scholarly journals OBSERVATIONS OF TIE TRANSFORMATION OF OCEAN WAVE CHARACTERISTICS NEAR COASTS BY USE OF ANCHORED BUOYS

1966 ◽  
Vol 1 (10) ◽  
pp. 6
Author(s):  
Haruo Higuchi ◽  
Tadao Kakinuma
Keyword(s):  
Shallow Water ◽  
Ocean Waves ◽  
Transformation Process ◽  
Long Waves ◽  
Ocean Wave ◽  
Wave Characteristics ◽  
Wave Observation ◽  
The Waves

In order to clarify the transformation process of ocean waves in shallow water, a series of wave observations were carried out along some coasts in Japan by photographing two or three convenient buoys aligned m the direction of the waves with two 16 urn cine-cameras. The equipment and methods used in observations and analyses are here described together with some of the results obtained. By examining the motion of the buoys off the coast at Shirahama it was found that the method of wave observation by means of anchored buoys was very useful in the case of comparatively long waves.

scholarly journals DETERMINATION OF THE WAVE HEIGHT IN NATURE FROM MODEL TESTS SUPPLEMENTED BY CALCULATION

2011 ◽  
Vol 1 (6) ◽  
pp. 12
Author(s):  
J. G.H.R. Diephuis ◽  
J. G. Gerritze
Keyword(s):  
Shallow Water ◽  
Wave Height ◽  
Deep Water ◽  
Bottom Topography ◽  
Model Tests ◽  
Small Scale ◽  
Wave Characteristics ◽  
Sea Bottom ◽  
The Waves

This paper deals with the problem of determining the wave characteristics in shallow water from those in deep water. In general this can be done by means of a refraction calculation. If the sea bottom topography is too irregular the height of the waves can be determined by means of a small-scale refraction model. In both cases, however, some additional effects have to be taken into account, viz. the influence of the bottom friction and the influence of the wind.

scholarly journals CNOIDAL WAVES IN SHALLOW WATER

1964 ◽  
Vol 1 (9) ◽  
pp. 1
Author(s):  
Frank D. Masch
Keyword(s):  
Shallow Water ◽  
Power Transmission ◽  
Wave Train ◽  
Wave Theory ◽  
Finite Amplitude ◽  
Long Waves ◽  
Practical Application ◽  
Cnoidal Waves ◽  
Water Power ◽  
The Waves

The propagation of long waves of finite amplitude in water with depth to wavelength ratios less than about one-tenth and greater than about one-fiftieth can be described by cnoidal wave theory. To date little use has been made of the theory because of the difficulties involved in practical application. This paper presents the theory necessary for predicting the transforming characteristics of long waves based on cnoidal theory. Basically the method involves calculating the power transmission for a wave train m shallow water from cnoidal theory and equating this to the deep water power transmission assuming no reflections or loss of energy as the waves move into shoaling water. The equations for wave power have been programmed for the range of cnoidal waves, and the results are plotted in non-dimensional form.

scholarly journals Impact of wave physics on ocean–wave coupling in CMEMS-IBI Part B: Validation study

2019 ◽  
Author(s):  
Romain Rainaud ◽  
Lotfi Aouf ◽  
Alice Dalphinet ◽  
Marcos Garcia Sotillo ◽  
Enrique Alvarez-Fanjul ◽  
...  
Keyword(s):  
Positive Impact ◽  
Wave Model ◽  
Ocean Waves ◽  
Ocean Model ◽  
Ocean Wave ◽  
Wave Coupling ◽  
In Situ Observations ◽  
The Waves ◽  
Horizontal Grid

Abstract. This work aims to evaluate the ocean/waves coupling based on input from the wave modelMFWAM. 1-year coupled runs including seasonal variability has been performed for the IberianBiscay and Ireland domain. We investigated the consequences of improvement in wave physics onthe mixed layer of the ocean with a fine horizontal grid size of 1/36°. The ocean model NEMO andthe wave model MFWAM have been used for this study to prepare the use of coupling operationallyin the IBI Copernicus Marine Service and Monitoring Evironment (CMEMS). Two wave physicsversions have been discussed in this study. The validation of sea surface temperature, surfacecurrents have been implemented in comparison with satellite and in-situ observations. The resultsshow a positive impact of the waves forcing on surface key parameters. For storm cases it has beendemonstrated a good skill of the ocean/wave coupling to capture the peak of surge event such as theone observed for Petra storm.

scholarly journals Ship generated mini-tsunamis

2017 ◽  
Vol 816 ◽  
pp. 142-166 ◽  
Author(s):  
John Grue
Keyword(s):  
Asymptotic Analysis ◽  
Shallow Water ◽  
Wave Height ◽  
Long Waves ◽  
Qualitative Explanation ◽  
The Waves ◽  
Water Speed ◽  
Shallow Water Depth ◽  
Ship Speed ◽  
Good Agreement

Very long waves are generated when a ship moves across an appreciable depth change $\unicode[STIX]{x0394}h$ comparable to the average and relatively shallow water depth $h$ at the location, with $\unicode[STIX]{x0394}h/h\simeq 1$. The phenomenon is new and the waves were recently observed in the Oslofjord in Norway. The 0.5–1 km long waves, extending across the 2–3 km wide fjord, are observed as run-ups and run-downs along the shore, with periods of 30–60 s, where a wave height up to 1.4 m has been measured. The waves travelling with the shallow water speed, found ahead of the ships moving at subcritical depth Froude number, behave like a mini-tsunami. A qualitative explanation of the linear generation mechanism is provided by an asymptotic analysis, valid for $\unicode[STIX]{x0394}h/h\ll 1$ and long waves, expressing the generation in terms of a pressure impulse at the depth change. Complementary fully dispersive calculations for $\unicode[STIX]{x0394}h/h\simeq 1$ document symmetries of the waves at positive or negative $\unicode[STIX]{x0394}h$. The wave height grows with the ship speed $U$ according to $U^{n}$ with $n$ in the range 3–4, for $\unicode[STIX]{x0394}h/h\simeq 1$, while the growth in $U$ is only very weak for $\unicode[STIX]{x0394}h/h\ll 1$ (the asymptotics). Calculations show good agreement with observations.

Comparative spectra of microseisms and swell

1963 ◽  
Vol 53 (1) ◽  
pp. 27-37
Author(s):  
R. A. Haubrich ◽  
W. H. Munk ◽  
F. E. Snodgrass
Keyword(s):  
Shallow Water ◽  
San Diego ◽  
Ross Sea ◽  
Beam Width ◽  
Ocean Wave ◽  
Sharp Peak ◽  
Wave Spectra ◽  
Double Frequency ◽  
Frequency Peak ◽  
Primary Frequency

Abstract Spectra of seismic and ocean wave recordings near San Diego, California, show closely related features. The wave spectra consist of a sharp peak whose frequency, f(t), increases linearly with time and consistent with the expected dispersive behaviour from a source at 6150 nautical miles (presumably a storm in the Ross Sea). The seismic spectra show peaks at f(t) and at 2 f(t); the double frequency peak contains 100 times the energy of the peak at the primary frequency. A comparison between the peak frequencies and band widths of the seismic and ocean wave spectra, and an estimate of the direction and beam width of the seismic radiation, leads to the following conclusions: that the microseismic generation area is predominantly local, being confined to a distance of 100 miles up or down the coast. For the primary frequencies the generative strip is presumably confined to shallow water; for the double frequencies it extends 200 miles seaward.

The generation of waves by wind

1952 ◽  
Vol 215 (1122) ◽  
pp. 299-328 ◽  
Keyword(s):  
Ocean Waves ◽  
Irish Sea ◽  
North Coast ◽  
Empirical Relationships ◽  
The North ◽  
Component Wave ◽  
Wave Trains ◽  
The Irish Sea ◽  
The Waves ◽  
Group Velocities

This paper describes an investigation of the height and length of ocean waves and swell in relation to the strength, extent and duration of the wind in the generating area, and the subsequent travel of the swell through calm and disturbed water. The investigation is based on records of waves made on the north coast of Cornwall, in the Irish Sea and in Lough Neagh. It is a practical continuation of the work of Barber & Ursell (1948), who showed that the waves leaving the generating area behave as a continuous spectrum of component wave trains which travel independently with the group velocities appropriate to their periods. The spectral distribution of energy in the storm area is considered, and the relative amplitudes of the different components are deduced empirically under various wind conditions. The results indicate that the wave characteristics become practically independent of fetch after 200 to 300 miles, and that in the equilibrium condition the steepness of the highest waves is inversely proportional to the square root of the wind speed. Some theoretical foundation can be found for the form of the empirical relationships if it is assumed that the wind acts on each wave component independently, and that the sheltering coefficient used by Jeffreys is proportional to the wave steepness. The results provide a basis for making reasonably accurate predictions of waves and swell from meteorological charts and forecasts.

scholarly journals Wave Transformation for International Hub Port Planning (Transformasi Gelombang untuk Perencanaan Pelabuhan Hub Internasional)

2015 ◽  
Vol 20 (1) ◽  
pp. 9
Author(s):  
Denny Nugroho Sugianto ◽  
Purwanto Purwanto ◽  
Andika B Candra
Keyword(s):  
Wave Height ◽  
Vital Role ◽  
Ocean Wave ◽  
Wave Transformation ◽  
Wave Refraction ◽  
Wave Characteristics ◽  
Maximum Period ◽  
Wave Patterns ◽  
Port Planning ◽  
North Sumatra

Indonesia merupakan salah satu negara kepulauan terbesar di dunia sehingga peran pelabuhan sangat vital dalam pembangunan ekonomi. Pelabuhan bukan hanya sekedar sebagai pelengkap infrastruktur, melainkan harus direncanakan dan dikelola dengan baik serta memperhatikan fenomena dinamika perairan laut seperti pola gelombang laut. Data gelombang laut menjadi faktor penting dalam perencanaan tata letak dan tipe bangunan pantai karena dipengaruhi oleh tinggi gelombang signifikan, tunggang pasang surut dan transformasi gelombang. Penelitian ini mengalisis karaketristrik dan bentuk transformasi gelombang untuk perencanaan Pelabuhan Hub Internasional, sebagai studi kasus adalah pelabuhan di Kuala Tanjung, Kabupaten Batu Bara. Pelabuhan di Kuala Tanjung merupakan salah satu dari 2 pelabuhan hub internasional yang direncanakan akan dibangun oleh pemerintah Indonesia. Metode yang digunakan adalah metode kuantitatif yang dilakukan dengan perhitungan statistik dan pemodelan matematik dengan modul hydrodinamic dan spectral wave untuk mengetahui arah penjalaran dan transformasi gelombang. Hasil dari data ECMWF selama 1999–Juni 2014, diketahui tinggi gelombang signifikan (Hs) maksimum mencapai 1,69 m dan periode maksimum 8 detik. Karakteristik gelombang termasuk klasifikasi gelombang laut transisi dengan nilai d.L-1 berkisar anrata 0,27–0,48 dan berdasarkan periodenya diklasifikasikan sebagai gelombang gravitasi.Transformasi gelombang terjadi akibat pendangkalan dengan koefesian pendangkalan Ks 0,93–0,98 dan proses refraksi gelombang dengan koefesien Kr 0,97–0,99. Tinggi gelombang pecah Hb sebesar 1,24 meter dengan kedalaman gelombang pecah db sebesar 1,82 meter. Efektifitas desain bangunan terminal di Pelabuhan Kuala Tanjung secara keseluruhan untuk sepanjang musim sebesar 79,8% atau dapat dikatakan cukup efektif dalam meredam gelombang. Kata kunci: transformasi gelombang, tinggi dan periode gelombang, pelabuhan Indonesia is one of the largest archipelagic countries in the world, therefore port has vital role in economic development. Port is not just as a complement to the infrastructure, but it must be planned and managed properly and attention to the dynamics of marine phenomena such as ocean wave patterns. Ocean wave data become important factors in planning coastal building, since it is influenced by wave height, tides and waves transformation. The purpose of this study was to analyse characteristic and forms wave transformations for planning of international hub port at Kuala Tanjung, Baru Bara District North Sumatra. This port is one of two Indonesian government's plan in the development of international hub port. Quantitative method was used in this study by statistical calculations and mathematical modeling with hydrodinamic modules and spectral wave to determine the direction of wave propagation and transformation. Results show that based on ECMWF data during 1999-June 2014, known significant wave height (Hs) maximum of 1.69 m and maximum period (Ts) of 8 secs. The classification wave characteristics iswave transition (d.L-1: 0.27–0.48) and by the period are classified as gravitational waves. Wave transformation occurs due to the soaling, withKs 0.93–0.98 and the wave refraction Kr 0.97–0.99. Whereas Hb of 1.24 meters anddb 1.82 meters. The effectiveness of the design of the terminal building at the Port of Kuala Tanjung overall for the season amounted to 79.8%, which is quite effective in reducing the wave. Keywords: wave transformation, wave height and period, Port of Kuala Tanjung

scholarly journals PROBABILITIES OF BREAKING WAVE CHARACTERISTICS

1970 ◽  
Vol 1 (12) ◽  
pp. 25 ◽  
Author(s):  
J. Ian Collins
Keyword(s):  
Shallow Water ◽  
Probability Density ◽  
Deep Water ◽  
Surf Zone ◽  
Probability Distributions ◽  
Rayleigh Distribution ◽  
Breaking Wave ◽  
Wave Characteristics ◽  
Probability Densities ◽  
Wave Heights

Utilizing the hydrodynamic relationships for shoaling and refraction of waves approaching a shoreline over parallel bottom contours a procedure is developed to transform an arbitrary probability density of wave characteristics in deep water into the corresponding breaking characteristics in shallow Water A number of probability distributions for breaking wave characteristics are derived m terms of assumed deep water probability densities of wave heights wave lengths and angles of approach Some probability densities for wave heights at specific locations in the surf zone are computed for a Rayleigh distribution in deep water The probability computations are used to derive the expectation of energy flux and its distribution.

The Offshore Wave Simulation Based on the Improved P-M Spectrum and Multiple Fractal Interpolation

2014 ◽  
Vol 1030-1032 ◽  
pp. 1832-1836
Author(s):  
Ying Li ◽  
Rui Zhou ◽  
Hao Kuan Li ◽  
Ming Wang
Keyword(s):  
Shallow Water ◽  
Interpolation Method ◽  
Fractal Interpolation ◽  
Fractal Method ◽  
Growth State ◽  
Water Factor ◽  
Proposed Model ◽  
Simulation Based ◽  
Offshore Wave ◽  
The Waves

The Pierson - Moskowitz model is only applicable to full growth state of the waves, and it has low authenticity and hopping phenomenon under the condition of offshore shallow water. This paper proposes a simulation model of offshore wave based on the improved P-M spectrum and multiple fractal interpolation methods. In order to calculate the sea wave with shallow water, a spectrum peak regulation factor and a depth of the water factor are introduced to the P - M spectrum model. Based on this model, the wavelength and wave speed are used as the initial values of wave height. Then, the amplitude and the number of iterations in diamond square fractal method are controlled to obtain the fractal static sea. In order to reduce the influence of the hopping phenomenon to the simulation authenticity, meanwhile, a multiple dynamic non-uniform interpolation method is proposed. The experimental results show that the proposed model can simulate offshore wave with better effect and in real time.

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