Small water channel network for designing wave fields in shallow water

2018 ◽  
Vol 849 ◽  
pp. 90-110 ◽  
Author(s):  
Takahito Iida ◽  
Masashi Kashiwagi
Keyword(s):  
Transmission Line ◽  
Shallow Water ◽  
Water Waves ◽  
Design Method ◽  
Water Channel ◽  
Electric Circuit ◽  
Linear Potential ◽  
Channel Network ◽  
Wave Fields ◽  
Small Water

A small water channel network is proposed for designing shallow water fields, and the network is applied to attain water wave cloaking. The design formula is derived from an analogy between waves in a water channel and in an electric circuit; an approach of a transmission line metamaterial is extended to water waves and the water channel is used as an alternative of the transmission line. The size of the water channel is sufficiently smaller than the wavelength and a number of the channels are periodically connected as a network. This small water channel network makes artificial wave fields, and it works for a wide band of frequencies. First, we make an isotropic network equivalent to a shallow water space with constant depth in order to validate the proposed design method. It shows no wave reflection at the interface due to impedance matching. After that, the proposed theory is applied to designing an anisotropic small water channel network for demonstrating shallow water cloaking. A cylinder is cloaked from waves by the network surrounding the cylinder. Both cases are confirmed with numerical computations by solving the boundary-value problem based on linear potential theory.

scholarly journals On the feasibility of the use of wind SAR to downscale waves on shallow water

Ocean Science ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 39-49 ◽  
Author(s):  
O. Q. Gutiérrez ◽  
F. Filipponi ◽  
A. Taramelli ◽  
E. Valentini ◽  
P. Camus ◽  
...  
Keyword(s):  
Shallow Water ◽  
Spatial Resolution ◽  
Water Waves ◽  
Wave Climate ◽  
Wind Fields ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Wave Fields ◽  
Wind Regimes ◽  
Offshore Wave

Abstract. In recent years, wave reanalyses have become popular as a powerful source of information for wave climate research and engineering applications. These wave reanalyses provide continuous time series of offshore wave parameters; nevertheless, in coastal areas or shallow water, waves are poorly described because spatial resolution is not detailed. By means of wave downscaling, it is possible to increase spatial resolution in high temporal coverage simulations, using forcing from wind and offshore wave databases. Meanwhile, the reanalysis wave databases are enough to describe the wave climate at the limit of simulations; wind reanalyses at an adequate spatial resolution to describe the wind structure near the coast are not frequently available. Remote sensing synthetic aperture radar (SAR) has the ability to detect sea surface signatures and estimate wind fields at high resolution (up to 300 m) and high frequency. In this work a wave downscaling is done on the northern Adriatic Sea, using a hybrid methodology and global wave and wind reanalysis as forcing. The wave fields produced were compared to wave fields produced with SAR winds that represent the two dominant wind regimes in the area: the bora (ENE direction) and sirocco (SE direction). Results show a good correlation between the waves forced with reanalysis wind and SAR wind. In addition, a validation of reanalysis is shown. This research demonstrates how Earth observation products, such as SAR wind fields, can be successfully up-taken into oceanographic modeling, producing similar downscaled wave fields when compared to waves forced with reanalysis wind.

scholarly journals Soliton spectra of random water waves in shallow basins

2018 ◽  
Vol 13 (4) ◽  
pp. 40 ◽  
Author(s):  
J.-P. Giovanangeli ◽  
C. Kharif ◽  
Y.A. Stepanyants
Keyword(s):  
Shallow Water ◽  
Wave Field ◽  
Water Waves ◽  
Wind Waves ◽  
Inverse Scattering Method ◽  
Random Wave ◽  
Scattering Method ◽  
Wave Fields ◽  
Fourier Spectra ◽  
Random Wave Field

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.

Review Lecture - Water waves and their development in space and time

1985 ◽  
Vol 400 (1818) ◽  
pp. 1-18 ◽  
Keyword(s):  
Wave Propagation ◽  
Shallow Water ◽  
Deep Water ◽  
Water Waves ◽  
Water Wave ◽  
Hydraulic Jump ◽  
Soliton Solutions ◽  
Nonlinear Effects ◽  
Wave Fields ◽  
Turbulent Bore

Most practical predictions of water-wave propagation use linear approximations based on the concepts of ‘geometric’ rays and group velocity. Although this is successful, or adequate, in many instances, there are phenomena that can only be fully understood in terms of nonlinear effects. The recent boom in soliton-related studies has shed much light on the nonlinear aspects of wave propagation in shallow water. However, for waves on deeper water some of the nonlinear effects are only now being appreciated. A few, such as the focusing pattern of steady wave fields have direct parallels in shallow water; while others, such as deep-water soliton solutions, have their own rich structure. In deep or shallow water, wavebreaking is the most eye-catching development of a wave field. With the exception of the classical turbulent bore or hydraulic jump, our present models are still some way from giving a quantitative appreciation of important effects such as energy dissipation and momentum transfer, but causes of breaking for deep-water waves are now a little better understood.

scholarly journals Mooring Drag Effects in Interaction Problems of Waves and Moored Underwater Floating Structures

2020 ◽  
Vol 8 (3) ◽  
pp. 146
Author(s):  
Cheng-Tsung Chen ◽  
Jaw-Fang Lee ◽  
Chun-Han Lo
Keyword(s):  
Water Waves ◽  
Degrees Of Freedom ◽  
Wave Force ◽  
Wave Forces ◽  
Linear Potential ◽  
Floating Structure ◽  
Mooring Lines ◽  
Wave Fields ◽  
Present Solution ◽  
Scattering And Radiation

In contrast to either considering structures with full degrees of freedom but with wave force on mooring lines neglected or with wave scattering and radiation neglected, in this paper, a new analytic solution is presented for wave interaction with moored structures of full degrees of freedom and with wave forces acting on mooring lines considered. The linear potential wave theory is applied to solve the wave problem. The wave fields are expressed as superposition of scattering and radiation waves. Wave forces acting on the mooring lines are calculated using the Morison equation with relative motions. A coupling formulation among water waves, underwater floating structure, and mooring lines are presented. The principle of energy conservation, as well as numerical results, are used to verify the present solution. With complete considerations of interactions among waves and moored structures, the characteristics of motions of the structure, the wave fields, and the wave forces acting on the mooring lines are investigated.

scholarly journals On the feasibility of the use of wind SAR to downscale waves on shallow water

2015 ◽  
Vol 12 (4) ◽  
pp. 1567-1593
Author(s):  
O. Q. Gutiérrez ◽  
F. Filipponi ◽  
A. Taramelli ◽  
E. Valentini ◽  
P. Camus ◽  
...  
Keyword(s):  
Shallow Water ◽  
Spatial Resolution ◽  
Water Waves ◽  
Wave Climate ◽  
Wind Fields ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Wave Fields ◽  
Offshore Wave ◽  
Wave Reanalysis

Abstract. On the recent years wave reanalysis have become popular as a powerful source of information for wave climate research and engineering applications. These wave reanalysis provide continuous time-series of offshore wave parameters, nevertheless on coastal areas or shallow water waves are poorly described because spatial resolution is not detailed. By means of wave downscaling it is possible to increase spatial resolution in high temporal coverage simulations, using forcing from wind and offshore wave databases. Meanwhile the reanalysis wave databases are enough to describe the wave climate on the limit of simulations, wind reanalysis at an adequate spatial resolution to describe the wind structure near the coast are not frequently available. Remote Sensing Synthetic Aperture Radar (SAR) has the ability to detect sea surface signatures and estimate wind field at high resolution (up to 300 m) and high frequency. In this work a wave downscaling is done on the northern Adriatic sea, using an hybrid methodology and Global wave and wind reanalysis as forcing. The wave fields produced were compared to wave fields produced with SAR winds that represent the two dominant wind regimes in the area: the Bora (ENE direction) and Sirocco (SE direction). Results show a good correlation between the waves forced with reanalysis wind and SAR wind. In addition, a validation of reanalysis is shown. This research demonstrates how Earth Observation products, as SAR wind fields, can be successfully up-taken into oceanographic modeling, producing similar downscaled wave field when compared to waves forced with reanalysis wind.

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