Articoli di riviste: "Wave models"

1

Verao Fernandez, Gael, Vasiliki Stratigaki, Panagiotis Vasarmidis, Philip Balitsky e Peter Troch. "Wake Effect Assessment in Long- and Short-Crested Seas of Heaving-Point Absorber and Oscillating Wave Surge WEC Arrays". Water 11, n. 6 (29 maggio 2019): 1126. http://dx.doi.org/10.3390/w11061126.

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In the recent years, the potential impact of wave energy converter (WEC) arrays on the surrounding wave field has been studied using both phase-averaging and phase-resolving wave propagation models. Obtaining understanding of this impact is important because it may affect other users in the sea or on the coastline. However, in these models a parametrization of the WEC power absorption is often adopted. This may lead to an overestimation or underestimation of the overall WEC array power absorption, and thus to an unrealistic estimation of the potential WEC array impact. WEC array power absorption is a result of energy extraction from the incoming waves, and thus wave height decrease is generally observed downwave at large distances (the so-called “wake” or “far-field” effects). Moreover, the power absorption depends on the mutual interactions between the WECs of an array (the so-called “near field” effects). To deal with the limitations posed by wave propagation models, coupled models of recent years, which are nesting wave-structure interaction solvers into wave propagation models, have been used. Wave-structure interaction solvers can generally provide detailed hydrodynamic information around the WECs and a more realistic representation of wave power absorption. Coupled models have shown a lower WEC array impact in terms of wake effects compared to wave propagation models. However, all studies to date in which coupled models are employed have been performed using idealized long-crested waves. Ocean waves propagate with a certain directional spreading that affects the redistribution of wave energy in the lee of WEC arrays, and thus gaining insight wake effect for irregular short-crested sea states is crucial. In our research, a new methodology is introduced for the assessment of WEC array wake effects for realistic sea states. A coupled model is developed between the wave-structure interaction solver NEMOH and the wave propagation model MILDwave. A parametric study is performed showing a comparison between WEC array wake effects for regular, long-crested irregular, and short-crested irregular waves. For this investigation, a nine heaving-point absorber array is used for which the wave height reduction is found to be up to 8% lower at 1.0 km downwave the WEC array when changing from long-crested to short-crested irregular waves. Also, an oscillating wave surge WEC array is simulated and the overestimation of the wake effects in this case is up to 5%. These differences in wake effects between different wave types indicates the need to consider short-crested irregular waves to avoid overestimating the WEC array potential impacts. The MILDwave-NEMOH coupled model has proven to be a reliable numerical tool, with an efficient computational effort for simulating the wake effects of two different WEC arrays under the action of a range of different sea states.

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Zhang, Huichen, e Markus BrÃ¼hl. "GENERATION OF EXTREME TRANSIENT WAVES IN EXPERIMENTAL MODELS". Coastal Engineering Proceedings, n. 36 (30 dicembre 2018): 51. http://dx.doi.org/10.9753/icce.v36.waves.51.

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The transfer of natural waves and sea states into small- and large-scale model teste contributes to the proper design of offshore and coastal structure. Such shallow-water ocean surface waves are highly nonlinear and subject to wave transformation and nonlinear wave-wave interactions. However, the standard methods of wave generation according to conventional wave theories and wave analysis methods are limited to simple regular waves, simple sea states and low-order wave generation without considering the nonlinear wave-wave interactions. The research project Generation of Extreme Transient Waves in Experimental Models (ExTraWaG) aims to accurately generate target transient wave profile at a pre-defined position in the wave flume (transfer point) under shallow water conditions. For this purpose, the KdV-based nonlinear Fourier transform is introduced as a continuative wave analysis method and is applied to investigate the nonlinear spectral character of experimental wave data. Furthermore, the method is applied to generate transient nonlinear waves as specific locations in the wave flume, considering the nonlinear transformation and interactions of the propagating waves.

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BAL, GUILLAUME, e OLIVIER PINAUD. "IMAGING USING TRANSPORT MODELS FOR WAVE–WAVE CORRELATIONS". Mathematical Models and Methods in Applied Sciences 21, n. 05 (maggio 2011): 1071–93. http://dx.doi.org/10.1142/s0218202511005258.

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We consider the imaging of objects buried in unknown heterogeneous media. The medium is probed by using classical (e.g. acoustic or electromagnetic) waves. When heterogeneities in the medium become too strong, inversion methodologies based on a microscopic description of wave propagation (e.g. a wave equation or Maxwell's equations) become strongly dependent on the unknown details of the heterogeneous medium. In some situations, it is preferable to use a macroscopic model for a quantity that is quadratic in the wave fields. Here, such macroscopic models take the form of radiative transfer equations also referred to as transport equations. They can model either the energy density of the propagating wave fields or more generally the correlation of two wave fields propagating in possibly different media. In particular, we consider the correlation of the two fields propagating in the heterogeneous medium when the inclusion is absent and present, respectively. We present theoretical and numerical results showing that reconstructions based on this correlation are more accurate than reconstructions based on measurements of the energy density.

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Zappa, Giuseppe, Valerio Lucarini e Antonio Navarra. "Baroclinic Stationary Waves in Aquaplanet Models". Journal of the Atmospheric Sciences 68, n. 5 (1 maggio 2011): 1023–40. http://dx.doi.org/10.1175/2011jas3573.1.

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Abstract An aquaplanet model is used to study the nature of the highly persistent low-frequency waves that have been observed in models forced by zonally symmetric boundary conditions. Using the Hayashi spectral analysis of the extratropical waves, the authors find that a quasi-stationary wave 5 belongs to a wave packet obeying a well-defined dispersion relation with eastward group velocity. The components of the dispersion relation with k ≥ 5 baroclinically convert eddy available potential energy into eddy kinetic energy, whereas those with k < 5 are baroclinically neutral. In agreement with Green’s model of baroclinic instability, wave 5 is weakly unstable, and the inverse energy cascade, which had been previously proposed as a main forcing for this type of wave, only acts as a positive feedback on its predominantly baroclinic energetics. The quasi-stationary wave is reinforced by a phase lock to an analogous pattern in the tropical convection, which provides further amplification to the wave. It is also found that the Pedlosky bounds on the phase speed of unstable waves provide guidance in explaining the latitudinal structure of the energy conversion, which is shown to be more enhanced where the zonal westerly surface wind is weaker. The wave’s energy is then trapped in the waveguide created by the upper tropospheric jet stream. In agreement with Green’s theory, as the equator-to-pole SST difference is reduced, the stationary marginally stable component shifts toward higher wavenumbers, while wave 5 becomes neutral and westward propagating. Some properties of the aquaplanet quasi-stationary waves are found to be in interesting agreement with a low frequency wave observed by Salby during December–February in the Southern Hemisphere so that this perspective on low frequency variability, apart from its value in terms of basic geophysical fluid dynamics, might be of specific interest for studying the earth’s atmosphere.

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5

Dalrymple, Robert A., e James T. Kirby. "Models for very wide-angle water waves and wave diffraction". Journal of Fluid Mechanics 192 (luglio 1988): 33–50. http://dx.doi.org/10.1017/s0022112088001776.

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For a bathymetry consisting of parallel bottom contours, wide-angle parabolic models are developed to describe the diffraction of linear water waves. The first model, developed by operator correspondence, extends the validity of conventional forms of the parabolic model for wave angles up to 70° from the assumed wave direction. Through the use of Fourier decomposition, wave models valid to 90° are developed for three different lateral boundary conditions. By application, it is shown that the diffraction of waves through gaps or around structures is governed by the initial wave condition at the structure, which can be expanded into progressive and evanescent wave modes. Away from the structure, the wave field consists of only the progressive wave modes, which disperse according to their direction of propagation, the water depth and Snell's Law. Examples are shown for oblique waves through a gap, directional seas past a breakwater, a plane wave with varying crest amplitude, and finally for the diffraction of waves into a channel.

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6

Geller, Marvin A., Tiehan Zhou, Reto Ruedy, Igor Aleinov, Larissa Nazarenko, Nikolai L. Tausnev, Shan Sun, Maxwell Kelley e Ye Cheng. "New Gravity Wave Treatments for GISS Climate Models". Journal of Climate 24, n. 15 (1 agosto 2011): 3989–4002. http://dx.doi.org/10.1175/2011jcli4013.1.

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Abstract Previous versions of GISS climate models have either used formulations of Rayleigh drag to represent unresolved gravity wave interactions with the model-resolved flow or have included a rather complicated treatment of unresolved gravity waves that, while being climate interactive, involved the specification of a relatively large number of parameters that were not well constrained by observations and also was computationally very expensive. Here, the authors introduce a relatively simple and computationally efficient specification of unresolved orographic and nonorographic gravity waves and their interaction with the resolved flow. Comparisons of the GISS model winds and temperatures with no gravity wave parameterization; with only orographic gravity wave parameterization; and with both orographic and nonorographic gravity wave parameterizations are shown to illustrate how the zonal mean winds and temperatures converge toward observations. The authors also show that the specifications of orographic and nonorographic gravity waves must be different in the Northern and Southern Hemispheres. Then results are presented where the nonorographic gravity wave sources are specified to represent sources from convection in the intertropical convergence zone and spontaneous emission from jet imbalances. Finally, a strategy to include these effects in a climate-dependent manner is suggested.

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7

Pruser, H. H., H. Schaper e W. Zielke. "IRREGULAR WAVE TRANSFORMATION IN A BOUSSINESO WAVE MODEL". Coastal Engineering Proceedings 1, n. 20 (29 gennaio 1986): 205. http://dx.doi.org/10.9753/icce.v20.205.

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Numerical wave models for shallow water waves are of particular importance for the calculation of the wave climate in harbours and coastal areas. Especially nonlinear time domain models, which are based on the Boussinesq-Wave- Equations, may be helpful in the future for simulating the interaction of currents with refraction, diffraction, reflection and for simulating shoaling..-of irregular waves in natural areas; a potential which has not yet been fully developed. During the last ten years numerical models, based on these equations, have been published; such as ABBOTT et. al. , HAUGUEL and SCHAPER / ZIELKE . Research on this topic is currently being carried on. Some efforts have been made to verify the capability of the models to describe the various physical phenomena. However, up to now, verification has been limited to regular waves. The aim of this paper therefore is, to consider questions concerning irregular, nonlinear waves.

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8

Ito, Masahiro, e Yoshito Tsuchiya. "REPRODUCTION MODELS OF BEACH CHANGE BY STORM WAVES". Coastal Engineering Proceedings 1, n. 21 (29 gennaio 1988): 115. http://dx.doi.org/10.9753/icce.v21.115.

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This paper presents a technique to reproduce, by a twodimensional moveable-bed model, beach change due to the timedependent storm waves which are generated by the passage of an atmospheric depression. In the model test, scaling conditions for sand grain-size, vertical and horizontal lengths, and wave height and period characteristics were established by applying the authors' scale-model relationship which was reported; and wave duration time also was decided. A method of employing regular waves in the model to represent irregular waves in the field is proposed. From the results, it was shown that the model can reproduce well the beach change in the field using the regular waves having the mean wave properties in the irregular waves.

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9

Kichenassamy, Satyanad. "Existence of solitary waves for water-wave models". Nonlinearity 10, n. 1 (1 gennaio 1997): 133–51. http://dx.doi.org/10.1088/0951-7715/10/1/009.

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10

Niedzwecki, John M., Eric W. Sandt e Oriol R. Rijken. "Slepian models for waves and wave-structure interaction". Engineering Structures 17, n. 10 (dicembre 1995): 696–704. http://dx.doi.org/10.1016/0141-0296(95)00060-k.

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11

Estrade, Anne, e Julie Fournier. "Anisotropic Gaussian wave models". Latin American Journal of Probability and Mathematical Statistics 17, n. 1 (2020): 329. http://dx.doi.org/10.30757/alea.v17-13.

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12

Griffin, Daniel J., e John Thuburn. "Numerical Effects on Wave Propagation in Atmospheric Models". Proceedings of the International Astronomical Union 13, S335 (luglio 2017): 288–90. http://dx.doi.org/10.1017/s1743921317007979.

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AbstractRay tracing techniques have been used to investigate numerical effects on the propagation of acoustic waves in a non-hydrostatic dynamical core discretised using an Arakawa C-grid horizontal staggering of variables (Arakawa & Lamb 1977) and a Charney-Phillips vertical staggering of variables (Charney & Phillips 1953) with a semi-implicit timestepping scheme. It is found that the space discretisation places limits on resolvable wavenumbers and redirects the group velocity of waves towards the vertical. Wave amplitudes grow exponentially with height due to the decrease in the background density, which can cause instabilities in whole-atmosphere models. However, the inclusion of molecular viscosity and diffusion acts to damp the exponential growth of waves above about 150 km. This study aims to demonstrate the extent to which numerical wave propagation causes instabilities at high altitudes in atmosphere models, and how processes that damp the waves can improve these model’s stability.

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13

Zhang, Jun. "Hybrid Wave Models and Their Applications for Steep Ocean Waves". Marine Technology Society Journal 33, n. 3 (1 gennaio 1999): 15–26. http://dx.doi.org/10.4031/mtsj.33.3.3.

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Bound-wave components resulting from inter-actions among free-wave components have significant effects on resultant wave properties, especially in a steep ocean wave field. Hybrid Wave Models (HWM) distinguish the bound-wave from free-wave components in the decomposition of an irregular wave field as well as the prediction of its resultant proper-ties. To ensure the convergence, the HWMs selectively use the conventional and phase modulation approaches to address the nonlinear interactions between-free-wave components of different frequency ratios. The models are able to predict resultant wave properties accurately and deterministically based on the time-series measurements at fixed points. Four examples of their applications to the prediction of wave properties and wave-structure interactions are presented, which demonstrate the usefulness of HWMs to the studies of ocean surface waves.

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14

Montalvo, P., R. Kraenkel, M. A. Manna e C. Kharif. "Wind-wave amplification mechanisms: possible models for steep wave events in finite depth". Natural Hazards and Earth System Sciences Discussions 1, n. 4 (8 luglio 2013): 3099–127. http://dx.doi.org/10.5194/nhessd-1-3099-2013.

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Abstract. We extend the Miles' mechanism of wind-wave generation to finite depth. A β-Miles linear growth rate depending on the depth and wind velocity is derived and allows the study of linear growth rates of surface waves from weak to moderate winds in finite depth h. The evolution of β is plotted, for several values of the dispersion parameter kh with k the wave number. For constant depths we find that no matter what the values of wind velocities are, at small enough wave age the β-Miles linear growth rates are in the known deep water limit. However winds of moderate intensities prevent the waves from growing beyond a critical wave age, which is also constrained by the water depth and is less than the wave age limit of deep water. Depending on wave age and wind velocity, the Jeffreys' and Miles' mechanisms are compared to determine which of them dominates. A wind-forced nonlinear Schrödinger equation is derived and the Akhmediev, Peregrine and Kuznetsov–Ma breather solutions for weak wind inputs in finite depth h are obtained.

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Montalvo, P., R. Kraenkel, M. A. Manna e C. Kharif. "Wind-wave amplification mechanisms: possible models for steep wave events in finite depth". Natural Hazards and Earth System Sciences 13, n. 11 (8 novembre 2013): 2805–13. http://dx.doi.org/10.5194/nhess-13-2805-2013.

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Abstract. We extend the Miles mechanism of wind-wave generation to finite depth. A β-Miles linear growth rate depending on the depth and wind velocity is derived and allows the study of linear growth rates of surface waves from weak to moderate winds in finite depth h. The evolution of β is plotted, for several values of the dispersion parameter kh with k the wave number. For constant depths we find that no matter what the values of wind velocities are, at small enough wave age the β-Miles linear growth rates are in the known deep-water limit. However winds of moderate intensities prevent the waves from growing beyond a critical wave age, which is also constrained by the water depth and is less than the wave age limit of deep water. Depending on wave age and wind velocity, the Jeffreys and Miles mechanisms are compared to determine which of them dominates. A wind-forced nonlinear Schrödinger equation is derived and the Akhmediev, Peregrine and Kuznetsov–Ma breather solutions for weak wind inputs in finite depth h are obtained.

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She Liam, Lie, D. Adytia e E. van Groesen. "Embedded wave generation for dispersive surface wave models". Ocean Engineering 80 (aprile 2014): 73–83. http://dx.doi.org/10.1016/j.oceaneng.2014.01.008.

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Franjic, F., e S. Sorella. "Spin-Wave Wave Function for Quantum Spin Models". Progress of Theoretical Physics 97, n. 3 (1 marzo 1997): 399–406. http://dx.doi.org/10.1143/ptp.97.399.

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Zhu, Zhenya, e M. Nafi Toksöz. "Seismoelectric and seismomagnetic measurements in fractured borehole models". GEOPHYSICS 70, n. 4 (luglio 2005): F45—F51. http://dx.doi.org/10.1190/1.1996907.

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Seismoelectric and seismomagnetic fields generated by seismic waves in fluid-saturated fractured borehole models are experimentally investigated with an electrode and a Hall-effect sensor. In a borehole with a horizontal fracture, the Stoneley and flexural waves induce seismoelectric and seismomagnetic fields on the borehole wall and an electromagnetic wave propagating at light speed at the horizontal fracture. In a borehole with a vertical fracture, the acoustic field generated by a monopole or dipole source is similar to that in a borehole without a vertical fracture. However, the acoustic wave propagating along the vertical fracture induces seismoelectric and seismomagnetic fields, whose apparent velocities are equal to that of a Stoneley wave. Experimental results show that two different kinds of electric and magnetic fields are generated by acoustic waves in borehole models with horizontal and/or vertical fractures. One is an electromagnetic wave propagating with light speed. The second is a stationary or localized seismoelectric and seismomagnetic field. Seismoelectric and seismomagnetic measurements might be a new logging technique for exploring fractures in a borehole.

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Chen, Shuyi S., Wei Zhao, Mark A. Donelan e Hendrik L. Tolman. "Directional Wind–Wave Coupling in Fully Coupled Atmosphere–Wave–Ocean Models: Results from CBLAST-Hurricane". Journal of the Atmospheric Sciences 70, n. 10 (1 ottobre 2013): 3198–215. http://dx.doi.org/10.1175/jas-d-12-0157.1.

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Abstract The extreme high winds, intense rainfall, large ocean waves, and copious sea spray in hurricanes push the surface-exchange parameters for temperature, water vapor, and momentum into untested regimes. The Coupled Boundary Layer Air–Sea Transfer (CBLAST)-Hurricane program is aimed at developing improved coupling parameterizations (using the observations collected during the CBLAST-Hurricane field program) for the next-generation hurricane research prediction models. Hurricane-induced surface waves that determine the surface stress are highly asymmetric, which can affect storm structure and intensity significantly. Much of the stress is supported by waves in the wavelength range of 0.1–10 m, which is the unresolved “spectral tail” in present wave models. A directional wind–wave coupling method is developed to include effects of directionality of the wind and waves in hurricanes. The surface stress vector is calculated using the two-dimensional wave spectra from a wave model with an added short-wave spectral tail. The wind and waves are coupled in a vector form rather than through the traditional roughness scalar. This new wind–wave coupling parameterization has been implemented in a fully coupled atmosphere–wave–ocean model with 1.67-km grid resolution in the atmospheric model, which can resolve finescale features in the extreme high-wind region of the hurricane eyewall. It has been tested in a number of storms including Hurricane Frances (2004), which is one of the best-observed storms during the CBLAST-Hurricane 2004 field program. This paper describes the new wind–wave coupling parameterization and examines the characteristics of the coupled model simulations of Hurricane Frances (2004). Observations of surface waves and winds are used to evaluate the coupled model results.

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Løvholt, F., S. Glimsdal, P. Lynett e G. Pedersen. "Simulating tsunami propagation in fjords with long wave models". Natural Hazards and Earth System Sciences Discussions 2, n. 8 (1 agosto 2014): 4857–87. http://dx.doi.org/10.5194/nhessd-2-4857-2014.

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Abstract. Tsunamis induced by rock slides constitute a severe hazard towards coastal fjord communities. Fjords are narrow and rugged with steep slopes, and modeling the short-frequency and high-amplitude tsunamis in this environment is demanding. In the present paper, our ability (and the lack thereof) to simulate tsunami propagation and run-up in fjords for typical wave characteristics of rock slide induced waves is demonstrated. The starting point is a 1 : 500 scale model of the topography and bathymetry of Storfjorden fjord system in western Norway. Using measured wave data from the scale model as input to numerical simulations, we find that the leading wave is moderately influenced by non-linearity and dispersion. For the trailing waves, dispersion and dissipation from the alongshore inundation on the traveling wave become more important. Tsunami inundation were simulated at the two locations of Hellesylt and Geiranger, providing good match with the measurements in the former location. In Geiranger, the most demanding case of the two, discrepancies are larger, which may in part be explained by scale effects, and in part combinations of errors emerging from both wave propagation along large stretches of the fjord and the inundation model itself.

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Li, Qinjun, Danyal Soybaş, Onur Alp Ilhan, Gurpreet Singh e Jalil Manafian. "Pure Traveling Wave Solutions for Three Nonlinear Fractional Models". Advances in Mathematical Physics 2021 (9 aprile 2021): 1–18. http://dx.doi.org/10.1155/2021/6680874.

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Three nonlinear fractional models, videlicet, the space-time fractional 1 + 1 Boussinesq equation, 2 + 1 -dimensional breaking soliton equations, and SRLW equation, are the important mathematical approaches to elucidate the gravitational water wave mechanics, the fractional quantum mechanics, the theoretical Huygens’ principle, the movement of turbulent flows, the ion osculate waves in plasma physics, the wave of leading fluid flow, etc. This paper is devoted to studying the dynamics of the traveling wave with fractional conformable nonlinear evaluation equations (NLEEs) arising in nonlinear wave mechanics. By utilizing the oncoming exp − Θ q -expansion technique, a series of novel exact solutions in terms of rational, periodic, and hyperbolic functions for the fractional cases are derived. These types of long-wave propagation phenomena played a dynamic role to interpret the water waves as well as mathematical physics. Here, the form of the accomplished solutions containing the hyperbolic, rational, and trigonometric functions is obtained. It is demonstrated that our proposed method is further efficient, general, succinct, powerful, and straightforward and can be asserted to install the new exact solutions of different kinds of fractional equations in engineering and nonlinear dynamics.

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Gagarina, E., J. van der Vegt e O. Bokhove. "Horizontal circulation and jumps in Hamiltonian wave models". Nonlinear Processes in Geophysics 20, n. 4 (12 luglio 2013): 483–500. http://dx.doi.org/10.5194/npg-20-483-2013.

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Abstract. We are interested in the modelling of wave-current interactions around surf zones at beaches. Any model that aims to predict the onset of wave breaking at the breaker line needs to capture both the nonlinearity of the wave and its dispersion. We have therefore formulated the Hamiltonian dynamics of a new water wave model, incorporating both the shallow water and pure potential flow water wave models as limiting systems. It is based on a Hamiltonian reformulation of the variational principle derived by Cotter and Bokhove (2010) by using more convenient variables. Our new model has a three-dimensional velocity field consisting of the full three-dimensional potential velocity field plus extra horizontal velocity components. This implies that only the vertical vorticity component is nonzero. Variational Boussinesq models and Green–Naghdi equations, and extensions thereof, follow directly from the new Hamiltonian formulation after using simplifications of the vertical flow profile. Since the full water wave dispersion is retained in the new model, waves can break. We therefore explore a variational approach to derive jump conditions for the new model and its Boussinesq simplifications.

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Chen, Xuanyu, Isaac Ginis e Tetsu Hara. "Sensitivity of Offshore Tropical Cyclone Wave Simulations to Spatial Resolution in Wave Models". Journal of Marine Science and Engineering 6, n. 4 (11 ottobre 2018): 116. http://dx.doi.org/10.3390/jmse6040116.

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This study investigated and quantified the sensitivity of tropical cyclone (TC) wave simulations in the open ocean to different spatial resolutions ( 1 / 3 ∘ , 1 / 6 ∘ , 1 / 12 ∘ and 1 / 24 ∘ ) using two wave models, WAVEWATCH III (WW3) and Simulating WAves Nearshore (SWAN). Six idealized TCs of different radii of maximum winds (25 km and 50 km), and of different translation speeds (3 m/s, 6 m/s and 9 m/s) were prescribed to force these two wave models. Results from both models show that the coarsest resolution ( 1 / 3 ∘ ) introduces significant errors in both the significant wave height (SWH) and the mean wavelength. Moreover, results reveal that sensitivity to spatial resolution strongly depends on storm characteristics. Waves simulated under the small (25 km) and fast moving (9 m/s) TC show the largest sensitivity to the coarse spatial resolutions. With the 1 / 3 ∘ resolution, maximum SWH can be underestimated by as much as 6% in WW3 and 16% in SWAN compared to those with the 1 / 24 ∘ resolution. These findings from the idealized TC simulations are further confirmed by wave simulations under a historical storm. Our analysis also demonstrates that spatial smoothing of the input wind field with coarse grids is not the only reason for the errors in wave simulations.

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Løvholt, F., S. Glimsdal, P. Lynett e G. Pedersen. "Simulating tsunami propagation in fjords with long-wave models". Natural Hazards and Earth System Sciences 15, n. 3 (27 marzo 2015): 657–69. http://dx.doi.org/10.5194/nhess-15-657-2015.

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Abstract. Tsunamis induced by rock slides constitute a severe hazard towards coastal fjord communities. Fjords are narrow and rugged with steep slopes, and modeling the short-frequency and high-amplitude tsunamis in this environment is demanding. In the present paper, our ability (and the lack thereof) to simulate tsunami propagation and run-up in fjords for typical wave characteristics of rock-slide-induced waves is demonstrated. The starting point is a 1 : 500 scale model of the topography and bathymetry of the southern part of Storfjorden fjord system in western Norway. Using measured wave data from the scale model as input to numerical simulations, we find that the leading wave is moderately influenced by nonlinearity and dispersion. For the trailing waves, dispersion and dissipation from the alongshore inundation on the traveling wave become more important. The tsunami inundation was simulated at the two locations of Hellesylt and Geiranger, providing a good match with the measurements in the former location. In Geiranger, the most demanding case of the two, discrepancies are larger. The discrepancies may be explained by a combinations of factors, such as the accumulated errors in the wave propagation along large stretches of the fjord, the coarse grid resolution needed to ensure model stability, and scale effects in the laboratory experiments.

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Booij, Nico, e Leo H. Holthuijsen. "Propagation of ocean waves in discrete spectral wave models". Journal of Computational Physics 68, n. 2 (febbraio 1987): 307–26. http://dx.doi.org/10.1016/0021-9991(87)90060-x.

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HLAVATÝ, LADISLAV, e IVO PETR. "NEW SOLVABLE SIGMA MODELS IN PLANE-PARALLEL WAVE BACKGROUND". International Journal of Modern Physics A 29, n. 02 (20 gennaio 2014): 1450009. http://dx.doi.org/10.1142/s0217751x14500092.

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We explicitly solve the classical equations of motion for strings in backgrounds obtained as non-Abelian T-duals of a homogeneous isotropic plane-parallel wave. To construct the dual backgrounds, semi-Abelian Drinfeld doubles are used which contain the isometry group of the homogeneous plane wave metric. The dual solutions are then found by the Poisson–Lie transformation of the explicit solution of the original homogeneous plane wave background. Investigating their Killing vectors, we have found that the dual backgrounds can be transformed to the form of more general plane-parallel waves.

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Valentina Socco, Laura, e Cesare Comina. "Time-average velocity estimation through surface-wave analysis: Part 2 — P-wave velocity". GEOPHYSICS 82, n. 3 (1 maggio 2017): U61—U73. http://dx.doi.org/10.1190/geo2016-0368.1.

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Surface waves (SWs) in seismic records can be used to extract local dispersion curves (DCs) along a seismic line. These curves can be used to estimate near-surface S-wave velocity models. If the velocity models are used to compute S-wave static corrections, the required information consists of S-wave time-average velocities that define the one-way time for a given datum plan depth. However, given the wider use of P-wave reflection seismic with respect to S-wave surveys, the estimate of P-wave time-average velocity would be more useful. We therefore focus on the possibility of also extracting time-average P-wave velocity models from SW dispersion data. We start from a known 1D S-wave velocity model along the line, with its relevant DC, and we estimate a wavelength/depth relationship for SWs. We found that this relationship is sensitive to Poisson’s ratio, and we develop a simple method for estimating an “apparent” Poisson’s ratio profile, defined as the Poisson’s ratio value that relates the time-average S-wave velocity to the time-average P-wave velocity. Hence, we transform the time-average S-wave velocity models estimated from the DCs into the time-average P-wave velocity models along the seismic line. We tested the method on synthetic and field data and found that it is possible to retrieve time-average P-wave velocity models with uncertainties mostly less than 10% in laterally varying sites and one-way traveltime for P-waves with less than 5 ms uncertainty with respect to P-wave tomography data. To our knowledge, this is the first method for reliable estimation of P-wave velocity from SW data without any a priori information or additional data.

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28

Zhu, Zhenya, Matthijs W. Haartsen e M. Nafi Toksöz. "Experimental studies of electrokinetic conversions in fluid‐saturated borehole models". GEOPHYSICS 64, n. 5 (settembre 1999): 1349–56. http://dx.doi.org/10.1190/1.1444639.

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Experimental and theoretical studies show that there are electromagnetic (EM) fields generated by seismic waves with two kinds of conversion mechanisms in a fluid‐saturated, porous medium. Within a homogeneous formation, the seismic wave generates a seismoelectric field that exists only in the area disturbed by the seismic wave and whose apparent velocity is that of the seismic wave. At an interface between differing formation properties, the generated seismoelectric wave is a propagating EM wave that can be detected everywhere. An electrode, used as a receiver on the ground surface, can detect the propagating EM wave generated at an interface, but cannot detect the seismoelectric field generated in a homogeneous formation. When the electrode is in a borehole and close to a porous formation, it can detect both the EM waves and the seismoelectric field. In this paper, electrokinetic measurements are performed with borehole models made of natural rocks or artificial materials. Experimental results show that the Stoneley wave and other acoustic modes, excited by a monopole source in the borehole models, generate seismoelectric fields in fluid‐saturated formations. The electric components of the seismoelectric fields can be detected by an electrode in the borehole or on the borehole wall. The amplitude and frequency of the seismoelectric fields are related not only to the seismic wave, but also to formation properties such as permeability, conductivity, etc. Comparison between the waveforms of the seismoelectric signals and acoustic logging waves suggests that seismoelectric well logging may explore the different properties of the formation. Electroseismic measurements are also performed with these borehole models. The electric pulse through the electrode in the borehole or on the borehole wall induces Stoneley waves in fluid‐saturated models that can be received by a monopole transducer in the same borehole. These measurement methods (seismoelectric logging or electroseismic logging) might directly apply to well logging to investigate formation properties related to the pore fluid flow.

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29

FLEMING, C. A. "TECHNICAL NOTE. HYDRODYNAMIC WAVE MODELS." Proceedings of the Institution of Civil Engineers - Water Maritime and Energy 96, n. 3 (settembre 1992): 193–96. http://dx.doi.org/10.1680/iwtme.1992.21089.

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30

Wurbs, Ralph A. "Dam‐Breach Flood Wave Models". Journal of Hydraulic Engineering 113, n. 1 (gennaio 1987): 29–46. http://dx.doi.org/10.1061/(asce)0733-9429(1987)113:1(29).

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31

Lindgren, G. "Wave analysis by Slepian models". Probabilistic Engineering Mechanics 15, n. 1 (gennaio 2000): 49–57. http://dx.doi.org/10.1016/s0266-8920(99)00008-9.

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32

Degasperis, Antonio. "Integrable nonlocal wave interaction models". Journal of Physics A: Mathematical and Theoretical 44, n. 5 (10 gennaio 2011): 052002. http://dx.doi.org/10.1088/1751-8113/44/5/052002.

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33

Amini, Erfan, Danial Golbaz, Fereidoun Amini, Meysam Majidi Nezhad, Mehdi Neshat e Davide Astiaso Garcia. "A Parametric Study of Wave Energy Converter Layouts in Real Wave Models". Energies 13, n. 22 (20 novembre 2020): 6095. http://dx.doi.org/10.3390/en13226095.

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Ocean wave energy is a broadly accessible renewable energy source; however, it is not fully developed. Further studies on wave energy converter (WEC) technologies are required in order to achieve more commercial developments. In this study, four CETO6 spherical WEC arrangements have been investigated, in which a fully submerged spherical converter is modelled. The numerical model is applied using linear potential theory, frequency-domain analysis, and irregular wave scenario. We investigate a parametric study of the distance influence between WECs and the effect of rotation regarding significant wave direction in each arrangement compared to the pre-defined layout. Moreover, we perform a numerical landscape analysis using a grid search technique to validate the best-found power output of the layout in real wave models of four locations on the southern Australian coast. The results specify the prominent role of the distance between WECs, along with the relative angle of the layout to dominant wave direction, in harnessing more power from the waves. Furthermore, it is observed that a rise in the number of WECs contributed to an increase in the optimum distance between converters. Consequently, the maximum exploited power from each buoy array has been found, indicating the optimum values of the distance between buoys in different real wave scenarios and the relative angle of the designed layout with respect to the dominant in-site wave direction.

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34

Badulin, S. I., V. G. Grigorieva, L. Aouf e A. Dalphinet. "HIGH RESOLUTION WAVE FORECASTING MODELS AND WAVE TURBULENCE THEORY". XXII workshop of the Council of nonlinear dynamics of the Russian Academy of Sciences 47, n. 1 (30 aprile 2019): 15–17. http://dx.doi.org/10.29006/1564-2291.jor-2019.47(1).3.

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Results of high resolution sea wave modeling are treated within the theory of wave (weak) turbulence. Spatial resolution 1 km is shown likely to be excessive and lead to appearance of artificial structures in fields of wave periods and steepness. The research was supported by the state assignment of IO RAS, theme 0149-2019-0002.

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35

Boiero, Daniele. "Surface wave analysis for building shear wave velocity models". GEOPHYSICS 76, n. 2 (marzo 2011): Z27. http://dx.doi.org/10.1190/1.3574120.

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36

Grimshaw, Roger, Dmitry Pelinovsky, Efim Pelinovsky e Tatiana Talipova. "Wave group dynamics in weakly nonlinear long-wave models". Physica D: Nonlinear Phenomena 159, n. 1-2 (novembre 2001): 35–57. http://dx.doi.org/10.1016/s0167-2789(01)00333-5.

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37

Sun, Weitao, Jing Ba, Tobias M. Müller, José M. Carcione e Hong Cao. "Comparison ofP-wave attenuation models of wave-induced flow". Geophysical Prospecting 63, n. 2 (14 novembre 2014): 378–90. http://dx.doi.org/10.1111/1365-2478.12196.

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38

Krasheninnikov, V. R., e A. U. Subbotin. "Double stochastic wave models of multidimensional random fields". Information Technology and Nanotechnology, n. 2391 (2019): 41–47. http://dx.doi.org/10.18287/1613-0073-2019-2391-41-47.

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The paper deals with the development of mathematical models of random fields to describe and simulate images. In the wave model, a random field is the result of the influence of perturbations (waves) that occur at random times in random places and have random shapes. This model allows representing and simulate isotropic and anisotropic images (and their temporal sequences) defined on arbitrary areas of multidimensional space, as well as on any surfaces. The problems of correlation analysis and synthesis can be relatively easily solved. However, this model allows representing only homogeneous fields. In this paper, we consider «double stochastic» wave models, when the first wave random field (control field) sets the parameters of the second (controlled field). As a result, the controlled field becomes nonuniform, since its parameters vary randomly. We also consider options when two fields mutually influence each other. These models allow us to represent and simulate multidimensional inhomogeneous images (and their temporal sequences), as well as systems of such images with mutual correlations.

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39

Kachulin, Dmitry, Alexander Dyachenko e Vladimir Zakharov. "Soliton Turbulence in Approximate and Exact Models for Deep Water Waves". Fluids 5, n. 2 (10 maggio 2020): 67. http://dx.doi.org/10.3390/fluids5020067.

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We investigate and compare soliton turbulence appearing as a result of modulational instability of the homogeneous wave train in three nonlinear models for surface gravity waves: the nonlinear Schrödinger equation, the super compact Zakharov equation, and the fully nonlinear equations written in conformal variables. We show that even at a low level of energy and average wave steepness, the wave dynamics in the nonlinear Schrödinger equation fundamentally differ from the dynamics in more accurate models. We study energy losses of wind waves due to their breaking for large values of total energy in the super compact Zakharov equation and in the exact equations and show that in both models, the wave system loses 50% of energy very slowly, during few days.

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40

Dupuis, L., e Y. Ouellet. "Prévision des vagues dans l'estuaire du Saint-Laurent à l'aide d'un modèle bidimensionnel". Canadian Journal of Civil Engineering 26, n. 6 (1 dicembre 1999): 713–23. http://dx.doi.org/10.1139/l99-033.

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Until now, wave hindcasting in the Estuary and Gulf of St. Lawrence has been done with one-dimensional models. The objective of the present paper is to verify if the two-dimensional model WAWSP, developed to predict waves on the Great Lakes, could be used in the St. Lawrence estuary, a semi-open fetch limited region. Waves (significant wave heights, peak periods, and directions) hindcast by this 2D model are compared with wave data observed at two buoys in 1991, 1992, and 1993, as well as with the ones obtained with 1D models SPM-77 and SPM-84. As a whole, the 2D model gives better results than 1D models. Wave heights are well reproduced, as long as wind data are well represented. However, wave periods are much smaller than those measured, and wave directions are not accurate, mainly because of the presence of swell in the estuary. This study shows the need to obtain more wave data with better quality in order to validate wave hindcasting models.Key words: water waves, numerical modeling, wave hindcasting, 2D model, wave climate, wave height, wave period, wave direction, calculated versus measured waves.

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41

Vogel, J. A., A. C. Radder e J. H. De Reus. "VERIFICATION OF NUMERICAL WAVE PROPAGATION MODELS IN TIDAL INLETS". Coastal Engineering Proceedings 1, n. 21 (29 gennaio 1988): 30. http://dx.doi.org/10.9753/icce.v21.30.

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The performance of two numerical wave propagation models has been investigated by comparison with field data. The first model is a refractiondiffraction model based on the parabolic equation method. The second is a refraction model based on the wave action equation, using a regular grid. Two field situations, viz. a tidal inlet and a river estuary along the Dutch coast, were used to determine the influence of the local wind on waves behind an island and a breaker zone. It may be concluded from the results of the computations and measurements that a much better agreement is obtained when wave growth due to wind is properly accounted for in the numerical models. In complicated coastal areas the models perform well for both engineering and research purposes.

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42

Pravica, D. W., N. Randriampiry e M. J. Spurr. "-Advanced Models for Tsunami and Rogue Waves". Abstract and Applied Analysis 2012 (2012): 1–26. http://dx.doi.org/10.1155/2012/414060.

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A wavelet , that satisfies theq-advanced differential equation for , is used to modelN-wave oscillations observed in tsunamis. Althoughq-advanced ODEs may seem nonphysical, we present an application that model tsunamis, in particular the Japanese tsunami of March 11, 2011, by utilizing a one-dimensional wave equation that is forced by . The profile is similar to tsunami models in present use. The function is a wavelet that satisfies aq-advanced harmonic oscillator equation. It is also shown that another wavelet, , matches a rogue-wave profile. This is explained in terms of a resonance wherein two small amplitude forcing waves eventually lead to a large amplitude rogue. Since wavelets are used in the detection of tsunamis and rogues, the signal-analysis performance of and is examined on actual data.

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43

Stephan, Claudia, M. Joan Alexander e Jadwiga H. Richter. "Characteristics of Gravity Waves from Convection and Implications for Their Parameterization in Global Circulation Models". Journal of the Atmospheric Sciences 73, n. 7 (24 giugno 2016): 2729–42. http://dx.doi.org/10.1175/jas-d-15-0303.1.

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Abstract Characteristic properties of gravity waves from convection over the continental United States are derived from idealized high-resolution numerical simulations. In a unique modeling approach, waves are forced by a realistic thermodynamic source based on observed precipitation data. The square of the precipitation rate and the gravity wave momentum fluxes both show lognormal occurrence distributions, with long tails of extreme events. Convectively generated waves can give forces in the lower stratosphere that at times rival orographic wave forcing. Throughout the stratosphere, zonal forces due to convective wave drag are much stronger than accounted for by current gravity wave drag parameterizations, so their contribution to the summer branch of the stratospheric Brewer–Dobson circulation is in fact much larger than models predict. A comparison of these forces to previous estimates of the total drag implies that convectively generated gravity waves are a primary source of summer-hemisphere stratospheric wave drag. Furthermore, intermittency and strength of the zonal forces due to convective gravity wave drag in the lower stratosphere resemble analysis increments, suggesting that a more realistic representation of these waves may help alleviate model biases on synoptic scales. The properties of radar precipitation and gravity waves seen in this study lead to a proposed change for future parameterization methods that would give more realistic drag forces in the stratosphere without compromising mesospheric gravity wave drag.

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44

Teng, Yunfei, Lin Lu, Liang Cheng, Feifei Tong e Guoqiang Tang. "DEFECT FUNCTION MODELS FOR THE WAVE BOUNDARY LAYERS". Coastal Engineering Proceedings, n. 36v (28 dicembre 2020): 2. http://dx.doi.org/10.9753/icce.v36v.waves.2.

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The boundary layer flow induced by surface waves has been extensively investigated due to its significance in engineering applications such as sediment transport and hydrodynamic forces on subsea structures. Several forms of defect functions (referred to as DF hereafter) were developed in the past decades, e.g. Sleath (1970, 1982), Nielsen (1985, 2016) and etc., due to their good efficiency in the description of the velocity distribution in one dimensional wave boundary layer (WBL). In this work, two forms of DFs are proposed: (i) DF-I describes the velocity distributions and bottom shear stresses in phase space with 4 model parameters; (ii) DF-II describes the maximum WBL profile with 3 model parameters. A number of datasets to support the validation of the DFs were obtained through experimental and numerical tests. Two sets of experiments were conducted individually in a free-surface-wave flume located in Dalian University of Technology and an oscillating-flow flume located in the University of Western Australia. For the free surface wave tests, the velocity was measured.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/RK-z0Q8rTjk

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45

Firdaus, Nurman, Baharuddin Ali, Mochammad Nasir e M. Muryadin. "The Wave Heights Distribution of Random Wave Based on Ocean Basin". Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan 17, n. 3 (1 ottobre 2020): 114–22. http://dx.doi.org/10.14710/kapal.v17i3.31021.

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The wave height parameter in ocean waves is one of the important information for a marine structure design. The present paper investigates the results of wave heights distribution from laboratory-generated for single sea state. Data of the random wave time series collected at the ocean basin are analyzed using the wave spectrum and compared with the theoretical spectrum in this study. The random wave data is varied with four sea states consisting of sea states 3, 4, 5 and 6 obtained from laboratory measurements. The parameter conditions of generated sea waves are represented by a value of significant wave height and wave peak period in the range of sea states. The individual wave heights data in each sea state are presented in the form of exceedance probability distribution and the predictions using a linear model. This study aims to estimate the wave heights distribution using the Rayleigh and Weibull distribution model. Furthermore, the accuracy of the wave heights distribution data's prediction results in each sea state has been compared and examined for both models. The applied linear models indicate similar and reasonable estimations on the observed data trends.

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46

Hong, Woo-Pyo. "Dynamics of Combined Solitary-waves in the General Shallow Water Wave Models". Zeitschrift für Naturforschung A 58, n. 9-10 (1 ottobre 2003): 520–28. http://dx.doi.org/10.1515/zna-2003-9-1008.

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We find new analytic solitary-wave solutions, having a nonzero background at infinity, of the general fifth-order shallow water wave models using the hyperbolic function ansatz method. We study the dynamical properties of the solutions in the combined form of a bright and a dark solitary-wave by using numerical simulations. It is shown that the solitary-waves can be stable or marginally stable, depending on the coefficients of the model.We study the interaction dynamics by using the combined solitary-waves as the initial profiles to show the formation of sech2-type solitary-waves in the presence of a strong nonlinear dispersion term. - PACS: 03.40.Kf, 02.30.Jr, 47.20.Ky, 52.35.Mw

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47

Sundaravadivelu, R., R. Harps e O. Mahrenholtz. "Twin Floating Connected Models in Regular Beam Waves". Journal of Offshore Mechanics and Arctic Engineering 114, n. 4 (1 novembre 1992): 242–49. http://dx.doi.org/10.1115/1.2919976.

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This paper presents the studies carried out on twin floating models connected alongside with hinge connection in regular beam waves of different frequencies in a wave flume. The heave, roll and sway, normalized with the wave amplitude are reported for a single box, a single half-cylinder, twin boxes and twin half-cylinders. The effect of separation distance and stiffness of the connection on the response of the twin models are also reported.

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48

Athanasopoulos, Nikolaos, Edgar Manukyan, Thomas Bohlen e Hansruedi Maurer. "Time–frequency windowing in multiparameter elastic FWI of shallow seismic wavefield". Geophysical Journal International 222, n. 2 (15 maggio 2020): 1164–77. http://dx.doi.org/10.1093/gji/ggaa242.

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SUMMARY Full-waveform inversion of shallow seismic wavefields is a promising method to infer multiparameter models of elastic material properties (S-wave velocity, P-wave velocity and mass density) of the shallow subsurface with high resolution. Previous studies used either the refracted Pwaves to reconstructed models of P-wave velocity or the high-amplitude Rayleigh waves to infer the S-wave velocity structure. In this work, we propose a combination of both wavefields using continuous time–frequency windowing. We start with the contribution of refracted P waves and gradually increase the time window to account for scattered body waves, higher mode Rayleigh waves and finally the fundamental Rayleigh wave mode. The opening of the time window is combined with opening the frequency bandwidth of input signals to avoid cycle skipping. Synthetic reconstruction tests revealed that the reconstruction of P-wave velocity model and mass density can be improved. The S-wave velocity reconstruction is still accurate and robust and is slightly benefitted by time–frequency windowing. In a field data application, we observed that time–frequency windowing improves the consistency of multiparameter models. The inferred models are in good agreement with independent geophysical information obtained from ground-penetrating radar and full-waveform inversion of SH waves.

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49

Watanabe, S., K. Sato, Y. Kawatani e M. Takahashi. "Vertical resolution dependence of gravity wave momentum flux simulated by an atmospheric general circulation model". Geoscientific Model Development 8, n. 6 (2 giugno 2015): 1637–44. http://dx.doi.org/10.5194/gmd-8-1637-2015.

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Abstract. The dependence of the gravity wave spectra of energy and momentum flux on the horizontal resolution and time step of atmospheric general circulation models (AGCMs) has been thoroughly investigated in the past. In contrast, much less attention has been given to the dependence of these gravity wave parameters on models' vertical resolutions. The present study demonstrates the dependence of gravity wave momentum flux (GWMF) in the stratosphere and mesosphere on the model's vertical resolution, which is evaluated using an AGCM with a horizontal resolution of about 0.56°. We performed a series of sensitivity test simulations changing only the model's vertical resolution above a height of 8 km, and found a global reduction of GWMF with increasing vertical resolution. Inertial gravity waves with short vertical wavelengths simulated at higher vertical resolutions might play an important role in determining GWMF in the summertime stratosphere. The sensitivity test simulation also demonstrated the importance of the model's vertical resolution on representing realistic behaviors of gravity waves near their critical level.

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50

Boateng, Kwasi, Weigou Yang, Michael Ezra Otoo e David Yaro. "Dispersive Traveling Wave Solution for Non-Linear Waves Dynamical Models". Journal of Applied Mathematics and Physics 07, n. 10 (2019): 2467–80. http://dx.doi.org/10.4236/jamp.2019.710167.

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