand fraction extents to much deeper water than for the medium and coarse sand fractions. Models with multiple sediment fractions are therefore required for the assessment of environmental impacts of large-scale coastal structures or land reclamation's and sediment transport on the lower shoreface.

      PubDate: 2017-12-13T03:55:27Z
       
  • Estimations of wave forces on crown walls based on wave overtopping rates
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Jorge Molines, Maria P. Herrera, Josep R. Medina
      In this study, seven input variables are used to estimate wave forces on the crown wall, and explanatory variables are ranked using neural network techniques. 274 small-scale 2D tests, including both wave overtopping and pressure on crown-wall measurements, were used to calibrate the wave force predictors. Wave overtopping (log Q) was the most relevant variable to estimate horizontal wave forces and overturning moments, while the relative foundation level (F c /L 0p ) was the most relevant variable to estimate wave up-lift forces. The new wave force estimators showed prediction errors slightly higher than the formulas given in the literature, but using fewer parameters and explanatory variables. The range of application of the new formulas is 1.67 < R c /(γf H m0 ) < 6.55, 1.39 <  ξ 0p  < 7.77, 0.36 < γf R u0.1% /R c  < 1.41, 0.00 < (R c -A c )/C h  < 0.59, 2.64 <  L m / G c  < 6.54, 0.00 < F c /L 0p  < 0.03 and −6.00 < logQ < −2.78. Compared to pressure on crown walls, the mean wave overtopping rate is relatively easy to measure in small-scale tests and prototypes. The new estimators of wave forces on the crown wall can be used to indirectly calculate forces on models when only overtopping rates are measured. If wave overtopping is one order of magnitude higher, the wave forces and overturning moments on the crown wall increase between 11% and 60%, considerably reducing the crown wall stability.

      PubDate: 2017-12-13T03:55:27Z
       
  • Numerical modeling of salt marsh morphological change induced by Hurricane
           Sandy
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Kelin Hu, Qin Chen, Hongqing Wang, Ellen K. Hartig, Philip M. Orton
      The salt marshes of Jamaica Bay serve as a recreational outlet for New York City residents, mitigate wave impacts during coastal storms, and provide habitat for critical wildlife species. Hurricanes have been recognized as one of the critical drivers of coastal wetland morphology due to their effects on hydrodynamics and sediment transport, deposition, and erosion processes. In this study, the Delft3D modeling suite was utilized to examine the effects of Hurricane Sandy (2012) on salt marsh morphology in Jamaica Bay. Observed marsh elevation change and accretion from rod Surface Elevation Tables and feldspar Marker Horizons (SET-MH) and hydrodynamic measurements during Hurricane Sandy were used to calibrate and validate the wind-waves-surge-sediment transport-morphology coupled model. The model results agreed well with in situ field measurements. The validated model was then used to detect salt marsh morphological change due to Sandy across Jamaica Bay. Model results indicate that the island-wide morphological changes in the bay's salt marshes due to Sandy were in the range of −30 mm (erosion) to +15 mm (deposition), and spatially complex and heterogeneous. The storm generated paired deposition and erosion patches at local scales. Salt marshes inside the west section of the bay showed erosion overall while marshes inside the east section showed deposition from Sandy. The net sediment amount that Sandy brought into the bay is only about 1% of the total amount of reworked sediment within the bay during the storm. Numerical experiments show that waves and vegetation played a critical role in sediment transport and associated wetland morphological change in Jamaica Bay. Furthermore, without the protection of vegetation, the marsh islands of Jamaica Bay would experience both more erosion and less accretion in coastal storms.

      PubDate: 2017-12-13T03:55:27Z
       
  • The influence of bed friction variability due to land cover on
           storm-driven barrier island morphodynamics
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Davina L. Passeri, Joseph W. Long, Nathaniel G. Plant, Matthew V. Bilskie, Scott C. Hagen
      Variations in bed friction due to land cover type have the potential to influence morphologic change during storm events; the importance of these variations can be studied through numerical simulation and experimentation at locations with sufficient observational data to initialize realistic scenarios, evaluate model accuracy and guide interpretations. Two-dimensional in the horizontal plane (2DH) morphodynamic (XBeach) simulations were conducted to assess morphodynamic sensitivity to spatially varying bed friction at Dauphin Island, AL using hurricanes Ivan (2004) and Katrina (2005) as experimental test cases. For each storm, three bed friction scenarios were simulated: (1) a constant Chezy coefficient across land and water, (2) a constant Chezy coefficient across land and depth-dependent Chezy coefficients across water, and (3) spatially varying Chezy coefficients across land based on land use/land cover (LULC) data and depth-dependent Chezy coefficients across water. Modeled post-storm bed elevations were compared qualitatively and quantitatively with post-storm lidar data. Results showed that implementing spatially varying bed friction influenced the ability of XBeach to accurately simulate morphologic change during both storms. Accounting for frictional effects due to large-scale variations in vegetation and development reduced cross-barrier sediment transport and captured overwash and breaching more accurately. Model output from the spatially varying friction scenarios was used to examine the need for an existing sediment transport limiter, the influence of pre-storm topography and the effects of water level gradients on storm-driven morphodynamics.

      PubDate: 2017-12-13T03:55:27Z
       
  • The evolution of free and bound waves during dispersive focusing in a
           numerical and physical flume
    • Abstract: Publication date: February 2018
      Source:Coastal Engineering, Volume 132
      Author(s): Thomas Vyzikas, Dimitris Stagonas, Eugeny Buldakov, Deborah Greaves
      Since the introduction of the NewWave theory (Lindgren, 1970), focused wave groups are used in physical and numerical studies to investigate the interaction of marine structures and ships with extreme waves. The propagation of such wave groups is associated with high order nonlinearities that can cause considerable deviations from linear and 2 n d order predictions. Consequently, nonlinear numerical models or laboratory tests are needed to accurately describe the evolution of focused wave groups. In the present study, we validate a widely used two-phase Reynolds Averaged Navier-Stokes (RANS) solver realised in OpenFOAM with experimental results for the propagation of steep focused wave groups, using a newly developed methodology based on the separation of harmonics. This approach allows for accurate focusing of wave groups and in-detail examination of the individual evolution of the high order terms, as well as identifying the source of discrepancies between experiments and numerical models. The wave groups comprise long-crested broadbanded Gaussian spectra of increasing steepness propagating in intermediate water depth. The contribution of the nonlinear harmonics to the crest height and overall shape of the wave are also discussed, together with the effect of nonlinear wave interactions on the free-wave spectrum. The rapid growth of 3 r d and 4 t h harmonics near focusing as well as the evolution of the free-wave spectrum, cause departures of up to 29% and 22% from analytic linear and 2 n d order predictions. The present results demonstrate that RANS-VoF solvers constitute accurate models to propagate nearly breaking waves.

      PubDate: 2017-12-13T03:55:27Z
       
  • Numerical modeling of wave runup on steep and mildly sloping natural
           beaches
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Julia W. Fiedler, Pieter B. Smit, Katherine L. Brodie, Jesse McNinch, R.T. Guza
      Runup on ocean beaches includes steady wave setup and oscillating swash, often decomposed into wind generated sea-swell (SS), and lower frequency infragravity (IG) waves. We show that the numerically fast, open-source numerical model 1D SWASH predicts accurately the bulk properties of runup observed on two natural beaches (one steep and one shallow sloped) for a range of incident wave conditions. The runup tongue shape was measured with a scanning lidar, and the waterline location was defined in both the observations and model with a 10 cm depth threshold. Runup is reasonably accurately predicted with energetic (e.g. 5 m significant height) incident waves, even though the assumption of 1D bound waves significantly overpredicts infragravity energy at the offshore boundary in 10 m depth. The model-data comparisons are limited by statistical chatter, often larger in runup than offshore because runup energy is concentrated in the relatively narrow infragravity IG band with low effective degrees of freedom.

      PubDate: 2017-12-13T03:55:27Z
       
  • Distribution of turbulent eddies behind a monopile for vortex lock-on
           condition due to wave current combined flow
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Sayahnya Roy, Koustuv Debnath, Bijoy S. Mazumder
      The paper presents the results of an experimental study on wave current combined flow around a monopile (partially submerged circular cylinder) for a large Reynolds number. Measured instantaneous time series velocity signals (i.e., the sequence of discrete-time dependent velocity data) were analyzed to evaluate the statistical moments. It was found that vortex lock-on takes place when the forcing frequency of the superimposed surface wave is double that of the natural shedding (NS) frequency. Also, the recirculation region almost disappeared for vortex lock-on condition. The vortices generated due to superimposed surface waves increased the turbulence level near the shear layer at the recirculation region. Moreover, the Reynolds shear stress increased near the shear layer at the recirculation region due to vortex lock-on compared to that of NS condition. Further, the Gram-Charlier type joint probability distributions for two variables were estimated to describe the statistical properties of turbulent velocity fluctuations in different co-ordinate directions. Results from wavelet analysis of phased averaged velocity fluctuation suggested that the wave motion could modulate not only the large-scale eddies in the energy containing region, but the moderate scale eddies for the vortex lock-on condition. At the wake region of the monopile for vortex lock-on condition, it was pertinent that the wave motion induced fluctuating eddies of the background flow gained in strength and showed periodic distribution at the NS frequency (half of the induced wave frequency) in the time domain. The comparative study between NS and vortex lock-on condition showed that the induced wave motion can modulate the instantaneous small amplitude values of stream - wise and transverse velocity fluctuations ( u ' v ' ) that occur at the recirculation region.

      PubDate: 2017-11-16T14:06:32Z
       
  • A partial cell technique for modeling the morphological change and scour
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Zhong Peng, Qing-Ping Zou, Pengzhi Lin
      A novel partial cell technique applied on structured grids is developed to track the deformation of water-soil interface associated with beach morphological change and toe scour in front of coastal structures. It allows the use of the same orthogonal structured grids for morphological, sediment transport and hydrodynamic models therefore, has the advantage of consuming less CPU and without the need to adapt grids to the evolving beach morphology. An improved sand-slide model with better mass conservation is introduced to resolve the avalanche behaviour of the sediment motion. The RANS-VOF hydrodynamic model has been extended to cope with complex bathymetry. The newly developed numerical model suite, coupling the RANS-VOF model, a bedload sediment transport model and a morphological model using the partial cell technique, are validated against the analytical solutions and laboratory measurements for different incoming wave conditions, local water depths and bottom slopes. This study reveals the key processes that govern the behaviour of beach morphology change in front of a vertical coastal structure during storms. The model-data comparisons demonstrate the robustness of partial cell technique to capture the movement of the water-soil interface.

      PubDate: 2017-11-16T14:06:32Z
       
  • Drivers of alongshore variable dune erosion during a storm event:
           Observations and modelling
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Kristen D. Splinter, Edward T. Kearney, Ian L. Turner
      The ability to understand and predict alongshore-variable sand dune erosion is key to better coastal management. This study utilizes detailed observations (immediately pre, during and post-storm topography, waves and water levels) collected over a 6-day period at the 3.6 km long Narrabeen-Collaroy beach in south-east Australia, to identify and explore drivers of the highly variable alongshore dune erosion caused by an East Coast Low storm in June 2011. Key characteristics of the immediately pre-storm subaerial morphology obtained by airborne Lidar (beach slope, dune toe elevation, dune height) varied considerably alongshore. Daily airborne Lidar surveys conducted at low tide indicated considerable temporal variability in the evolution of the subaerial beach profile. Despite considerable alongshore variability in the magnitude of modelled inshore wave heights during the storm, it was instead observed that the predominant determinant of maximum dune erosion was the pre-storm dune toe elevation. A simple dune impact model forced with local alongshore-variable inshore wave modelling was found to successfully predict up to 85% of the observed alongshore variability in dune erosion at this site, with this erosion tidally modulated over the 6 days to time periods when the waves were directly impacting the dune. Importantly, alongshore variation in wave height is shown to account for just 10% of the alongshore variability in dune erosion during this storm. These results reconfirm that knowledge of the pre-storm subaerial morphology, in particular the elevation of the dune toe with respect to time-varying water levels during a storm, is a key driver of alongshore variability in the erosion response along dune-backed sandy coastlines.

      PubDate: 2017-11-08T13:15:07Z
       
  • Nonlinear and viscous effects on the hydrodynamic performance of a fixed
           OWC wave energy converter
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Rong-quan Wang, De-zhi Ning, Chong-wei Zhang, Qing-ping Zou, Zhen Liu
      The hydrodynamic performance of a fixed Oscillating Water Column (OWC) device is experimentally and numerically investigated. Based on the time-domain higher-order boundary element method (HOBEM), by introducing an artificial viscosity term in the dynamic free surface boundary condition, a fully nonlinear numerical wave model is used to simulate the hydrodynamic performance of an OWC device. A set of comprehensive experiments for regular waves is carried out to validate the numerical results as well as to investigate the nonlinear effects on the hydrodynamic performance of OWC. The mechanism of the nonlinear phenomenon is investigated based on the analysis of the experimental and numerical results. The influence of the wave nonlinearity and the viscosity on the hydrodynamic efficiency is quantified by comparing the linear and nonlinear numerical results. It was found that the hydrodynamic efficiency increases with the nonlinearity and viscosity when the incident wave amplitude is small. When the incident wave amplitude is large, the hydrodynamic efficiency is reduced by the weakened transmission of the second-order harmonic wave component due to the strong wave nonlinearity. However, when the wave amplitude is between these two regimes, the wave is weakly nonlinear, the efficiency decreases with the wave amplitude due to the combined effect of the nonlinearity and viscosity.

      PubDate: 2017-11-08T13:15:07Z
       
  • Numerical modelling of erosion rates, life span and maintenance volumes of
           mega nourishments
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): P.K. Tonnon, B.J.A. Huisman, G.N. Stam, L.C. van Rijn
      Mega-nourishments, aiming at providing long-term coastal safety, nature qualities and recreational space, have been applied recently at the Holland coast and are considered at various other places in the world. Methods to quickly evaluate the potential and lifetime of these coastal mega nourishments are therefore very much desired, which is the main objective of this research. Two types of mega nourishments can be distinguished: feeder-type mega nourishments may erode freely to feed adjacent coasts for a more natural, dynamic dune growth while permanent mega-nourishments are designed to preserve safety levels and need to maintain their size and shape and thus needs to be nourished themselves. The design and impact assessment studies for both types of mega nourishments require detailed morphological studies to determine the morphological evolution. In this paper 2DH (Delft3D) and 1D (UNIBEST-CL+ and LONGMOR) numerical models were calibrated using data of the Sand Motor mega-nourishment and were then applied to model a series of mega-nourishments with various width over length ratios and volumes in order to derive relations and design graphs for erosion rates, life span and maintenance volumes. These relations and design graphs can be used in project initiation phases and feasibility studies. The magnitude of the modelled wave-driven longshore sediment transport rates in 1D coastline models depend on the representation of wave refraction on the lower shoreface, since a distinction should be made between the non-rotating lower shoreface and active surfzone. It was shown that the life time of nourishments is mainly determined by the dimensions of the nourishment and incoming wave energy.

      PubDate: 2017-11-08T13:15:07Z
       
  • Storm-induced risk assessment: Evaluation of two tools at the regional and
           hotspot scale
    • Abstract: Publication date: Available online 6 November 2017
      Source:Coastal Engineering
      Author(s): O. Ferreira, C. Viavattene, J.A. Jiménez, A. Bolle, L. das Neves, T.A. Plomaritis, R. McCall, A.R. van Dongeren
      Coastal zones are under increasing risk as coastal hazards increase due to climate change and the consequences of these also increase due to on-going economic development. To effectively deal with this increased risk requires the development of validated tools to identify coastal areas of higher risk and to evaluate the effectiveness of disaster risk reduction (DRR) measures. This paper analyses the performance in the application of two tools which have been developed in the RISC-KIT project: the regional Coastal Risk Assessment Framework (CRAF) and a hotspot early warning system coupled with a decision support system (EWS/DSS). The paper discusses the main achievements of the tools as well as improvements needed to support their further use by the coastal community. The CRAF, a tool to identify and rank hotspots of coastal risk at the regional scale, provides useful results for coastal managers and stakeholders. A change over time of the hotspots location and ranking can be analysed as a function of changes on coastal occupation or climate change. This tool is highly dependent on the quality of available information and a major constraint to its application is the relatively poor availability and accessibility of high-quality data, particularly in respect to social-economic indicators, and to lesser extent the physical environment. The EWS/DSS can be used as a warning system to predict potential impacts or to test the effectiveness of risk reduction measures at a given hotspot. This tool provides high resolution results, but needs validation against impact data, which are still scarce. The EWS/DSS tool can be improved by enhancing the vulnerability relationships and detailing the receptors in each area (increasing the detail, but also model simulations). The developed EWS/DSS can be adapted and extended to include a greater range of conditions (including climate change), receptors, hazards and impacts, enhancing disaster preparedness for effective risk reduction for further events or morphological conditions. Despite these concerns, the tools assessed in this paper proved to be valuable instruments for coastal management and risk reduction that can be adopted in a wide range of coastal areas.

      PubDate: 2017-11-08T13:15:07Z
       
  • An impact-oriented Early Warning and Bayesian-based Decision Support
           System for flood risks in Zeebrugge harbour
    • Abstract: Publication date: Available online 3 November 2017
      Source:Coastal Engineering
      Author(s): Annelies Bolle, Luciana das Neves, Steven Smets, Justine Mollaert, Saul Buitrago
      Early Warning Systems (EWS) are nowadays becoming fairly standard in river flood forecasting or in large scale hydro-meteorological predictions. For complex coastal morphodynamic problems or in the vicinity of complex coastal structures, such as harbours, EWS are much less used because they are both technically and computationally still very challenging. To advance beyond the state-of-the-art, the EU FP7 project RISC-KIT (www.risc-kit.eu) is developing prototype EWS which address specifically these topics. This paper describes the prototype EWS which has been developed for the case study site of the harbour of Zeebrugge, situated in Flanders along the Belgian coast, allowing the validation of the newly developed tools. The challenge for this EWS and DSS (Decision Support System) is selecting the right number, type, and detail of the models in order to get a sufficiently detailed and trustable results, while keeping calculation time limited in order to allow fast and frequent predictions. In general, waves inside harbours are a combination of locally generated wind waves and offshore wave penetration at the port entrance. Outside a prediction environment, the conditions inside the harbour could be assessed by superimposing processes. The assessment can be carried out by using a combination of a spectral wave model (i.e. SWAN) for the wind generated waves and a Boussinesq type wave model (i.e. Mike 21 BW) for the offshore wave penetration. Finally, a 2D hydrodynamic model (i.e. TELEMAC) can be used to simulate the overland flooding inside the port facilities. To reproduce these processes under a EWS environment, an additional challenge is to cope with the limitations of the calculation times. This is especially true with the Boussinesq model. A model train that integrates process-based modelling, for wind generated waves, with a smart simplification of the Boussinesq model for the wave penetration effects, is proposed. These wave conditions together with the extreme water levels (including storm surge) can then be used to simulate the overtopping/overflow behaviour for the quays. Finally, the hydrodynamic model TELEMAC is run for the inundations inside the port facilities. The complete model train was integrated into the Deltares Delft-FEWS software for scenario simulating to showcase the potential for real time operations.

      PubDate: 2017-11-08T13:15:07Z
       
  • Comparison of a mid-shelf wave hindcast to ADCP-measured directional
           spectra and their transformation to shallow water
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): William R. Dally
      In conducting a cross-shelf wave transformation experiment off the Atlantic coast of north Florida, a unique opportunity was exploited in which an Acoustic Doppler Current Profiler (ADCP) instrument was installed 30 km offshore at the exact location of one of the archive-nodes of a WAM-like wave hindcast model (OWI3G). A second ADCP was installed 550 m from shore. Approximately 53 days of directional wave spectra collected with the two ADCPs are used to (a) locally test the reliability of a subsequent update of the hindcast, (b) document the loss in energy as the waves crossed the broad, relatively shallow continental shelf between the two instruments, (c) test the ability of the SWAN (Gen2) nearshore wave transformation model to replicate the measurements taken in shallow water when driven by the offshore ADCP spectra, and (d) reassess the spectral transformation results when the offshore hindcast is used as input. In addition to direct comparison of the time series of frequency spectra and the directional distribution of energy, typical spectral parameters are each subjected to standard error tests. Results indicate that the offshore hindcast performs well in replicating significant wave height, fairly well for mean period, but not as reliably for peak period. Directional spreading in deeper water is generally well-represented, although vector mean direction is not, and is believed due to the proximity of the coast to the hindcast node. The nearshore model requires an order-of-magnitude reduction in bed roughness from its default value before agreement in wave energy at the nearshore ADCP can be achieved. Outcomes of the error tests for the hindcast-driven versus the ADCP-driven nearshore results (after roughness calibration) are quite similar, but nevertheless indicate that transformed wave period, wave direction, and directional spreading require improvement.

      PubDate: 2017-11-02T13:01:13Z
       
  • Introduction to RISC-KIT: Resilience-increasing strategies for coasts
    • Abstract: Publication date: Available online 27 October 2017
      Source:Coastal Engineering
      Author(s): Ap van Dongeren, Paolo Ciavola, Grit Martinez, Christophe Viavattene, Tom Bogaard, Oscar Ferreira, Ruth Higgins, Robert McCall
      Recent and historic low-frequency, high-impact events have demonstrated the flood risks faced by exposed coastal areas in Europe and beyond. These coastal zone risks are likely to increase in the future which requires a re-evaluation of coastal disaster risk reduction (DRR) strategies and a new mix of PMP (prevention, e.g., dike protection; mitigation, e.g., limiting construction in flood-prone areas and eco-system based solutions; and preparedness, e.g., Early Warning Systems, EWS) measures. In response to these challenges, the RISC-KIT project has delivered a set of open-source and open-access methods, tools and management approaches to reduce risk and increase resilience to low-frequency, high-impact hydro-meteorological events in the coastal zone (the “RISC-toolKIT”). These products enhance forecasting, prediction and early warning capabilities, improve the assessment of long-term coastal risk and optimise the mix of PMP-measures. In this paper an introduction is provided to the objectives, products, applications and lessons-learned of the RISC-KIT project, which are the subjects of this Special Issue. Subsequent papers provide details on the tools and their application on 10 case study sites in Europe.

      PubDate: 2017-11-02T13:01:13Z
       
  • On the splash-up of tsunami bore impact
    • Abstract: Publication date: January 2018
      Source:Coastal Engineering, Volume 131
      Author(s): Harrison T.-S. Ko, Harry Yeh
      Impulsive forces on a box-shaped structure due to bore impact are investigated experimentally. Experiments are conducted in the laboratory by generating a Gaussian-shaped wave onto a step before impacting structures of three different cross-shore to long-shore length ratios. The relationship between measurements of the splash-up flow on the structure wall and the force measurements is investigated. The pressures are predicted based on the Euler model. Maximum impact forces are found to occur during the run-down phase after the maximum splash-up value is reached. The uniform vertical velocity profile assumption used in the Euler model yields a better estimate for the impact force than the linear and hydrostatic assumptions. In order to verify the pressure distribution during the splash-up flow, we utilize the pressure data collected from a separate experiment in a large-scale laboratory flume. The combined evidence suggests that the flow near the splash-up tip behaves like a solid body projectile.

      PubDate: 2017-10-26T01:22:28Z
       
  • A numerical investigation on nonlinear transformation of obliquely
           incident random waves on plane sloping bottoms
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): Yuxiang Ma, Hongzhou Chen, Xiaozhou Ma, Guohai Dong
      The statistical properties of obliquely incident irregular waves over a planar sloping bottom were investigated numerically by the well-known numerical wave model FUNWAVE 2.0. Irregular waves based on the averaged JONSWAP spectra with various wave heights and peak periods were simulated to propagate over planar bottoms. A wide range of incident angles from 0° though 75° were considered to study the influence of incident angles. It was found that incident angles have a significant influence on the wave nonlinearity. The wavelet-based bicoherence revealed that the degree of triad wave interactions of primary waves and the higher harmonics was apparently weakened by increasing wave incident angles. Importantly, using the simulated data, the Klopman wave height distribution was improved by incorporating the influence of obliquely incident angles. It was found that the improved Klopman distribution shows better performance for describing wave height distributions in shallow water depth. Moreover, two empirical formulae are recommended to reflect the relationship between the skewness and the asymmetry of waves and the Ursell number for obliquely incident waves on plane sloping bottoms.

      PubDate: 2017-10-26T01:22:28Z
       
  • Wave overtopping at berm breakwaters: Experimental study and development
           of prediction formula
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): Karthika Pillai, Amir Etemad-Shahidi, Charles Lemckert
      Prediction of overtopping rate plays a key role in the design and safety assessment of breakwater structures. In this study, the mean wave overtopping rate at hardly and partly reshaping berm breakwaters were investigated by means of small-scale physical model tests. The test program was designed to create a database with a wider range of wave steepness, berm width, berm level and crest level for the hardly/partly reshaping conditions with an initial slope of 1:1.50. The new formula was developed covering the comprehensive test conditions (including existing tests and newly-collected ones) using scaling arguments and data mining techniques. Dimensionless governing parameters were used in the development of the formulae, and it was found that the new formula represented the influence of relative water depth on the wave overtopping rate better than the other prediction models. Accuracy metrics such as RMSE and Bias indicated that the developed formula outperformed the existing prediction models within the range of significant overtopping rates. Moreover, the developed formula is simple and gives better insights into the physical significance of the variables in the overtopping process, and thus it is hoped it will be more appealing for engineering applications.

      PubDate: 2017-10-26T01:22:28Z
       
  • Experiences and results from interdisciplinary collaboration: Utilizing
           qualitative information to formulate disaster risk reduction measures for
           coastal regions
    • Abstract: Publication date: Available online 17 October 2017
      Source:Coastal Engineering
      Author(s): Grit Martinez, Clara Armaroli, Susana Costas, Mitchell D. Harley, Michael Paolisso
      This paper illustrates both the potential and challenges of interdisciplinary collaboration amongst researchers from the social sciences/humanities and the natural sciences/engineering in formulating disaster risk reduction measures for coastal regions. The authors aim to share their experiences of working across different scientific and engineering disciplines in the EU project RISC-KIT to co-produce disaster risk reduction measures suitable for specific regional and local contexts, in this case two coastal study areas in Europe (Porto Garibaldi, Italy and Rio Formosa, Portugal). An overview of the historic-cultural origins of scientific disciplines is first presented, explaining the historical fragmentation of scientific knowledge into natural and social sciences and its associated challenges for prior disaster risk studies – and how the current state of an interdisciplinary approach has emerged. This is followed by an analysis of interdisciplinary collaboration, drawing on the experience and data collected (both quantitative and qualitative) from the two case study areas. The article concludes with suggestions to further overcome the segregation of disciplines within disaster risk studies and projects. The authors found that qualitative data help to understand knowledge, values and behaviours of institutional and non-institutional stakeholders in formulating appropriate risk reduction measures to increase resilience in a local context – and that such data work “hand in hand” with quantitative information. Furthermore, the collection of qualitative data by researchers of the natural science and engineering disciplines has the potential to build bridges between disciplines and to stimulate further investigations, as in this case, to explain contradictions in human behaviour when managing risk.

      PubDate: 2017-10-26T01:22:28Z
       
  • Nonlinear wave dynamics in the presence of mud-induced dissipation on
           Atchafalaya Shelf, Louisiana, USA
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): Ilgar Safak, Alex Sheremet, Justin Davis, James M. Kaihatu
      The interplay between wave nonlinearity and mud-induced dissipation is studied here using wave and sediment transport measurements collected in winter 2008, on the Atchafalaya Shelf, Louisiana, between the 8-m and the 4-m isobaths. This study focuses on the relatively energetic storm that occurred on March 4th (2-m wave height in 8-m water depth), which caused significant bed reworking and left in its wake a 20-cm layer of hindered-settling fluid mud. While the net wave dissipation rate was maximal during the hindered-settling phase after the storm, consistent with previous observations, significant dissipation was observed throughout the storm duration, with a secondary maximum associated with the peak of the storm and the maximum bed-reworking effects. The effects of mud-induced dissipation on the nonlinear shoaling process are investigated here using TRIADS, a newly-developed spectral model for nonlinear shoaling of waves. With mud-parameter values estimated using a crude inverse modeling approach, the model was used to separate the effects of mud-induced dissipation from nonlinear transfers, during both the erosion and deposition phases of bed reworking. Numerical simulations show that nonlinear transfers are always active, even under strong dissipation regimes. Remarkably, they also suggest that heavy mud-induced dissipation causes the nonlinear energy cascade to revert direction, with bulk transfers occurring from high-frequency to low-frequency spectral bands. This supports the hypothesis that the interplay between mud-induced dissipation, which is much more significant than the bottom dissipation over sandy beds, and wave nonlinearity can drain energy from the entire spectrum, and not just from the frequency bands that interact directly with the seafloor. The decay of high-frequency variance induced by the reversal of spectral flux in effect reduces the nonlinearity of the wave field.

      PubDate: 2017-10-14T13:11:38Z
       
  • Effects of dual wavenumber dispersion solutions on a nonlinear
           monochromatic wave-current field
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): David M. Kouskoulas, Yaron Toledo
      An analytical solution for quadratic nonlinear wave-current interactions is derived using a perturbation method. In contrast to existing formulations, it accounts for dual wavenumber solutions of the linear problem for a single frequency and their nonlinear interactions. It is demonstrated that even a small amount of energy present on the second solution will introduce significant quantitative and qualitative differences in the surface elevation. These differences include a shorter wavelength component moving with a lower wave celerity, nonlinear spatial focusing, and a mean water level that varies in space. The second solution is also shown to produce a mechanism which may easily result in localized violations of wave breaking criteria. These weakly nonlinear effects are expected to be relevant to a variety of engineering applications and physical processes.

      PubDate: 2017-10-11T13:05:36Z
       
  • Lagoon water-level oscillations driven by rainfall and wave climate
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): R. González-Villanueva, M. Pérez-Arlucea, S. Costas
      Barrier breaching and subsequent inlet formation represent critical processes that ensure the temporary or permanent connection and transference of water, nutrients, or living organisms between a lagoon and the open sea. Here, we investigate the conditions inducing natural barrier breaching through a 34 months monitoring program of water-level oscillations within a shallow lagoon and the adjacent nearshore, at the Northern coast of the Iberian Peninsula, Louro lagoon. Seven natural openings were identified to have occurred during the three monitored wet seasons, from the 2009 to 2012, (Wet1, Wet2 and Wet3); four in the Wet1, two in the Wet2 and one in the Wet3. The openings were grouped in three types depending on the observed relation between the lagoon water-level (Lwl), the estimated berm height (Bh) and the water-level at the beach (Bwl): (i) openings by lagoon outflow, which include those characterized by Lwl higher than Bh and lower Bwl; (ii) openings by wave inundation, including those induced by Bwl higher than Bh, and (iii) mixed openings, which result from a combination of the two previous conditions. We observed that Lwl is modulated by the rainfall regime (Rf) and can be explained by the accumulated precipitation. We estimated applying runup equations to obtain Bh and Bwl which depend on the wave climate and tidal level. The inlet lifespan was found to be regulated by the wave climate and rainfall regime; in particular barrier sealing was associated with a sudden increase in wave period and a reduction in precipitation. This work proves that the natural openings could be predicted successfully with support to medium term water-level monitoring programs, which in turn may significantly contribute to strategic decision making for management and conservation purposes.

      PubDate: 2017-10-11T13:05:36Z
       
  • Wave runup video motion detection using the Radon Transform
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): Rafael Almar, Chris Blenkinsopp, Luis Pedro Almeida, Rodrigo Cienfuegos, Patricio A. Catalán
      A new method of runup detection from video imagery is introduced and validated at an energetic dissipative beach. The instantaneous waterline is detected from uprush and backwash by using the Radon Transform (RT). The method is compared to conventional color contrast method from RGB images and LiDAR measurements. In our observations, the RT shows better detection skill even for adverse conditions, such as those present on flat dissipative swash zones where contrast is reduced. Because the RT is a proxy of deeper waterline (∼0.1 m) it is less sensitive to lack of contrast due to sand saturation. Moreover, since it is based on motion detection, it is less sensitive to changes in lighting conditions. Overall, the RT offers an attractive alternative for long term automated detection of the runup.

      PubDate: 2017-10-11T13:05:36Z
       
  • A simplified physically-based model for coastal dike and barrier breaching
           by overtopping flow and waves
    • Abstract: Publication date: December 2017
      Source:Coastal Engineering, Volume 130
      Author(s): Weiming Wu, Honghai Li
      The simplified physically-based breach model, DLBreach, has been developed to simulate the overtopping breaching of coastal dikes and barriers, which can occur either from the sea side or the bay side. The breaching process is divided into two stages: intensive breaching and general inlet evolution, in which the flows are calculated using the weir flow equation and the Keulegan equation, respectively. The Keulegan equation is a simplified energy equation for steady nonuniform flow with local head loss due to channel contraction and expansion, revised herein by adding the wind driving force. Empirical formulas are adopted to calculate phase-averaged wave overtopping discharge, wave setup, and wind setup/setdown. The wave overtopping discharge is combined with the surge overflow discharge, and the wave setup and wind setup/setdown are added to the sea and bay water levels for the hydrodynamic and sediment routing. Alongshore sediment is considered as a source boundary condition for the non-equilibrium sediment transport model at the breach. The model has been tested using the 94’ field experiment of sea dike breaching by overflow in the Zwin Channel Estuary, a laboratory experiment of sea dike breaching initiated by wave overtopping, and a field observation of the eight-day breaching and closure event of the Mecox Inlet at eastern Long Island of New York during Sept. 10–18, 1985. The model results agree generally well with the measurements.

      PubDate: 2017-10-03T12:30:24Z
       
  • Coupling cross-shore and longshore sediment transport to model storm
           response along a mixed sand-gravel coast under varying wave directions
    • Abstract: Publication date: November 2017
      Source:Coastal Engineering, Volume 129
      Author(s): Rafael J. Bergillos, Gerd Masselink, Miguel Ortega-Sánchez
      This paper investigates the profile response of a mixed sand-gravel deltaic beach (Playa Granada, southern Spain) forced by storm waves from varying directions. Beach morphology was monitored over a 36-day period with variable wave conditions, and profile response was compared to model predictions using the XBeach-G model and a longshore sediment transport (LST) formulation. XBeach-G was applied over 2-day periods of low energy, south-westerly (SW) storm and south-easterly (SE) storm conditions, and was coupled to LST using a parametric approach which distributes the LST across the swash, surf and nearshore zones. A calibrated wave propagation model (Delft3D) was used to obtain the inshore conditions required to drive the XBeach-G model and the LST formulation. The storm response is clearly influenced by the free-board (difference between the height of the berm and the total run-up) and is also strongly dependent on storm-wave direction, with the SW storm eroding the surveyed area, while the SE storm induced beach accretion. Model results indicate that XBeach-G on its own is capable of adequately reproducing the response of the beach under SW storm conditions ( B S S > 0.95 ), but not under SE storms due to the higher LST gradients at the study location. The combination of XBeach-G and LST fits the measured profiles reasonably well under both SW ( B S S > 0.96 ) and SE ( B S S > 0.88 ) storms, inspiring confidence in the coupled model to predict the storm response under varying wave conditions. The combined XBeach-G/LST model was applied to the entire 6.8-km deltaic coastline to investigate the impact of extreme SW and SE storm events, and the model results reiterate the importance of cross-shore and longshore sediment transport in driving coastal storm response at this location. The approach proposed in this work can be extended to other worldwide coasts highly influenced by both cross-shore and longshore sediment transport, such as beaches with different coastline orientations and/or forced by varying wave directions.

      PubDate: 2017-10-03T12:30:24Z
       
  • Coastal Risk Assessment Framework: Comparison of modelled fluvial and
           marine inundation impacts, Bocca di Magra, Ligurian coast, Italy
    • Abstract: Publication date: Available online 28 September 2017
      Source:Coastal Engineering
      Author(s): Silvia De Angeli, Mirko D'Andrea, Giacomo Cazzola, Enrico Duo, Nicola Rebora
      The identification and classification of critical coastal areas is becoming more and more important from a coastal management point of view, especially considering future climate change. The standardized assessment of multiple hazards and their potential impacts is crucial, in terms of risk management, for those coastal areas where both marine and fluvial hazards can occur. Nevertheless, in Bocca di Magra (Liguria Region, Italy), where both coastal and fluvial flooding can occur, up until now the potential impacts from marine flooding have not been thought to be of importance; only the impact of fluvial flooding has been systematically analysed. Now, however, the Liguria Regional stakeholders have become interested in understanding the potential impact of marine inundations compared to fluvial inundations, applying the CRAF (Coastal Risk Assessment Framework) methodology developed inside the RISC-KIT project. The hazard modelling of coastal and fluvial inundations was used, together with exposure data, to evaluate the direct and systemic impacts generated by both flooding mechanisms separately. An End-User-driven Multi-Criteria Analysis was implemented to compare coastal and fluvial impacts on the same area. For an event with a 1 in 200 year return period, the CRAF predicts that fluvial inundation generates higher impacts, in comparison to the marine one. Even though the impacts in the coastal area are less, the impacted exposed elements are different from those impacted by fluvial inundation and none of them can be excluded from the analysis. This work highlights the need for regional managers to develop combined coastal-fluvial flooding assessments; such actions should be seen as a priority for flood disaster risk management in locations affected by both marine flooding and riverine flash flooding.

      PubDate: 2017-10-03T12:30:24Z
       
  • Regional assessment of storm related overwash and breaching hazards on
           coastal barriers
    • Abstract: Publication date: Available online 28 September 2017
      Source:Coastal Engineering
      Author(s): Theocharis A. Plomaritis, Óscar Ferreira, Susana Costas
      Coastal communities are threatened by the impact of severe storms that may cause significant loss of life and damage to properties. Among the main processes behind such impacts on coastal barriers are the occurrence of overwash and breaching during storm events. In order to estimate potential losses associated with a particular event, the above processes must be properly parameterized. Here, we propose a novel methodology to estimate overwash and breaching hazards suitable for a regional scale analysis (Ø 100 km). For the overwash hazard assessment, the method is based on the application of the approach developed by Donnelly (2008) that allows the parametrisation of the overwash hazard considering both flow velocity and flow depth. Moreover, the inland extension of the associated hazard, which is critical to assess subsequent vulnerability, can also be estimated following this methodology. The proposed method requires the selection of a runup formula validated for the study area, a storm beach profile, a runup lens angle, and a percolation constant for infiltration. To assess the breaching, hazard, a new multivariable evaluation is proposed that allows ranking the potential of breaching. The multivariable evaluation combines overwash and erosion hazards as well as their extensions with the main morphological characteristics of the barrier, resulting in the breaching hazard index, that ranks from 0 to 5 (no breaching to inlet formation). Inland breaching extension is also relevant for the vulnerability assessment. The breaching extension can be estimated using historical or contemporary analogues of the nearest flood deltas. The developed approaches were applied to Ancão Peninsula (Algarve, Portugal) as a demonstration example. The advantages of the present approach are: adaptability to various environments where overwash and/or breaching processes are important, time efficiency on evaluating overwash and breaching hazards, and the assessment of hotspot areas at a regional scale.

      PubDate: 2017-10-03T12:30:24Z
       
  • Clear-water scour and flow field alteration around an inclined pile
    • Abstract: Publication date: November 2017
      Source:Coastal Engineering, Volume 129
      Author(s): Vasileios Kitsikoudis, V.S. Ozgur Kirca, Oral Yagci, Mehmet Furkan Celik
      The present experimental study investigates the scour pattern and the near-wake flow field alteration around an emergent rigid cylinder, which is inclined towards the downstream direction. Three different inclination angles were tested separately, namely 14 ° , 30 ° , and 42 ° with respect to the wall-normal axis. The induced flow and scour patterns were assessed and compared with the well-known case of the emergent upright cylinder (inclination angle 0°). The experiments were conducted for steady flow conditions in a 26 m long recirculating flume and the flow velocity measurements were conducted with an acoustic Doppler velocimeter. For the clear-water scour experiment, a false bed with a sand-pit was installed within the flume and a laser scanner was utilized to render a detailed representation of the scoured bed. The results show how the scouring gets mitigated with increasing inclination angle. Spatial distribution of time-averaged and fluctuation velocity patterns are presented, which exhibit that the vertical mixing gets significantly enhanced behind the inclined cylinder with increasing inclination angle, while the lateral mixing gets weakened at the upper flow region. An upward flow is seen at the immediate downstream of the inclined pile close to the bed, which becomes stronger with the inclination angle. Energy spectra as well as joint frequency distributions of velocity components were analyzed together with the time series, revealing that the inclination of the pile alters the wake significantly. The results further indicate that with increasing inclination angle the pile becomes more streamlined and the vortex shedding gets suppressed.

      PubDate: 2017-09-26T13:21:53Z
       
  • Bedload and suspended load contributions to breaker bar morphodynamics
    • Abstract: Publication date: November 2017
      Source:Coastal Engineering, Volume 129
      Author(s): J. van der Zanden, D.A. van der A, D. Hurther, I. Cáceres, T. O'Donoghue, S.J.M.H. Hulscher, J.S. Ribberink
      This study presents measurements of sheet flow processes, grain sorting, and bedload plus suspended load transport rates around a medium-sand breaker bar in a large-scale wave flume. The results offer insights in effects of wave breaking on bedload and grain sorting processes and in the quantitative contributions by bedload and suspended transport to breaker bar morphodynamics. Sheet flow layer dynamics are highly similar to observations under non-breaking waves, revealing clear effects by velocity asymmetry but no evident effects by breaking-generated turbulence, bed slope, or the cross-shore non-uniform flow. The sheet flow layer thickness can be predicted using existing empirical formulations based on local hydrodynamic forcing. At locations covering the shoaling region up to the bar crest the cross-shore variation in bedload transport rates is explained by variations in wave shape (i.e. velocity skewness and asymmetry). At locations between bar crest and bar trough, bedload transport rate magnitudes correlate positively with bed slope and turbulent kinetic energy. Bedload and suspended load transport rates are of similar magnitude but of opposite sign. Bedload transport is onshore-directed and dominates in the shoaling zone, but after wave breaking, the offshore-directed suspended sediment transport increases in magnitude and exceeds bedload transport rates in the breaking and inner surf zones. Bedload and suspended load transport contribute notably differently to bed profile evolution: bedload transfers sand grains from the offshore slope to the bar crest and additionally leads to erosion of the shoreward bar slope and deposition at the bar trough, while suspended load transport induces an opposite pattern of erosion at the bar trough and accretion at the bar crest. Grain size analysis of suspended sediment samples reveals size-selective entrainment and vertical size segregation in the inner surf zone, but suggest size-indifferent entrainment and vertical mixing by energetic vortices in the breaking region. Size-selective transport by bedload and suspended load leads to a cross-shore coarsening of the bed from shoaling to inner surf zone, with local additional sorting mechanisms around the breaker bar due to bed slope effects.

      PubDate: 2017-09-26T13:21:53Z
       
  • Stability of scour protection due to earthquake-induced liquefaction:
           Centrifuge modelling
    • Abstract: Publication date: November 2017
      Source:Coastal Engineering, Volume 129
      Author(s): D.E. Escribano, A.J. Brennan
      A key aspect of permanent offshore structures is protection against scour. This is typically in the form of a blanket of coarse gravel or cobbles surrounding the structure. These coarse particles are selected for their high resistance to being displaced by strong currents and thus protect the underlying finer sand particles from scour. However, in the event of an earthquake, the foundation sand may be susceptible to some degree of liquefaction. This research investigates the effects of seismic-induced liquefaction over a scour blanket, and if sinking is inhibited by some combination of the additional effective stress imposed by the gravel together with the interlocking resistance that develops when coarse particles are subjected to relative displacements. In order to evaluate the stability of scour protection blankets, a programme of physical modelling was carried out, involving the assessment of different configurations of stone layers over a liquefiable material, and a monopile-type foundation. Models were subjected to scaled base shaking equivalent to earthquake loading. A mass-balance of particle sinkage showed that a filter layer was critical for maintaining the integrity of the armour stones. Based on displacement and pore water pressure measurements, it was found that the presence of the scour protection blankets improved the response of the liquefiable sand under seismic loading, and even inhibited the occurrence of liquefaction. This implies that a well-designed scour protection blanket can assist in protecting against earthquake effects also.

      PubDate: 2017-09-07T12:17:18Z
       
  • Numerical and experimental investigation of hydrodynamic performance of a
           cylindrical dual pontoon-net floating breakwater
    • Abstract: Publication date: November 2017
      Source:Coastal Engineering, Volume 129
      Author(s): Chunyan Ji, Yong Cheng, Ke Yang, Gaidai Oleg
      The use of a simple, inexpensive, and effective type of floating breakwater is increasingly becoming a necessity in shoreline and marine structure protection. This study concerns the hydrodynamic behavior of a dual pontoon floating breakwater (DPFB) when attached to one or more rows of plane net by using physical and numerical models. A two-dimensional (2D) fully nonlinear numerical wave tank (NWT) based on a time higher-order boundary element method (HOBEM) and mixed Eulerian-Lagrangian (MEL) approach is applied to obtain numerical solutions. In the model, Darcy's law is used to represent the porous media of the fluid-net interaction, and some auxiliary functions are introduced, instead of an iterative process using the acceleration potential method. Mesh regridding and interpolation combined with a double collocation node technique are implemented to tackle the mismatch between the meshes on the free surface and the wet body surface. In addition, the numerical model is verified with a series of corresponding experimental tests. Numerical solutions and measurement tests are executed to systematically examine the dependence of the reflection coefficient, transmission coefficient and motion responses on the design parameters, such as net number, net porosity, net height, wavelength and wave amplitude. It is found that the new floating breakwater exhibits a better performance with the optimal design parameters as compared with traditional DPFB, especially for long period and large amplitude waves.

      PubDate: 2017-09-02T10:10:37Z
       
  • Solitary wave-induced forces on horizontal circular cylinders: Laboratory
           experiments and SPH simulations
    • Abstract: Publication date: November 2017
      Source:Coastal Engineering, Volume 129
      Author(s): Francesco Aristodemo, Giuseppe Tripepi, Domenico Davide Meringolo, Paolo Veltri
      This work deals with an experimental and numerical study on the horizontal and vertical hydrodynamic forces induced by solitary waves on submerged horizontal circular cylinders. Laboratory tests were performed in the wave flume of the University of Calabria. A battery of pressure transducers was mounted along the external contour of a cylinder placed at half water depth, while four wave gauges were located close to the cylinder and an ultrasonic sensor behind the paddle to measure its displacement. From the numerical viewpoint, a diffusive weakly-compressible SPH model was adopted. To prevent spurious flows near the cylindrical contour, a packing algorithm has been applied to initialize the SPH fluid particles. The acoustic components occurring in the numerical pressure field were filtered through the application of Wavelet Transform. Experimental and numerical analyses were performed in the inertia-dominated regime where these force components are more relevant than the drag and lift ones. The deviation from the fully inertia regime was highlighted in the simulations by the occurrence of a couple of asymmetric vortices behind the cylinder. The good agreement between experimental and SPH forces and kinematics at the cylinder has allowed the numerical calibration of the hydrodynamic coefficients in the Morison and transverse semi-empirical equations by different time-domain methods. For engineering purposes, we propose simple empirical formulas based on the knowledge of wave amplitude to calculate the hydrodynamic coefficients.

      PubDate: 2017-09-02T10:10:37Z
       
  • Tsunami-induced scour around monopile foundations
    • Abstract: Publication date: November 2017
      Source:Coastal Engineering, Volume 129
      Author(s): Bjarke Eltard Larsen, David R. Fuhrman, Cüneyt Baykal, B. Mutlu Sumer
      A fully-coupled (hydrodynamic and morphologic) numerical model is presented, and utilized for the simulation of tsunami-induced scour around a monopile structure, representative of those commonly utilized as offshore wind turbine foundations at moderate depths i.e. for depths less than 30 m. The model is based on solutions to Reynolds-averaged Navier-Stokes equations, coupled with two-equation k − ω turbulence closure, with additional bed and suspended load descriptions forming the basis for sea bed morphology. The model is first validated for flow, bed shear stresses, and scour within a steady current, where a generally excellent match with experimentally-based results is found. A methodology for maintaining and assessing hydrodynamic and morphologic similarity between field and (laboratory) model-scale tsunami events is then presented, combining diameter-based Froude number similarity with that based on the dimensionless wave boundary layer thickness-to-monopile diameter ratio. This methodology is utilized directly in the selection of governing tsunami wave parameters (i.e. velocity magnitude and period) used for subsequent simulation within the numerical model, with the tsunami-induced flow modelled as a long sinusoidally-varying current. The flow, sediment transport, and scour processes beneath up to ten tsunami waves are simulated in succession. These illustrate a generally accumulative scour process i.e. a relatively rapid scour induced by the leading wave, with an additional build-up of the scour depth during additional trailing waves. The resulting scour seems to approach an equilibrium value after sufficient time duration, which corresponds reasonably to that predicted by existing steady-current scour depth expressions, after accounting for the finite boundary layer thickness induced by the unsteady tsunami wave, i.e. it is important to incorporate both current-like, as well as wave-like aspects of the long tsunami event. Based on the simulated results, a simple methodology for predicting the tsunami-induced scour depth in engineering practice is finally developed. This methodology is demonstrated to match the predicted scour development for all of the simulated flows considered, ranging from the series of transient tsunami waves to the steady-current limit.

      PubDate: 2017-09-02T10:10:37Z
       
  • Three-dimensional modeling of wave-induced residual seabed response around
           a mono-pile foundation
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): H.Y. Zhao, D.-S. Jeng, C.C. Liao, J.F. Zhu
      Recently, behavior of large-diameter mono-pile foundations for offshore wind turbines under long-term cyclic wave loading has attracted great attentions from coastal engineers. In this study, a three-dimensional integrated numerical model is developed to investigate the wave-induced seabed response around a monopile foundation. In the model, the Reynolds-Averaged Navier-Stokes (RANS) equations are used for the mean fluid flow, while the Biots consolidation equations are used for the solid-pore fluid interaction in a porous seabed. The monopile is considered as a single phase medium and behaves under a linear elastic law. To reproduce the residual soil behavior under cyclic shearing induced by ocean waves as well as structural rocking motions, a poro-elastoplastic model is adopted, in which the consolidation analysis of seabed foundation under gravitational forces including the body force of structure is pre-assessed and incorporated. The present numerical framework was first validated against several laboratory experiments and obtaining fairly good agreements. Based on the proposed model, failure of monopile foundation caused by liquefaction due to the buildup of pore water pressure under cyclic shearing is investigated. Numerical results indicate that the potential areas for residual pore pressure development and the resulting liquefaction are most pronounced in the vicinity of the monopile following the wave propagation direction, which is caused by waves as well as the rocking motion of the structure induced by the wave impact. Parametric studies indicate that there is no possibility of generating soil liquefaction below the pile bottom in the vicinity of the mono-pile even under large waves.

      PubDate: 2017-09-02T10:10:37Z
       
  • Experimental investigation of turbulent wave boundary layers under
           irregular coastal waves
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): Jing Yuan, Sunil Manohar Dash
      In this study full-scale experiments of wave boundary layers under irregular coastal waves are conducted using an oscillatory water tunnel. The flow conditions cover two rough bottoms, three types of wave shapes, i.e. sinusoidal, skewed and asymmetric waves, and two types of irregular-wave sequences. The instantaneous turbulent velocity fields are measured with a 2-dimensional Particle Image Velocimetry system. The measured turbulence statistical values show that the residual turbulence at the end of wave cycle can persist into the next wave cycle, until the next cycle's self-produced turbulence becomes sufficiently strong. Consequently, the Reynolds-averaged flow at the beginning of a wave cycle can behave as if the flow “memorizes” the previous wave cycle. However, this memory effect quickly vanishes, and therefore does not have a significant influence on some key boundary layer characteristics, e.g. bottom shear stress. For irregular wave boundary layers with skewed and asymmetric free-stream velocities, the measured mean current and the associated mean bottom shear stress confirm the existence of a well-known boundary layer streaming due to the imbalance of turbulence between the two halves of a wave cycle, and the measurements of bottom shear stress of individual waves closely resemble those for periodic-wave conditions. These experimental results suggest that modeling irregular wave boundary layers in a wave-by-wave manner is plausible.

      PubDate: 2017-09-02T10:10:37Z
       
  • High-resolution monitoring of wave transformation in the surf zone using a
           LiDAR scanner array
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): Kévin Martins, Chris E. Blenkinsopp, Hannah E. Power, Brittany Bruder, Jack A. Puleo, Erwin W.J. Bergsma
      Understanding of breaking and broken waves is key for the prediction of nearshore sediment transport and coastal hazards, however the difficulty of obtaining measurements of highly unsteady nearshore waves has limited the availability of field data. This paper reports on a novel field experiment designed to capture the time-varying free-surface throughout the surf and swash zones was conducted on a dissipative sandy beach using an array of 2D LiDAR scanners. Three scanners were deployed from the pier at Saltburn-by-the-Sea, UK for a 6 day period to monitor the surface elevation of nearshore waves from the break point to the runup limit at temporal and spatial resolutions (order of centimetres) rarely achieved in field conditions. The experimental setup and the procedure to obtain a continuous time series of surface elevation and wave geometry is described. A new method to accurately determine the break point location is presented and compared to existing methodologies.

      PubDate: 2017-09-02T10:10:37Z
       
  • An experimentally validated approach for evaluating tsunami inundation
           forces on rectangular buildings
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): A.S.J. Foster, T. Rossetto, W. Allsop
      This paper presents an experimentally validated, closed-form set of equations for predicting forces on rectangular buildings impinged by nominally unsteady tsunami inundation flows. The shallow water waves that drive the tsunami inundation flows described in this paper are generated using a novel tsunami simulator, uniquely capable of generating very long period waves featuring the characteristic draw-down of real-world tsunami. We describe an experimental study of the forces acting on a rectangular building occupying 10–80% of a channel, fixed in a free-surface-channel flow driven by shallow water waves with periods of 20–240 s. An idealised topography and a 1:50 Froude scale are adopted. A one dimensional model based upon open-channel flow principles is proposed for unsteady flows driven by prototype tsunami waves, providing empirical estimates for drag and hydrostatic coefficients. It is observed that the pressure field around the buildings is hydrostatic irrespective of the flow being steady or unsteady. An empirically derived force prediction equation, dependent upon the Froude number of the incoming flow and blocking fraction is presented, which provides good agreement with the experimental results. The equations presented in this paper will provide engineers, tsunami modellers, and risk evaluation experts with a convenient method of tsunami inundation force determination without recourse to computationally expensive multi-scale numerical models.

      PubDate: 2017-09-02T10:10:37Z
       
  • Experimental modeling of horizontal and vertical wave forces on an
           elevated coastal structure
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): Hyoungsu Park, Tori Tomiczek, Daniel T. Cox, John W. van de Lindt, Pedro Lomonaco
      A large-scale physical model was created in Oregon State University's Large Wave Flume to collect an extensive dataset measuring wave-induced horizontal and vertical forces on an idealized coastal structure. Water depth was held constant while wave conditions included regular, irregular, and transient (tsunami-like) waves with different significant wave heights and peak periods for each test. The elevation of the base of the test specimen with respect to the stillwater depth (air gap) was also varied from at-grade to 0.28 m above the stillwater level to better understand the effects of raising or lowering a nearshore structure on increasing or decreasing the horizontal and vertical wave forces. Results indicate that while both horizontal and vertical forces tend to increase with increasing significant wave height, the maximum and top 0.4% of forces increased disproportionally to other characteristic values such as the mean or top 10%. As expected, the horizontal force increased as the test specimen was more deeply submerged and decreased as the structure was elevated to larger air gaps above the stillwater level. However, this trend was not true for the vertical force, which was maximized when the elevation of the base of the structure was equal to the elevation of the stillwater depth. Small wave heights were characterized by low horizontal to vertical force ratios, highlighting the importance of considering vertical wave forces in addition to horizontal wave forces in the design of coastal structures. The findings and data presented here may be used by city planners, engineers, and numerical modelers, for future analyses, informed coastal design, and numerical benchmarking to work toward enabling more resilient nearcoast structures.

      PubDate: 2017-09-02T10:10:37Z
       
  • Extreme wave groups in a wave flume: Controlled generation and breaking
           onset
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): Eugeny Buldakov, Dimitris Stagonas, Richard Simons
      Extreme waves in random seas are usually breaking or close to breaking. Understanding the kinematics and evolution of such waves is important for determining loads on offshore structures. Controlled repeatable generation of realistic breaking waves in wave flume experiments is a difficult but important task. It is rather easy to generate an arbitrary breaking wave, but to the authors' knowledge there is no methodology for accurate generation of a wave group with a pre-defined spectrum related to a modelled sea state with spilling breaking at a prescribed position. Such waves can be used to model extreme breaking waves in a random sea and their interaction with structures. This paper offers such a methodology. The key feature of the method is the application of an iterative focussing procedure to a linearised amplitude spectrum rather than to a full nonlinear spectrum. The linearised spectrum is obtained using a harmonics separation technique and the general derivation of the method is given for an arbitrary number of components. The procedure is applied to generate focussed wave groups with amplitudes increased in small steps until local crest breaking occurs. As a result, the highest non-breaking waves and weakly breaking waves are generated for otherwise identical conditions. The methodology is applied for four different wave spectra of the same peak frequency: JONSWAP, Pierson-Moskowitz, wide and narrow band Gaussian. It is found that steepness of the limiting breaking wave depends strongly on the choice of wave group spectrum. The results demonstrate that neglecting spectral properties of design waves may lead to misrepresentation of their breaking behaviour.

      PubDate: 2017-09-02T10:10:37Z
       
  • Wavenumber-frequency analysis of landslide-generated tsunamis at a conical
           island. Part II: EOF and modal analysis
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): Giorgio Bellotti, Alessandro Romano
      In this paper the Empirical Orthogonal Function (EOF) method is applied to extract from the experimental data, related to landslide-tsunamis around the coast of a conical island, the spatial modes that contribute to the wave field. For each mode the wavenumber and the frequency are calculated by analyzing the shape along the coast and the time function. The relevant modes are then compared with those obtained through numerical eigenanalysis of the long wave equation around the considered island. It was possible to associate each EOF mode with some eigenvectors and the corresponding eigenfrequencies, both on the basis of the spatial shape, the wavenumber calculated along the coast and the frequency. Results confirm that landslide-generated waves propagate along the coast as trapped edge waves and the zero-th order mode is the most important. Further of exploring the physics, it is believed that this paper can be of use as some of the most relevant and straightforward techniques for modal identification are applied to the same problem and dataset.

      PubDate: 2017-09-02T10:10:37Z
       
  • Morphological hysteresis in the evolution of beach profiles under
           sequences of wave climates - Part 1; observations
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): T.E. Baldock, F. Birrien, A. Atkinson, T. Shimamoto, S. Wu, D.P. Callaghan, P. Nielsen
      Novel series of experiments are presented that demonstrate morphological hysteresis in the evolution to equilibrium of beach profiles under sequences of different wave climates. The experiments were conducted in a wave flume at medium scale using both monochromatic and random waves, representing 2D conditions. Beach profiles were obtained with high spatial resolution at frequent intervals with a laser profiler, from which shoreline location, bar position and sediment transport rates were derived. Experiments were conducted for sequences of wave climates, where a sequence comprised of 6–13 sequential tests, each commencing with the beach profile from the preceding test. Each test was run until equilibrium conditions were obtained and had a constant wave height, increased or decreased relative to the preceding test. Cyclical conditions were also included, with erosive and accretive wave conditions of short durations alternating through multiple cycles, so that equilibrium conditions were not reached during a test. With a sequence of increasing wave heights, the relationship between the shoreline position and the bulk cross-shore sediment transport, at equilibrium, was non-monotonic, indicating a maximum in the landward sediment transport rate. For test series comprised of a sequence of increasing wave heights followed by a sequence of decreasing wave heights, morphological hysteresis was observed in the equilibrium shoreline position and bulk cross-shore sediment transport, such that shoreline recession, or offshore transport, continued in some instances after reductions in wave height. This is inconsistent with classical equilibrium type shoreline evolution models. However, when equilibrium conditions were not reached, in the cyclic sequences, no such morphological hysteresis was observed and a dynamic equilibrium is reached. The morphological hysteresis occurs because of the decay, stranding, or increased relative depth, of the breaker bar following a reduction in wave height, often in conjunction with a new breaker bar generated by further offshore transport in the inner surf zone. Similar sequences of morphological response are evident in field data and larger scale tests in the literature. Finally, it is shown that the morphological hysteresis can be explained using the classical equilibrium beach state model of Wright et al. (1985) by introducing the concept of a subsequent alternate active beach state, which may occur following a change in wave conditions.

      PubDate: 2017-09-02T10:10:37Z
       
  • Managing coastal erosion under climate change at the regional scale
    • Abstract: Publication date: October 2017
      Source:Coastal Engineering, Volume 128
      Author(s): Alexandra Toimil, Inigo J. Losada, Paula Camus, Pedro Díaz-Simal
      This study presents a comprehensive methodology that addresses climate change–induced coastal erosion at the regional scale O (100 km). The use of climate data with high space-time resolution enabled the reconstruction of the shoreline response to cross-shore forcing both historically and throughout the twenty-first century. Cross section–based equilibrium models were combined to assess beach erosion induced by local waves, storm surge, astronomical tide and mean sea-level rise. The approach incorporates the potential impacts that tidal inlets could have on the long-term evolution of adjacent beaches as sink terms in the beaches’ budget. The methodology provides probabilistic estimates of coastline recession while accounting for sea level rise uncertainty, both of which are essential aspects for establishing adaptation priorities and efficient fund allocation. The outlined assessment was undertaken on 57 sandy beaches along a 345 km coastline stretch in Asturias, a region in the northwest of Spain open to the Atlantic.

      PubDate: 2017-09-02T10:10:37Z
       
 
 
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