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1
Chakrabarti, Subrata K. "Measurement and Analysis of Laboratory Generated Steep Waves." Journal of Offshore Mechanics and Arctic Engineering 125, no. 1 (February 1, 2003): 17–24. http://dx.doi.org/10.1115/1.1556403.
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In many offshore locations, storm generated steep waves are common and the survival of offshore structures in their presence is an important design condition. The design environment in depth-limited waters often includes waves of breaking and near-breaking conditions, in which currents may be present. Experiments were carried out in a wave tank with simulated steep waves with and without steady in-line current in which the wave profiles and the corresponding kinematics were simultaneously measured. The waves included both regular and random waves and often approached the breaking wave height for the water depth. These waves were analyzed by higher-order wave theory. In particular, the regular waves were simulated by the regular and irregular stream function theory. Especially steep wave profiles within the random waves were computed using the irregular stream function theory. The theory allows inclusion of steady current in its formulation for computation of wave kinematics. The correlation of the measured wave kinematics with the higher-order stream function wave theory showed that the wave theory could predict the kinematics of these steep waves (with and without the presence of current) well. However, in breaking waves, the vertical water particle velocity was not predicted well, especially near the trough. The effect of breaking and near-breaking steep waves on a fixed vertical caisson was also studied. The forces measured on the vertical caisson from the wave tank testing were analyzed to determine the effect of these waves and currents on the forces. It was found that the measured forces (and overturning moments) on the caisson model matched fairly well by the proper choice of force coefficients from the design guideline and the nonlinear stream function theory of appropriate order.
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Funke, E. R., E. P. D. Mansard, and G. Dai. "REALIZABLE WAVE PARAMETERS IN A LABORATORY FLUME." Coastal Engineering Proceedings 1, no. 21 (January 29, 1988): 62. http://dx.doi.org/10.9753/icce.v21.62.
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In order to establish a sound basis for the methodology deployed for the generation of realistic waves under laboratory conditions, a comparison is presented between numerical and physical realizations derived from the Random Phase and the Random Complex Spectrum method for wave synthesis. The comparisons are made in terms of 12 critical wave parameters, including three wave grouping parameters. The results indicate that, for the physical realizations of the limited conditions tested, the two methods give compatible results which fall within the expected band of variability. All physical waves undergo some evolutionary change during propagation which affects predominantly the spectral characteristics. For physical waves produced by the Random Phase method, this change increases the variability of some wave parameters. A sample analysis of one case, applying second order wave and wave generation theory to a numerical simulation, suggests that certain differences between numerical and physical simulations can be explained by non-linear wave theory.
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Harry, Matthew, Hong Zhang, and Gildas Colleter. "REMOTELY SENSED DATA FOR WAVE PROFILE ANALYSIS." Coastal Engineering Proceedings 1, no. 33 (December 14, 2012): 45. http://dx.doi.org/10.9753/icce.v33.waves.45.
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Laser scanning technology (LiDAR) is a form of remote sensing from which a water surface can be measured rapidly and accurately without in-situ sensors. An experimental setup for the measurement of waves in a wave flume is detailed with an analysis of various wave parameters. The experiments function as a source of reliable laboratory controlled data while the data analysis presents the range of research fields that the data can be applied to.
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Hughes, Steven A. "Laboratory wave reflection analysis using co-located gages." Coastal Engineering 20, no. 3-4 (September 1993): 223–47. http://dx.doi.org/10.1016/0378-3839(93)90003-q.
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Leykin, I. A., M. A. Donelan, R. H. Mellen, and D. J. McLaughlin. "Asymmetry of wind waves studied in a laboratory tank." Nonlinear Processes in Geophysics 2, no. 3/4 (December 31, 1995): 280–89. http://dx.doi.org/10.5194/npg-2-280-1995.
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Abstract. Asymmetry of wind waves was studied in laboratory tank tinder varied wind and fetch conditions using both bispectral analysis of wave records and third-order statistics of the surface elevation. It is found skewness S (the normalized third-order moment of surface elevation describing the horizontal asymmetry waves) varies only slightly with the inverse wave u*/Cm (where u* is the air friction velocity and Cm is phase speed of the dominant waves). At the same time asymmetry A, which is determined from the Hilbert transform of the wave record and characterizes the skewness of the rate of change of surface elevation, increase consistently in magnitude with the ratio u*/Cm. This suggests that nonlinear distortion of the wave profile determined by the degree of wind forcing and is a sensitive indicator of wind-wave interaction processes. It is shown that the asymmetric profile of waves can described within the frameworks of the nonlinear nonspectral concept (Plate, 1972; Lake and Yuen, 197 according to which the wind-wave field can be represented as a coherent bound-wave system consisting mainly of dominant component w. and its harmonics propagating with the same speed C. , as observed by Ramamonjiaris and Coantic (1976). The phase shift between o). harmonics is found and shown to increase with the asymmetry of the waves.
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Abroug, Iskander, Nizar Abcha, Armelle Jarno, and François Marin. "Laboratory study of non-linear wave–wave interactions of extreme focused waves in the nearshore zone." Natural Hazards and Earth System Sciences 20, no. 12 (December 3, 2020): 3279–91. http://dx.doi.org/10.5194/nhess-20-3279-2020.
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Abstract. Extreme waves play a crucial role in marine inundation hazards and coastal erosion. Prediction of non-linear wave–wave interactions is crucial in assessing the propagation of shallow water extreme waves in coastal regions. In this article, we experimentally study non-linear wave–wave interactions of large-amplitude focused wave groups propagating in a two-dimensional wave flume over a mild slope (β=1:25). The influence of the frequency spectrum and the steepness on the non-linear interactions of focused waves are examined. The generated wave trains correspond to Pierson–Moskowitz and JONSWAP (γ=3.3 or γ=7) spectra. Subsequently, we experimentally approach this problem by the use of a bispectral analysis applied on short time series, via the wavelet-based bicoherence parameter, which identifies and quantifies the phase coupling resulting from non-resonant or bound triad interactions with the peak frequency. The bispectral analysis shows that the phase coupling increases gradually and approaches 1 just prior to breaking, accordingly with the spectrum broadening and the energy increase in high-frequency components. Downstream breaking, the values of phase coupling between the peak frequency and its higher harmonics decrease drastically, and the bicoherence spectrum becomes less structured.
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Chen, Jie, Chang Bo Jiang, Hu Ying Liu, and Zhi Yuan Wu. "Laboratory Investigation on Tsunami Wave Runup." Applied Mechanics and Materials 212-213 (October 2012): 336–40. http://dx.doi.org/10.4028/www.scientific.net/amm.212-213.336.
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The 2D laboratory experiments were performed to investigate tsunami wave runup on the combined sand beach. The N-wave was generated in three different water depths. The water surface elevations, maximum elevation of runup and snapshots of wave uprush and back wash were measured. The theoretical analysis of runup was presented. The results showed that uprush water wave had a decelerate process. The maximum elevation of runup R depends on incident wave height H and R is linear relationship with H plus water depth h.
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Shen, Y., R. Lindenbergh, B. Hofland, and R. Kramer. "CHANGE ANALYSIS OF LASER SCANS OF LABORATORY ROCK SLOPES SUBJECT TO WAVE ATTACK TESTING." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W4 (September 13, 2017): 139–47. http://dx.doi.org/10.5194/isprs-annals-iv-2-w4-139-2017.
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For better understanding how coastal structures with gentle slopes behave during high energy events, a wave attack experiment representing a storm of 3000 waves was performed in a flume facility. Two setups with different steepness of slope were compared under the same conditions. In order to quantify changes in the rock slopes after the wave attack, a terrestrial laser scanner was used to obtain 3D coordinates of the rock surface before and after each experiment. Next, through a series of processing steps, the point clouds were converted to a suitable 2D raster for change analysis. This allowed to estimate detailed and quantitative change information. The results indicate that the area around the artificial coast line, defined as the intersection between sloped surface and wave surface, is most strongly affected by wave attacks. As the distances from the sloped surface to the waves are shorter, changes for the mildly sloped surface, slope 1 (1 : 10), are distributed over a larger area compared to the changes for the more steeply sloped surface, slope 2 (1 : 5). The results of this experiment show that terrestrial laser scanning is an effective and feasible method for change analysis of rock slopes in a laboratory setting. Most striking results from a process point of view is that the transport direction of the rocks change between the two different slopes: from seaward transport for the steeper slope to landward transport for the milder slope.
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Santon, L. "GRAPHICAL RECORDING OF WAVE PROFILES IN THE LABORATORY; HARMONIC ANALYSIS." Coastal Engineering Proceedings 1, no. 5 (January 29, 2011): 15. http://dx.doi.org/10.9753/icce.v5.15.
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We have developed a laboratory wave recorder of great simplicity which plots a wave profile to a scale which can be either 1 or 3 for the amplitude and which varies between 0,5 and 1 for the horizontal distances.
The apparatus, the principle of which we have already described at a time when we had not proved all its possibilities, has shown itself to be extremely sensitive for the study of fine phenomena.
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Kraskowski, Marek, Katarzyna Pastwa, Sebastian Kowalczyk, and Tomasz Marcinkowski. "Numerical and experimental analysis of the wave induced forces on the tripod support structure. Laboratory study." Biuletyn Instytutu Morskiego 32, no. 1 (December 31, 2017): 21–29. http://dx.doi.org/10.5604/12307424.1224269.
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The presented work was realized within the framework of the AQUILO project, aiming in creating the base of knowledge for prospective future investments in offshore wind energy on Baltic Sea. The presented part of the work is focused on the experimental validation of numerical method of evaluation of the wave-induced forces on the bottom-mounted support structure of the offshore wind turbine. The experimental setup and measurement equipment, including in-house developed 6-DOF (six degree of freedom) dynamometer, are described. As a result, comparison of performance of different methods of evaluation of wave loads for wide range of parameters is presented. The results of experiments and numerical analyses are fairly consistent; largest discrepancy occurred at lowest wave frequencies, i.e. largest wave lengths. This may result from increased relative error of measurements for very long waves in relatively short tank.
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PEIRSON, WILLIAM L., and ANDREW W. GARCIA. "On the wind-induced growth of slow water waves of finite steepness." Journal of Fluid Mechanics 608 (July 11, 2008): 243–74. http://dx.doi.org/10.1017/s002211200800205x.
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Determining characteristic growth rates for water waves travelling more slowly than the wind has continued to be a key unresolved problem of air–sea interaction for over half a century. Analysis of previously reported and recently acquired laboratory wave data shows a systematic decline in normalized wave growth with increasing mean wave steepness that has not previously been identified. The normalized growth dynamic range is comparable with previously observed scatter amongst other laboratory data gathered in the slow wave range. Strong normalized growth rates are observed at low wave steepnesses, implying an efficient wave-coherent tangential stress contribution. Data obtained during this study show quantitative agreement with the predictions of others of the interactions between short wind waves and the longer lower-frequency waves. Measured normalized wave growth rates are consistent with numerically predicted growth due to wave drag augmented by significant wave-coherent tangential stress.
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Zhou, Hao, Xiumei Tan, Ziwen Teng, Lingjun Du, and Hongxu Zhou. "EPG analysis of stylet penetration preference of woolly apple aphid on different parts of apple trees." PLOS ONE 16, no. 8 (August 24, 2021): e0256641. http://dx.doi.org/10.1371/journal.pone.0256641.
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Woolly apple aphid (WAA), Eriosoma lanigerum (Hausmann), is an important global pest that feeds on Malus species. We studied the feeding preference of WAA on apple trees in the field for two consecutive years and in the laboratory we used electronic penetration graphs (EPG) to record the stylet penetration behavior of WAA on different parts of apple trees. We found that in the field WAA fed primarily on twigs and branches, not on leaves and fruits. Six EPG waveforms were produced during WAA probing on shoots, trunks and leaves of apple trees, including the non-penetration wave (np), the stylet pathway phase wave (C), the intracellular feeding wave (pd), the xylem feeding wave (G), waves indicative of release of saliva into the phloem (E1), and a wave indicative of ingestion from phloem (E2). In the laboratory, aphids only successfully fed on shoots, trunks and leaves, not on fruits. The EPG parameters on the phloem of shoots were significantly higher than those on trunks, indicating WAA prefer to feed on shoots. These laboratory findings explain the relative field feeding preference of WAA on different parts of apple trees, which occurs primarily on branches, barks, and young twigs in orchards, especially on young twigs.
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He, Jian Ping. "Research and Analysis on Rock Acoustic Emission Wave Characteristics." Applied Mechanics and Materials 638-640 (September 2014): 534–37. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.534.
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Analyzing wave behavior on acoustic emission laboratory tests from relationship between stress and AE rate , the rock AE signal wave in laboratory is decomposed into high and low frequency elements. Analysis and compare with the details elements include, the approximation elements and original AE wave, the results show that rock AE wave characteristics are not same in the course of transform fracture on stages, found AE wave characteristics storehouse, it is a matter of great significance for utilizing monitoring and prediction regularity and development trend in the course of fracture transform. The error between the original signal and the signal of wave coefficient of the approximation elements reconstructed is minor to, wavelet analysis makes accuracy and reliability of rock AE wave characteristics monitoring and prediction improved, States that wavelet analysis is a great efficiency method.
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de Bakker, A. T. M., T. H. C. Herbers, P. B. Smit, M. F. S. Tissier, and B. G. Ruessink. "Nonlinear Infragravity–Wave Interactions on a Gently Sloping Laboratory Beach." Journal of Physical Oceanography 45, no. 2 (February 2015): 589–605. http://dx.doi.org/10.1175/jpo-d-14-0186.1.
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AbstractA high-resolution dataset of three irregular wave conditions collected on a gently sloping laboratory beach is analyzed to study nonlinear energy transfers involving infragravity frequencies. This study uses bispectral analysis to identify the dominant, nonlinear interactions and estimate energy transfers to investigate energy flows within the spectra. Energy flows are identified by dividing transfers into four types of triad interactions, with triads including one, two, or three infragravity–frequency components, and triad interactions solely between short-wave frequencies. In the shoaling zone, the energy transfers are generally from the spectral peak to its higher harmonics and to infragravity frequencies. While receiving net energy, infragravity waves participate in interactions that spread energy of the short-wave peaks to adjacent frequencies, thereby creating a broader energy spectrum. In the short-wave surf zone, infragravity–infragravity interactions develop, and close to shore, they dominate the interactions. Nonlinear energy fluxes are compared to gradients in total energy flux and are observed to balance nearly completely. Overall, energy losses at both infragravity and short-wave frequencies can largely be explained by a cascade of nonlinear energy transfers to high frequencies (say, f > 1.5 Hz) where the energy is presumably dissipated. Infragravity–infragravity interactions seem to induce higher harmonics that allow for shape transformation of the infragravity wave to asymmetric. The largest decrease in infragravity wave height occurs close to the shore, where infragravity–infragravity interactions dominate and where the infragravity wave is asymmetric, suggesting wave breaking to be the dominant mechanism of infragravity wave dissipation.
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Shih, Pei-Ju Rita, and Marcel Frehner. "Laboratory evidence for Krauklis-wave resonance in fractures and implications for seismic coda wave analysis." GEOPHYSICS 81, no. 6 (November 2016): T285—T293. http://dx.doi.org/10.1190/geo2016-0067.1.
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Krauklis waves are of major interest because they can lead to resonance effects in fluid-filled fractures. This resonance is marked by seismic signals with a dominant signature frequency, which may reveal fracture-related rock properties. In our laboratory study, we used homogeneous Plexiglas samples containing a single well-defined (i.e., manufactured) fracture. We recorded the signals obtained from propagating ultrasonic P- and S-waves (source frequency: 0.6, 1, and 2.25 MHz) along a sample without a fracture and samples with a fracture with different inclination angles of 30°, 45°, and 60° with respect to the short axis. The experimental results obtained from an incident S-wave confirmed that the presence of the fracture led to resonance effects at frequencies lower than the dominant source frequency, which slowly decayed over time in the recorded seismic coda after the first arrival. The resonance frequency was independent of the fracture orientation and the source frequency. We have interpreted this narrow-banded coda signal as a resonance in the fracture, and the frequency at which this occurred was an intrinsic property of the fracture size and elastic properties. To verify our laboratory results, we used an analytical solution, which provided a relationship between the fracture width, fracture length, resonance frequency, and temporal quality factor (i.e., exponential decay over time). The temporal quality factor obtained from our laboratory data agreed very well with the analytical solution. Hence, we concluded that the observed signature frequency (approximately 0.1 MHz) in the seismic coda was indeed a resonance effect. Finally, we have developed possible applications on the reservoir scale to infer fracture-related properties based on seismic coda analysis.
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Zavadsky, A., D. Liberzon, and L. Shemer. "Statistical Analysis of the Spatial Evolution of the Stationary Wind Wave Field." Journal of Physical Oceanography 43, no. 1 (January 1, 2013): 65–79. http://dx.doi.org/10.1175/jpo-d-12-0103.1.
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Abstract Detailed investigation of wind-generated water waves in a 5-m-long wind wave flume facility is reported. Careful measurements were carried out at a large number of locations along the test section and at numerous airflow rates. The evolution of the wind wave field was investigated using appropriate dimensionless parameters. When possible, quantitative comparison with the results accumulated in field measurements and in larger laboratory facilities was performed. Particular attention was given to the evolution of wave frequency spectra along the tank, distinguishing between the frequency domain around the spectral peak and the high-frequency tail of the spectrum. Notable similarity between the parameters of the evolving wind wave field in the present facility and in field measurements was observed.
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Porter, Aaron K., Merrick C. Haller, and Pukha Lenee-Bluhm. "LABORATORY OBSERVATIONS AND NUMERICAL MODELING OF THE EFFECTS OF AN ARRAY OF WAVE ENERGY CONVERTERS." Coastal Engineering Proceedings 1, no. 33 (December 15, 2012): 67. http://dx.doi.org/10.9753/icce.v33.management.67.
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This paper investigates the effects of wave energy converters (WECs) on water waves through the analysis of extensive laboratory experiments, as well as subsequent numerical simulations. Data for the analysis was collected during the WEC-Array Experiments performed at the O.H. Hinsdale Wave Research Laboratory at Oregon State University, in collaboration with Columbia Power Technologies, using five 1:33 scale point-absorbing WECs. The observed wave measurement and WEC performance data sets allowed for a direct computation of power removed from the wave field for a large suite of incident wave conditions and WEC array sizes. Using measured power absorption characteristics as a WEC parameterization for SWAN was developed. This parameterization was verified by comparison to the observational data set. Considering the complexity of the problem, the parameterization of WECs by only power absorption is a reasonable predictor of the effect of WECs on the far field.
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Osborne, A. R., and M. Petti. "Numerical inverse-scattering-transform analysis of laboratory-generated surface wave trains." Physical Review E 47, no. 2 (February 1, 1993): 1035–37. http://dx.doi.org/10.1103/physreve.47.1035.
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Hu, Chunye, Jialing Hao, and Zhen Liu. "Mean Current Profile over Rippled-Beds in the Presence of Non-Breaking Waves and Analysis of Its Influencing Factors." Journal of Marine Science and Engineering 9, no. 9 (September 8, 2021): 986. http://dx.doi.org/10.3390/jmse9090986.
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Classical eddy viscosity model deviates from the actual mean current profiles, when calculating the mean current profiles over rippled-beds in the presence of non-breaking waves, owing to the neglect of the enhancement of the wave boundary layer thickness by ripples and the wave-induced shear stress (the radiation stress and the wave Reynolds stress). Considering these shortcomings, a semi-empirical one-dimensional vertical (1DV) model is presented in this study. The present model was obtained using the two-dimensional Navier–Stokes equations and eddy viscosity assumptions, which differ from those of previous researchers, while a top-to-bottom sequence was adopted to calculate the mean current profiles. Empirical formulae were derived from the laboratory measurements and used in the present model to accurately predict the wave boundary layer thickness and bed roughness. The present model is in satisfactory agreement with the data from laboratory experiments. The factors influencing the mean current profiles were analyzed also. The wave-induced second-order shear stresses were found to be the principal reason for the deviations of the mean current profiles in the near-surface layer; as the influencing factors of wave-induced shear stress, the intensity of the wave relative to the current, the angle between the wave and current, and the size of ripples can also have a non-negligible effect on the mean current profiles.
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Latheef, M., C. Swan, and J. Spinneken. "A laboratory study of nonlinear changes in the directionality of extreme seas." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, no. 2199 (March 2017): 20160290. http://dx.doi.org/10.1098/rspa.2016.0290.
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This paper concerns the description of surface water waves, specifically nonlinear changes in the directionality. Supporting calculations are provided to establish the best method of directional wave generation, the preferred method of directional analysis and the inputs on which such a method should be based. These calculations show that a random directional method, in which the phasing, amplitude and direction of propagation of individual wave components are chosen randomly, has benefits in achieving the required ergodicity. In terms of analysis procedures, the extended maximum entropy principle, with inputs based upon vector quantities, produces the best description of directionality. With laboratory data describing the water surface elevation and the two horizontal velocity components at a single point, several steep sea states are considered. The results confirm that, as the steepness of a sea state increases, the overall directionality of the sea state reduces. More importantly, it is also shown that the largest waves become less spread or more unidirectional than the sea state as a whole. This provides an important link to earlier descriptions of deterministic wave groups produced by frequency focusing, helps to explain recent field observations and has important practical implications for the design of marine structures and vessels.
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Fedotov, A. A. "Analysis of Pulse Wave Amplitude Measurement Errors." Biomedical Engineering 54, no. 4 (November 2020): 289–93. http://dx.doi.org/10.1007/s10527-020-10024-4.
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Maciel, Rafael P., Cristiano Fragassa, Bianca N. Machado, Luiz A. O. Rocha, Elizaldo D. dos Santos, Mateus N. Gomes, and Liércio A. Isoldi. "Verification and Validation of a Methodology to Numerically Generate Waves Using Transient Discrete Data as Prescribed Velocity Boundary Condition." Journal of Marine Science and Engineering 9, no. 8 (August 19, 2021): 896. http://dx.doi.org/10.3390/jmse9080896.
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This work presents a two-dimensional numerical analysis of a wave channel and a oscillating water column (OWC) device. The main goal is to validate a methodology which uses transient velocity data as a means to impose velocity boundary condition for the generation of numerical waves. To achieve this, a numerical wave channel was simulated using regular waves with the same parameters as those used in a laboratory experiment. First, these waves were imposed as prescribed velocity boundary condition and compared with the analytical solution; then, the OWC device was inserted into the computational domain, aiming to validate this methodology. For the numerical analysis, computational fluid dynamics ANSYS Fluent software was employed, and to tackle with water–air interaction, the nonlinear multiphase model volume of fluid (VOF) was applied. Although the results obtained through the use of discrete data as velocity boundary condition presented a little disparity; in general, they showed a good agreement with laboratory experiment results. Since many studies use regular waves, there is a lack of analysis with ocean waves realistic data; thus, the proposed methodology stands out for its capacity of using realistic sea state data in numerical simulations regarding wave energy converters (WECs).
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Palma, Giuseppina, Sara Mizar Formentin, and Barbara Zanuttigh. "ANALYSIS OF THE IMPACT PROCESS AT DIKES WITH CROWN WALLS AND PARAPETS." Coastal Engineering Proceedings, no. 36v (December 31, 2020): 55. http://dx.doi.org/10.9753/icce.v36v.papers.55.
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This paper is focused on the analysis of the impact process at dikes with crown walls and parapets under breaking and non-breaking waves. A small-scale laboratory campaign was performed at the Hydraulic Laboratory of Bologna. The experiments were aimed to analyze the vertical pressure distribution along the crown wall and the resulting wave forces, by varying geometrical and hydraulic parameters. The tested configurations included different off-shore slopes, dike crest widths, crown-wall heights, dike crest freeboards and the inclusion of the parapet. The measurements were combined with the image analysis of the run-up and of the wave impact process. A sub-set of the experiments was numerically reproduced, with the openFOAM modelling suite, to support and to extend the experimental results. The results confirmed the link between the air content, the shape and the magnitude of the pressures according to the breaker type, already observed for larger-scale experiments.
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Korneev, Valeri, Ludmila Danilovskaya, Seiji Nakagawa, and George Moridis. "Krauklis wave in a trilayer." GEOPHYSICS 79, no. 4 (July 1, 2014): L33—L39. http://dx.doi.org/10.1190/geo2013-0216.1.
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The Krauklis wave is a slow dispersive wave mode that propagates in a fluid layer bounded by elastic media. The guided properties of this wave and its ability to generate very short wavelengths at seismic frequency range predict possibility of resonances in fluid-filled rock fractures. Study of Krauklis wave properties at laboratory scales requires evaluation of its propagation velocities in models with finite and thin elastic walls. Analysis of an exact solution for a fluid-filled trilayer with equal thickness plates reveals existence of the Krauklis waves in such a model, as well as another mode which propagates mostly in the solid part. Both propagation modes exist at all frequencies. We derived and verified various asymptotic solutions by comparing their dependencies on layer thicknesses and frequency with the exact numerical solution. Analytical and computational results demonstrate that in a 60-cm-long model, the first resonant frequency can be below 10 Hz. This result suggests that the Krauklis-wave effects can be studied in a laboratory at seismic range of frequencies avoiding a notorious problem of frequency downscaling. Strong dispersive properties of Krauklis waves and their dominant behavior in fluid-fracture systems are likely phenomena explaining the observed frequency-dependent seismic effects in natural underground reservoirs.
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Tian, Miao, Alex Sheremet, James M. Kaihatu, and Gangfeng Ma. "On the Shoaling of Solitary Waves in the Presence of Short Random Waves." Journal of Physical Oceanography 45, no. 3 (March 2015): 792–806. http://dx.doi.org/10.1175/jpo-d-14-0142.1.
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AbstractOverhead video from a small number of laboratory tests conducted by Kaihatu et al. at the Tsunami Wave Basin at Oregon State University shows that the breaking point of a shoaling solitary wave shifts to deeper water if random waves are present. The analysis of the laboratory data collected confirms that solitary waves indeed tend to break earlier in the presence of random wave field, and suggests that the effect is the result of the radiation stresses gradient induced by the random wave fields. A theoretical approach based on the forced KdV equation is shown to successfully predict the shoaling process of the solitary wave. An ensemble of tests simulated using a state-of-the-art nonhydrostatic model is used to test the statistical significance of the process. The results of this study point to a potentially significant oceanographic process that has so far been ignored and suggest that systematic research into the interaction between tsunami waves and the swell background could increase the accuracy of tsunami forecasting.
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Shi, He, Jinzhe Gong, Aaron C. Zecchin, Martin F. Lambert, and Angus R. Simpson. "Hydraulic transient wave separation algorithm using a dual-sensor with applications to pipeline condition assessment." Journal of Hydroinformatics 19, no. 5 (July 18, 2017): 752–65. http://dx.doi.org/10.2166/hydro.2017.146.
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Over the past two decades, techniques have been developed for pipeline leak detection and condition assessment using hydraulic transient waves (i.e. water hammer waves). A common measurement strategy for applications involves analysis of signals from a single pressure sensor located at each measurement site. The measured pressure trace from a single sensor is a superposition of reflections coming from upstream, and downstream, of the sensor. This superposition brings complexities for signal processing applications for fault detection analysis. This paper presents a wave separation algorithm, accounting for transmission dynamics, which enables the extraction of directional travelling waves by using two closely placed pressure sensors at one measurement site (referred to as a dual-sensor). Two typical transient incident pressure waves, a pulse wave and a step wave, are investigated in numerical simulations and laboratory experiments. Comparison of the wave separation results with their predicted counterparts shows the wave separation algorithm is successful. The results also show that the proposed wave separation technique facilitates transient-based pipeline condition assessment.
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Crabtree, Chris, Gurudas Ganguli, and Erik Tejero. "Analysis of self-consistent nonlinear wave-particle interactions of whistler waves in laboratory and space plasmas." Physics of Plasmas 24, no. 5 (May 2017): 056501. http://dx.doi.org/10.1063/1.4977539.
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Rapizo, Henrique, Takuji Waseda, Alexander V. Babanin, and Alessandro Toffoli. "Laboratory Experiments on the Effects of a Variable Current Field on the Spectral Geometry of Water Waves." Journal of Physical Oceanography 46, no. 9 (September 2016): 2695–717. http://dx.doi.org/10.1175/jpo-d-16-0011.1.
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AbstractLaboratory experiments were performed to investigate the effects of a coflowing current field on the spectral shape of water waves. The results indicate that refraction is the main factor in modulating wave height and overall wave energy. Although the structure of the current field varies considerably, some current-induced patterns in the wave spectrum are observed. In high frequencies, the energy cascading generated by nonlinear interactions is suppressed, and the development of a spectral tail is disturbed, as a consequence of the detuning of the four-wave resonance conditions. Furthermore, the presence of currents slows the downshifting of the spectral peak. The suppression of the high-frequency energy under the influence of currents is more prominent as the spectral steepness increases. The energy suppression is also more accentuated and long-standing along the fetch when the directional spreading of waves is sufficiently broad. This result indicates that the current-induced detuning of resonant conditions is more effective when exact resonances are the primary mechanism of nonlinear interactions than when quasi resonances prevail (directionally narrow cases). Additionally, the directional analysis shows that the highly variable currents broaden the directional spreading of waves. The broadening is suggested to be related to random refraction and scattering of wave rays. The random disturbance of wavenumbers alters the nonlinear interaction conditions and weakens the energy exchanges among wave components, which is expressed in the suppression of the high-frequency energy.
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Filipot, J. F., P. Guimaraes, F. Leckler, J. Hortsmann, R. Carrasco, E. Leroy, N. Fady, et al. "La Jument lighthouse: a real-scale laboratory for the study of giant waves and their loading on marine structures." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2155 (August 19, 2019): 20190008. http://dx.doi.org/10.1098/rsta.2019.0008.
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This paper presents results from an experiment designed to improve the understanding of the relationship between extreme breaking waves and their mechanical loading on heritage offshore lighthouses. The experiment, conducted at La Jument, an iconic French offshore lighthouse, featured several records of wave, current and structure accelerations acquired during severe storm conditions, with individual waves as high as 24 m. Data analysis focuses on a storm event marked by a strong peak in the horizontal accelerations measured inside La Jument. Thanks to stereo-video wave measurements synchronized to the acceleration record we were able to identify and describe the breaking wave responsible for this intense loading. Our observations suggest that this giant wave (19 m high) had a crest elevation high enough to directly hit the lighthouse tower, above the substructure. This paper reveals the potential for conducting ambitious field experiments from offshore lighthouses in order to collect valuable storm waves and wave loading observations. This offers a possible second service life for these heritage structures as in situ laboratories dedicated to the study of the coastal hydrodynamics and its interaction with marine structures. This article is part of the theme issue ‘Environmental loading of heritage structures’.
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Caplain, Bastien, Dominique Astruc, Vincent Regard, and Frédéric Moulin. "EXPERIMENTAL ANALYSIS OF EROSIVE COHESIVE COASTLINE MORPHOLOGY." Coastal Engineering Proceedings 1, no. 32 (January 31, 2011): 53. http://dx.doi.org/10.9753/icce.v32.sediment.53.
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Laboratory experiments have been performed in a wave flume to investigate the coastal cliff recession under regular waves forcing. The different processes of the cliff erosion cycle are described and we focus on bottom evolution, which seem mostly depend on the surf similarity parameter ξ. We observed steep planar (ξ > 0.7), gentle planar (0.5 < ξ < 0.7) and bared (ξ < 0.5) profiles. We noticed different sandbar dynamics including either steady or unsteady self-sustained oscillating states. Then we estimate the role of the self-organized material on the cliff recession rate. We show that the cliff erosion increases with the wave energy flux and is stronger for a gentle planar profile than for a bared profile of bottom morphology. However, the cliff recession rate as a function of the cliff height is not monotonic due to a different dynamics of bottom morphologies.
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Blondeaux, P., E. Foti, and G. Vittori. "A theoretical model of asymmetric wave ripples." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2033 (January 28, 2015): 20140112. http://dx.doi.org/10.1098/rsta.2014.0112.
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The time development of ripples under sea waves is investigated by means of the weakly nonlinear stability analysis of a flat sandy bottom subjected to the viscous oscillatory flow that is present in the boundary layer at the bottom of propagating sea waves. Second-order effects in the wave steepness are considered, to take into account the presence of the steady drift generated by the surface waves. Hence, the work of Vittori & Blondeaux (1990 J. Fluid Mech. 218 , 19–39 ( doi:10.1017/S002211209000091X )) is extended by considering steeper waves and/or less deep waters. As shown by the linear analysis of Blondeaux et al. (2000 Eur. J. Mech. B 19 , 285–301 ( doi:10.1016/S0997-7546(90)00106-I )), because of the presence of a steady velocity component in the direction of wave propagation, ripples migrate at a constant rate that depends on sediment and wave characteristics. The weakly nonlinear analysis shows that the ripple profile is no longer symmetric with respect to ripple crests and troughs and the symmetry index is computed as a function of the parameters of the problem. In particular, a relationship is determined between the symmetry index and the strength of the steady drift. A fair agreement between model results and laboratory data is obtained, albeit further data and analyses are necessary to determine the behaviour of vortex ripples and to be conclusive.
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Favretto-Cristini, Nathalie, Arkady M. Aizenberg, Bjørn Ursin, Paul Cristini, and Anastasiya Tantsereva. "Analysis of Wave Scattering from a Viscoelastic Layer with Complex Shape." Journal of Computational Acoustics 25, no. 03 (September 2017): 1750023. http://dx.doi.org/10.1142/s0218396x17500230.
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The Discretized Kirchhoff Integral method has been recently tested against laboratory experiments using a model with surface curvatures and sharp edges generating wave diffraction effects. Comparisons between numerical and laboratory data have exhibited a good quantitative fit in terms of time arrivals and amplitudes, except in the vicinity of secondary shadow boundaries created by the interaction of the edges of some topographical structures. Following this work, the effect of multiple scattering and the surface curvatures on the wavefield is studied here, using the so-called diffraction attenuation coefficient, in order to define the cases where these effects may be neglected in the numerical modeling without loss of accuracy.
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KÂNOĞLU, UTKU, and COSTAS EMMANUEL SYNOLAKIS. "Long wave runup on piecewise linear topographies." Journal of Fluid Mechanics 374 (November 10, 1998): 1–28. http://dx.doi.org/10.1017/s0022112098002468.
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We study long-wave evolution and runup on piecewise linear one- and two-dimensional bathymetries analytically and experimentally with the objective of understanding certain coastal effects of tidal waves. We develop a general solution method for determining the amplification factor of different ocean topographies consisting of linearly varying and constant-depth segments to study how spectral distributions evolve over bathymetry, and apply our results to study the evolution of solitary waves. We find asymptotic results which suggest that solitary waves often interact with piecewise linear topographies in a counter-intuitive manner. We compare our analytical predictions with numerical results, with results from a new set of laboratory experiments from a physical model of Revere Beach, and also with the data on wave runup around an idealized conical island. We find good agreement between our theory and the laboratory results for the time histories of free-surface elevations and for the maximum runup heights. Our results suggest that, at least for simple piecewise linear topographies, analytical methods can be used to calculate effectively some important physical parameters in long-wave runup. Also, by underscoring the effects of the topographic slope at the shoreline, this analysis qualitatively suggests why sometimes predictions of field-applicable numerical models differ substantially from observations of tsunami runup.
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Herman, Agnieszka, Sukun Cheng, and Hayley H. Shen. "Wave energy attenuation in fields of colliding ice floes – Part 2: A laboratory case study." Cryosphere 13, no. 11 (November 8, 2019): 2901–14. http://dx.doi.org/10.5194/tc-13-2901-2019.
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Abstract. This work analyses laboratory observations of wave energy attenuation in fragmented sea ice cover composed of interacting, colliding floes. The experiment, performed in a large (72 m long) ice tank, includes several groups of tests in which regular, unidirectional, small-amplitude waves of different periods were run through floating ice with different floe sizes. The vertical deflection of the ice was measured at several locations along the tank, and video recording was used to document the overall ice behaviour, including the presence of collisions and overwash of the ice surface. The observational data are analysed in combination with the results of two types of models: a model of wave scattering by a series of floating elastic plates, based on the matched eigenfunction expansion method (MEEM), and a coupled wave–ice model, based on discrete-element model (DEM) of sea ice and a wave model solving the stationary energy transport equation with two source terms, describing dissipation due to ice–water drag and due to overwash. The observed attenuation rates are significantly larger than those predicted by the MEEM model, indicating substantial contribution from dissipative processes. Moreover, the dissipation is frequency dependent, although, as we demonstrate in the example of two alternative theoretical attenuation curves, the quantitative nature of that dependence is difficult to determine and very sensitive to assumptions underlying the analysis. Similarly, more than one combination of the parameters of the coupled DEM–wave model (restitution coefficient, drag coefficient and overwash criteria) produce spatial attenuation patterns in good agreement with observed ones over a range of wave periods and floe sizes, making selection of “optimal” model settings difficult. The results demonstrate that experiments aimed at identifying dissipative processes accompanying wave propagation in sea ice and quantifying the contribution of those processes to the overall attenuation require simultaneous measurements of many processes over possibly large spatial domains.
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Sutherland, Bruce R. "The wave instability pathway to turbulence." Journal of Fluid Mechanics 724 (April 29, 2013): 1–4. http://dx.doi.org/10.1017/jfm.2013.149.
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AbstractOne way that large-scale oceanic internal waves transfer their energy to small-scale mixing is through parametric subharmonic instability (PSI). But there is a disconnect between theory, which assumes the waves are periodic in space and time, and reality, in which waves are transient and localized. The innovative laboratory experiments and analysis techniques of Bourget et al. (J. Fluid Mech., vol. 723, 2013, pp. 1–20) show that theory can be applied to interpret the generation of subharmonic disturbances from a quasi-monochromatic wave beam. Their methodology and results open up new avenues of investigation into PSI through experiments, simulations and observations.
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Rabault, Jean, Graig Sutherland, Atle Jensen, Kai H. Christensen, and Aleksey Marchenko. "Experiments on wave propagation in grease ice: combined wave gauges and particle image velocimetry measurements." Journal of Fluid Mechanics 864 (February 13, 2019): 876–98. http://dx.doi.org/10.1017/jfm.2019.16.
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Water wave attenuation by grease ice is a key mechanism for the polar regions, as waves in ice influence many phenomena such as ice drift, ice breaking and ice formation. However, the models presented so far in the literature are limited in a number of regards, and more insights are required from either laboratory experiments or fieldwork for these models to be validated and improved. Unfortunately, performing detailed measurements of wave propagation in grease ice, either in the field or in the laboratory, is challenging. As a consequence, laboratory data are relatively scarce, and often consist of only a couple of wave elevation measurements along the length of the wave tank. We present combined measurements of wave elevation using an array of ultrasonic probes, and water kinematics using particle image velocimetry (PIV), in a small-scale wave tank experiment. Experiments are performed over a wider frequency range than has been previously investigated. The wave elevation measurements are used to compute the wavenumber and exponential damping coefficient. In contrast to a previous study in grease ice, we find that the wavenumber is consistent with the mass loading model, i.e. it increases compared with the open water case. Wave attenuation is compared with a series of one-layer models, and we show that they satisfactorily describe the viscous damping occurring. PIV data are also consistent with exponential wave amplitude attenuation, and a proper orthogonal decomposition analysis reveals the existence of mean flows under the ice that are a consequence of the displacement and packing of the ice induced by the gradient in the wave-induced stress. Finally, we show that the dynamics of grease ice can generate eddy structures that inject eddy viscosity into the water under the grease ice, which would lead to enhanced mixing and participating in energy dissipation.
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Maulidah, Shopi Setiawati, and Eka Cahya Prima. "Using Physics Education Technology as Virtual Laboratory in Learning Waves and Sounds." Journal of Science Learning 1, no. 3 (July 31, 2018): 116. http://dx.doi.org/10.17509/jsl.v1i3.11797.
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This research was intended to analyze the use of Physics Education Technology (PhET) as a virtual laboratory in learning waves and sounds. The analysis was in terms of the implementation of waves on a string student activity as a lesson plan, the profile of students’ cognitive, and the profile of science laboratory environment. The method which is used in this research was a descriptive method with methodological triangulation as the research design. The sample was taken on the convenient situation at grade 8 in an international school in Bandung. According to the analysis of the result, the waves on a string student activity can be adopted as the lesson plan with several recommendation to be improved such as in part A, changing some sentences in the data table, changing some settings in obtaining data activity, and adding clear example in determining the base and peak point in measuring the height of wave at start and at the end. Moreover in part B, adding clear instruction on how to use the ruler to measure the wavelength, and changing the picture to obtain the data of wavelength with the picture of simulation with the instructed setting are important. In part C, it needs to add the instruction to do the practice session together with the teacher and to add the instruction to make the starting point in counting the wave similar in each trial. The use of Physics Education Technology (PhET) as a virtual laboratory in learning waves and sounds shows the favorable result on both the cognitive aspect and science laboratory environment.
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Bokhove, Onno, Anna Kalogirou, David Henry, and Gareth P. Thomas. "A novel wave-energy device with enhanced wave amplification and induction actuator." International Marine Energy Journal 3, no. 1 (May 14, 2020): 37–44. http://dx.doi.org/10.36688/imej.3.37-44.
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A novel wave-energy device is presented. Both a preliminary proof-of-principle of a working, scaled laboratory version of the energy device is shown as well as the derivation and analysis of a comprehensive mathematical and numerical model of the new device. The wave-energy device includes a convergence in which the waves are amplified, a constrained wave buoy with a (curved) mast and direct energy conversion of the buoy motion into electrical power via an electro-magnetic generator. The device is designed for use in breakwaters and it is possible to be taken out of action during severe weather. The new design is a deconstruction of elements of existing wave-energy devices, such as the TapChan, IP wave-buoy and the Berkeley Wedge, put together in a different manner to enhance energy conversion and, hence, efficiency. The idea of wave-focusing in a contraction emerged from our work on creating and simulating rogue waves in crossing seas, including a "bore-soliton-splash". Such crossing seas have been recreated and modelled in the laboratory and in simulations by using a geometric channel convergence. The mathematical and numerical modelling is also novel. One monolithic variational principle governs the dynamics including the combined (potential-flow) hydrodynamics, the buoy motion and the power generation, to which the dissipative elements such as the electrical resistance of the circuits, coils and loads have been added a posteriori. The numerical model is a direct and consistent discretisation of this comprehensive variational principle. Preliminary numerical calculations are shown for the case of linearised dynamics; optimisation of efficiency is a target of future work.
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Huang, Zhenhua, and Zhida Yuan. "Transmission of solitary waves through slotted barriers: A laboratory study with analysis by a long wave approximation." Journal of Hydro-environment Research 3, no. 4 (March 2010): 179–85. http://dx.doi.org/10.1016/j.jher.2009.10.009.
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Li, Meng-Syue, Cheng-Jung Hsu, Hung-Chu Hsu, and Li-Hung Tsai. "Numerical Analysis of Vertical Breakwater Stability under Extreme Waves." Journal of Marine Science and Engineering 8, no. 12 (December 3, 2020): 986. http://dx.doi.org/10.3390/jmse8120986.
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The purpose of this study is to perform a numerical simulation of caisson breakwater stability concerning the effect of wave overtopping under extreme waves. A numerical model, which solves two-dimensional Reynolds-averaged Navier–Stokes equations with the k−ε turbulence closure and uses the volume of fluid method for surface capturing, is validated with the laboratory observations. The numerical model is shown to accurately predict the measured free-surface profiles and the wave pressures around a caisson breakwater. Considering the dynamic loading on caisson breakwaters during overtopping waves, not only landward force and lift force but also the seaward force are calculated. Model results suggest that the forces induced by the wave overtopping on the back side of vertical breakwater and the phase lag of surface elevations have to be considered for calculating the breakwater stability. The numerical results also show that the failure of sliding is more dangerous than the failure of overturning in the vertical breakwater. Under extreme waves with more than 100 year return period, the caisson breakwater is sliding unstable, whereas it is safe in overturning stability. The influence of wave overtopping on the stability analysis is dominated by the force on the rear side of the caisson and the phase difference on the two ends of caisson. For the case of extreme conditions, if the impulse force happens at the moment of the minimum of load in the rear side, the safety factor might decrease significantly and the failure of sliding might cause breakwater damage. This paper demonstrates the potential stability failure of coastal structures under extreme sea states and provides adapted formulations of safety factors in dynamic form to involve the influence of overtopping waves.
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Cienfuegos, Rodrigo, L. Duarte, L. Suarez, and P. A. Catalán. "NUMERICAL COMPUTATION OF INFRAGRAVITY WAVE DYNAMICS AND VELOCITY PROFILES USING A FULLY NONLINEAR BOUSSINESQ MODEL." Coastal Engineering Proceedings 1, no. 32 (January 29, 2011): 48. http://dx.doi.org/10.9753/icce.v32.currents.48.
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We present experimental and numerical analysis of nonlinear processes responsible for generating infragravity waves
in the nearshore. We provide new experimental data on random wave propagation and associated velocity profiles in
the shoaling and surf zones of a very mild slope beach. We analyze low frequency wave generation mechanisms and
dynamics along the beach and examine in detail the ability of the fully nonlinear Boussinesq- type model SERR1D
(Cienfuegos et al., 2010) to reproduce the complex dynamics of high frequency wave propagation and energy transfer
mechanisms that enhance infragravity wave generation in the laboratory.
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Kosyan, R. D., and B. V. Divinsky. "PROBLEMS OF SEDIMENTS TRANSPORT MODELING IN THE COASTAL AREA." Journal of Oceanological Research 49, no. 1 (April 26, 2021): 93–141. http://dx.doi.org/10.29006/1564-2291.jor-2021.49(1).6.
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Due to the development of measuring instruments, a more detailed analysis of the wave field and the field of suspended sediments spatio-temporal characteristics has become possible. Through the efforts of Russian specialists over the past decades: A unique database of observations of the sediment movement in storm situations in different physical and geographical areas of the coastal zone of the Black, Baltic, North, Mediterranean, South China Seas has been collected, supplemented by extensive data of laboratory experiments in the best laboratory in Europe (Hannover, Germany). New experimental material has been obtained to determine the physical features of sediment transport by wave flow. The main mechanisms controlling the amplitude and phase relationships of the concentration fluctuations and discharge of suspended sediment on time scales less than the period of the peak of the wind wave spectrum are considered. The presence of low-frequency fluctuations in sediment concentration with a period of the order of several periods of wind waves and an amplitude several times higher than the average value of concentration is noted. The previously unexplored problem of the wave energy frequency distribution in the spectrum of surface waves influence on the sediment transport has been analyzed. Differences in the response of the washed-out bottom to an external disturbance, represented by irregular surface waves with constant integral characteristics (significant wave height and period of the spectrum peak) and variable wave energy frequency distribution, were revealed. The influence of swell waves on the redistribution of bottom sediments in the sea coastal zone was investigated. It is shown that dividing the wave field into separate components allows a more correct description of the spatiotemporal structure of surface waves, as well as a significant refinement of the bottom sediment transport schemes in the coastal zone. Using the example of the Anapa bay bar, it is shown that situations are possible in which the alongshore flow of bottom sediments is almost completely determined by swell waves. The results of field and laboratory experiments make it possible to determine the directions for further research on the creation of physically based models of sediment transport by waves and wave currents.
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Fedotov, A. A. "Techniques for the Morphological Analysis of the Pulse Wave." Biomedical Engineering 53, no. 4 (November 2019): 270–74. http://dx.doi.org/10.1007/s10527-019-09924-x.
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Sulisz, Wojciech, and Maciej Paprota. "Theoretical and Experimental Investigations of Wave-Induced Vertical Mixing." Mathematical Problems in Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/950849.
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Theoretical investigations supported by a series of original laboratory experiments are conducted to study a wave-induced vertical mixing process. The derived semi-analytical solution is very efficient and is applied to predict the effects of water waves on the temperature changes and the evolution of temperature profiles. The results indicate that waves increase a mixing process. The rate of change of the temperature is higher when waves contributed to mixing process and this process increases with increasing the wavelength to water depth ratio. The analysis indicates that for typical ocean waves the contribution of water waves to mixing may be several orders of magnitude higher than a corresponding contribution arising from the classical diffusion process. This implies a need to conduct more theoretical studies and experimental investigation on the effect of water waves on mixing processes. A series of original laboratory experiments were conducted in the insulated wave flume to verify the derived model. The comparisons show a reasonable agreement between predicted and measured temperature profiles. A reasonable agreement between theoretical results and experimental data is observed for the whole considered range of initial temperature distributions. The comparisons indicate that the model is applicable even to cases when gradients in temperature distributions over water depth are fairly high.
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Muchtar, Masjono, Salama Manjang, Dadang A. Suriamiharja, and M. Arsyad Thaha. "Kinerja Model Fisik Konverter Energi Ombak Rangkaian Gear Searah pada Periode Ombak yang Bervariasi." MEDIA KOMUNIKASI TEKNIK SIPIL 22, no. 2 (December 27, 2016): 71. http://dx.doi.org/10.14710/mkts.v22i2.12871.
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To date there were few research on the effect of non-linearity properties of the ocean waves on the performance of wave energy converter (WEC), which uses a series of unidirectional gear. One such parameter is the variation of wave period. The influence of wave period variations on the performance of physical model of the wave energy converters have been investigated at the Hydraulics Laboratory, Department of Civil Engineering, Hasanuddin University Indonesia. This WEC physical model was fabricated and assembled at Politeknik ATI Makassar Indonesia. The investigation steps consists of physical model development, physical model investigation at wave flume prior to the wave period variation, measuring input output parameters of the physical model under test and empirical model formulation based on observed data analysis. Physical model test carried out on the wave flume at the Hydraulics Laboratory of the Department of Civil Hasanuddin University, at a water depth of 25 cm, wave height between 5-9 cm and wave period between 1.2 - 2.2 seconds. Investigation result based on flywheel radial speed (RPM) and torque (Nm) indicated that calculated harvested power was inversely proportional with the wave period. The longer the period of the waves, the energy produced is getting smaller. The derived empirical formula was y = -85.598x + 208.53 and R² = 0.8881. Y is energy produced (Watt) and X is the wave period (Second). Formulations generated from this study could be used as a reference for future research in dealing with wave period variations on a design one way gear wave energy converter as a source of renewable energy.
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Giovanangeli, J. P., C. Kharif, and Y. A. Stepanyants. "Soliton spectra of random water waves in shallow basins." Mathematical Modelling of Natural Phenomena 13, no. 4 (2018): 40. http://dx.doi.org/10.1051/mmnp/2018018.
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Interpretation of random wave field on a shallow water in terms of Fourier spectra is not adequate, when wave amplitudes are not infinitesimally small. A nonlinearity of wave fields leads to the harmonic interactions and random variation of Fourier spectra. As has been shown by Osborne and his co-authors, a more adequate analysis can be performed in terms of nonlinear modes representing cnoidal waves; a spectrum of such modes remains unchanged even in the process of nonlinear mode interactions. Here we show that there is an alternative and more simple analysis of random wave fields on shallow water, which can be presented in terms of interacting Korteweg–de Vries solitons. The data processing of random wave field is developed on the basis of inverse scattering method. The soliton component obscured in a random wave field is determined and a corresponding distribution function of number of solitons on their amplitudes is constructed. The approach developed is illustrated by means of artificially generated quasi-random wave field and applied to the real data interpretation of wind waves generated in the laboratory wind tank.
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Waseda, Takuji, Takeshi Kinoshita, and Hitoshi Tamura. "Evolution of a Random Directional Wave and Freak Wave Occurrence." Journal of Physical Oceanography 39, no. 3 (March 1, 2009): 621–39. http://dx.doi.org/10.1175/2008jpo4031.1.
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Abstract The evolution of a random directional wave in deep water was studied in a laboratory wave tank (50 m long, 10 m wide, 5 m deep) utilizing a directional wave generator. A number of experiments were conducted, changing the various spectral parameters (wave steepness 0.05 < ɛ < 0.11, with directional spreading up to 36° and frequency bandwidth 0.2 < δk/k < 0.6). The wave evolution was studied by an array of wave wires distributed down the tank. As the spectral parameters were altered, the wave height statistics change. Without any wave directionality, the occurrence of waves exceeding twice the significant wave height (the freak wave) increases as the frequency bandwidth narrows and steepness increases, due to quasi-resonant wave–wave interaction. However, the probability of an extreme wave rapidly reduces as the directional bandwidth broadens. The effective Benjamin–Feir index (BFIeff) is introduced, extending the BFI (the relative magnitude of nonlinearity and dispersion) to incorporate the effect of directionality, and successfully parameterizes the observed occurrence of freak waves in the tank. Analysis of the high-resolution hindcast wave field of the northwest Pacific reveals that such a directionally confined wind sea with high extreme wave probability is rare and corresponds mostly to a swell–wind sea mixed condition. Therefore, extreme wave occurrence in the sea as a result of quasi-resonant wave–wave interaction is a rare event that occurs only when the wind sea directionality is extremely narrow.
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Almar, Rafael, Rodrigo Cienfuegos, Eduardo Gonzalez, Patricio Catalán, Hervé Michallet, Philippe Bonneton, Bruno Castelle, and Leandro Suarez. "BARRED-BEACH MORPHOLOGICAL CONTROL ON INFRAGRAVITY MOTION." Coastal Engineering Proceedings 1, no. 33 (October 25, 2012): 24. http://dx.doi.org/10.9753/icce.v33.currents.24.
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A conceptual analysis of the coupling between bars and infragravity waves is performed combining laboratory experiments and numerical modeling. Experiments are carried out in a wave flume with a barred profile. The Boussinesq fully-nonlinear model SERR1D is validated with the laboratory data and a sensitivity analysis is performed next to study the influence on the infragravity wave dynamics of bar amplitude and location, and swash zone slope. A novel technique of incident and reflected motions separation that conserves temporal characteristics is applied. We observe that changing bar characteristics induces substantial variations in trapped energy. Interestingly, a modification of swash zone slope has a large influence on the reflected component, controlling amplitude and phase time-lag, and consequently on the resonant pattern. Variations of trapped infragravity energy induced by changes of swash zone slope reach 25 %. These changes in infragravity pattern consequently affect short-wave dynamics by modifying the breakpoint location and the breaking intensity. Our conceptual investigation suggests the existence of a morphological feedback through the action of evolving morphology on infragravity structures which modulates the action of short-waves on the morphology itself.
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Aranguiz, Rafael, Oscar Link, Jose Aliaga, Oscar Briones, Ruben Alarcon, and Nicolas Gatica. "ANALYSIS OF TSUNAMI SCOUR AROUND SQUARE STRUCTURES USING A PUMP-DRIVEN FLOW METHOD." Coastal Engineering Proceedings, no. 36v (December 28, 2020): 8. http://dx.doi.org/10.9753/icce.v36v.sediment.8.
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Estimation of the maximum scour depth is important for defining the size and depth of building foundations in order to avoid failure during a tsunami event (Jayaratne, et al 2016). Traditionally, tsunami scour has been studied in laboratory experiments that use solitary waves. However, it has been demonstrated that this type of wave does not represent well a real tsunami (Madsen et al, 2008). In addition, results from field surveys are based on the scour depth after the tsunami event, studying only the maximum flow depth, and ignoring other hydrodynamic features such as velocity and wave period, as well as sediment deposition. The main objective of this research is to estimate maximum tsunami scour around rectangular structures as a function of realistic tsunami variables.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/ykb-JyL7lsE
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Petrova, P. G., and C. Guedes Soares. "Distributions of nonlinear wave amplitudes and heights from laboratory generated following and crossing bimodal seas." Natural Hazards and Earth System Sciences 14, no. 5 (May 21, 2014): 1207–22. http://dx.doi.org/10.5194/nhess-14-1207-2014.
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Abstract. This paper presents an analysis of the distributions of nonlinear crests, troughs and heights of deep water waves from mixed following sea states generated mechanically in an offshore basin and compares with previous results for mixed crossing seas from the same experiment. The random signals at the wavemaker in both types of mixed seas are characterized by bimodal spectra following the model of Guedes Soares (1984). In agreement with the Benjamin–Feir mechanism, the high-frequency spectrum shows a decrease in the peak magnitude and downshift of the peak with the distance, as well as reduction of the tail. The observed statistics and probabilistic distributions exhibit, in general, increasing effects of third-order nonlinearity with the distance from the wavemaker. However, this effect is less pronounced in the wave systems with two following wave trains than in the crossing seas, given that they have identical initial characteristics of the bimodal spectra. The relevance of third-order effects due to free modes only is demonstrated and assessed by excluding the vertically asymmetric distortions induced by bound wave effects of second and third order. The fact that for records characterized by relatively large coefficient of kurtosis, the empirical distributions for the non-skewed profiles continue deviating from the linear predictions, corroborate the relevance of free wave interactions and thus the need of using higher-order models for the description of wave data.