scholarly journals SUBHARMONIC GENERATION OF TRANSVERSE OSCILLATIONS INDUCED BY INCIDENT REGULAR WAVES

2012 ◽  
Vol 1 (33) ◽  
pp. 11 ◽  
Author(s):  
Gang Wang ◽  
Jin-Hai Zheng
Keyword(s):  
Numerical Investigation ◽  
Incident Wave ◽  
Growth Rates ◽  
Wave Amplitude ◽  
Threshold Value ◽  
Steep Slope ◽  
Regular Waves ◽  
Constant Slope ◽  
Incident Waves ◽  
Transverse Oscillations

It is generally accepted that there are transverse oscillation, which are concentrated and confined to the backwall and decay asymptotically offshore, existed in the harbor of constant slope, however, whether these oscillations can be induced by the normally incident waves is not clear. This numerical investigation aims at providing the subharmonic generations of transverse oscillations within the harbor of a plane slope by waves normally impacting on. For the harbor of perfectly plane slopes, the subharmonic transverse oscillations are small on the mild and moderate slopes but evident on the steep slope. This instability can take place only if the incident wave amplitude exceeds a threshold value, and transverse oscillations can even grow up to a larger value than that of longitudinal oscillations. The magnitudes of transverse oscillations are approximately the same, only their growth rates are affected by the incident wave amplitude.

scholarly journals Dasar Laut Sinusoidal Sebagai Reflektor Gelombang

2011 ◽  
Vol 2 (1) ◽  
pp. 441
Author(s):  
Viska Noviantri
Keyword(s):  
Asymptotic Expansion ◽  
Incident Wave ◽  
Large Amplitude ◽  
Wave Amplitude ◽  
Transmitted Wave ◽  
Bragg Resonance ◽  
Multi Scale ◽  
Reflected Wave ◽  
Incident Waves

This article discusses about the influence of sinusoidal sandbars towards the amplitude of incident wave. sinusoidal sandbars may lead to Bragg resonance. Basically, when a wave meets a different depth, it will scatter into a transmitted wave and a reflected wave. Bragg resonance happens when the wavelength of incident wave is twice of the wavelength of the periodic bottom disturbance. We apply the multi-scale asymptotic expansion to obtain the results. Eventually we find that a larger amplitude disturbance leads to larger reflected wave amplitude. This result explains that the sinusoidal sandbars indeed can reduce the amplitude of incident wave and protect a beach from large amplitude incident waves. 

Damping of Regular Waves in Model Ice

2020 ◽  
Author(s):  
Moritz C. N. Hartmann ◽  
R. U. Franz von Bock und Polach ◽  
Marco Klein
Keyword(s):  
Dispersion Relation ◽  
Water Waves ◽  
Wave Amplitude ◽  
Wave Length ◽  
Open Water ◽  
Angular Frequency ◽  
Wave Number ◽  
Regular Waves ◽  
Incident Waves ◽  
The Waves

Abstract Wave characteristics change significantly when the waves propagate in a solid ice field. The damping of the incident waves due to the presence of the ice sheet has a significant impact on the modification of wave propagation and dispersion. In this study the interaction of waves with solid ice are investigated by means of model tests. The objective of the study is to measure wave and ice characteristics and analyze the data regarding wave damping and the change of wave parameters in model ice. The experiments were performed in the ice tank of the Hamburg ship model basin (HSVA) with a set of regular waves with varying wave number and steepness. The surface elevation of the waves is recorded by acoustic and motion capturing measurement devices. By comparing the measurements of the incident open water waves with the waves in ice, the change in terms of wave amplitude and dispersion due to the presence of ice is analyzed. It is shown that once the waves travels through the ice the angular frequency remains unchanged while the wave amplitude exponentially decays, with an increasing decay coefficient at smaller wave length. Furthermore, the dispersion relation in ice, represented by the measured angular frequency and wave number, is consistent with the theoretical dispersion relation.

Numerical experiments on transverse oscillations induced by normal-incident waves in a rectangular harbor of constant slope

2013 ◽  
Vol 57 ◽  
pp. 1-10 ◽  
Author(s):  
Gang Wang ◽  
Jin-Hai Zheng ◽  
Jerome Peng-Yea Maa ◽  
Ji-Sheng Zhang ◽  
Ai-Feng Tao
Keyword(s):  
Numerical Experiments ◽  
Constant Slope ◽  
Incident Waves ◽  
Transverse Oscillations

Study on Nonlinear Motion Behavior of Coupled Heave-Pitch for the Classic Spar Platform Based on AQWA

2012 ◽  
Vol 170-173 ◽  
pp. 2170-2174 ◽  
Author(s):  
Song Sang ◽  
Yuan Zhou ◽  
Xue Liang Jiang
Keyword(s):  
Incident Wave ◽  
Wave Amplitude ◽  
Wave Period ◽  
Critical Periods ◽  
Spar Platform ◽  
Natural Period ◽  
Nonlinear Motion ◽  
Motion Characteristic ◽  
Instability Parameter ◽  
Motion Behavior

This paper used AQWA software to research the nonlinear motion characteristic of heave-pitch coupling of classical Spar platform in regular waves. With classic Spar platform as an example, the wave amplitude and periodic changes’ effect to the nonlinear motion behavior of coupled heave-pitch is researched. After calculation, the critical periods corresponding to the different incident wave amplitude are obtained, based which, gets the instability parameter domain of coupling resonance of platform in the wave period-amplitude plane. The results in this paper show that the heave-pitch coupled resonance of platform depends on the wave amplitude and the ratio of the natural period of heave and pitch, and the incident wave period.

The Stochastic Parametric Mechanism for Growth of Wind-Driven Surface Water Waves

2008 ◽  
Vol 38 (4) ◽  
pp. 862-879 ◽  
Author(s):  
Brian F. Farrell ◽  
Petros J. Ioannou
Keyword(s):  
Surface Water ◽  
Growth Rates ◽  
Atmospheric Pressure ◽  
Water Waves ◽  
Wave Amplitude ◽  
Pressure Fluctuations ◽  
Theoretical Understanding ◽  
Wave Growth ◽  
Atmospheric Pressure Fluctuations ◽  
Surface Water Waves

Abstract Theoretical understanding of the growth of wind-driven surface water waves has been based on two distinct mechanisms: growth due to random atmospheric pressure fluctuations unrelated to wave amplitude and growth due to wave coherent atmospheric pressure fluctuations proportional to wave amplitude. Wave-independent random pressure forcing produces wave growth linear in time, while coherent forcing proportional to wave amplitude produces exponential growth. While observed wave development can be parameterized to fit these functional forms and despite broad agreement on the underlying physical process of momentum transfer from the atmospheric boundary layer shear flow to the water waves by atmospheric pressure fluctuations, quantitative agreement between theory and field observations of wave growth has proved elusive. Notably, wave growth rates are observed to exceed laminar instability predictions under gusty conditions. In this work, a mechanism is described that produces the observed enhancement of growth rates in gusty conditions while reducing to laminar instability growth rates as gustiness vanishes. This stochastic parametric instability mechanism is an example of the universal process of destabilization of nearly all time-dependent flows.

Diffraction Waves About an Advancing Wedge Model in Deep Water

1990 ◽  
Vol 34 (02) ◽  
pp. 105-122
Author(s):  
Hideaki Miyata ◽  
Makoto Kanai ◽  
Noriaki Yoshiyasu ◽  
Yohichi Furuno
Keyword(s):  
Numerical Simulation ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Wedge Angle ◽  
Wave Pattern ◽  
Regular Waves ◽  
Nonlinear Characteristics ◽  
Diffracted Waves ◽  
Nonlinear Features ◽  
Incident Waves

The diffraction of regular waves by advancing wedge models is studied both experimentally and numerically. The nonlinear features of diffracted waves are visualized by wave pattern pictures and the formation is analyzed by the grid-projection method. The experimental observation indicates that the diffracted waves have a number of nonlinear characteristics similar to shock waves due to the interaction of incident waves with the advancing obstacle in the flow-field caused by the advancing motion. Bow waves of both oblique type and normal detached type are observed at remarkably lower Froude numbers than in the case of a ship in steady advance motion. Their occurrence systematically depends on the Froude number and the wedge angle. The numerical simulation of this phenomenon by a finite-difference method shows approximate agreement with the experimental results.

scholarly journals GROIN LENGTH AND THE GENERATION OF EDGE WAVES

1976 ◽  
Vol 1 (15) ◽  
pp. 85 ◽  
Author(s):  
Michael K. Gaughan ◽  
Paul D. Komar
Keyword(s):  
Incident Wave ◽  
Wave Length ◽  
Critical Length ◽  
Beach Erosion ◽  
Rip Currents ◽  
Edge Waves ◽  
Normal Waves ◽  
Wave Basin ◽  
Incident Waves ◽  
Selection Of

A series of wave basin experiments were undertaken to better understand the selection of groin spacings and lengths. Rather than obtaining edge waves with the same period as the normal incident waves, subharmonic edge waves were produced with a period twice that of the incoming waves and a wave length equal to the groin spacing. Rip currents were therefore not formed by the interactions of the synchronous edge waves and normal waves as proposed by Bowen and Inman (1969). Rips were present in the wave basin but their origin is uncertain and they were never strong enough to cause beach erosion. The generation of strong subharmonic edge waves conforms with the work of Guza and Davis (1974) and Guza and Inman (1975). The subharmonic edge waves interacted with the incoming waves to give an alternating sequence of surging and collapsing breakers along the beach. Their effects on the swash were sufficient to erode the beach in some places and cause deposition in other places. Thus major rearrangements of the sand were produced between the groins, but significant erosion did not occur as had been anticipated when the study began. By progressively decreasing the length of the submerged portions of the groins, it was found that the strength (amplitude) of the edge waves decreases. A critical submerged groin length was determined whereby the normally incident wave field could not generate resonant subharmonic edge waves of mode zero with a wavelength equal to the groin spacing. The ratio of this critical length to the spacing of the groins was found in the experiments to be approximately 0.15 to 0.20, and did not vary with the steepness of the normal incident waves.

Numerical investigation of oscillations induced by submerged sliding masses within a harbor of constant slope

2017 ◽  
Vol 63 ◽  
pp. 49-64 ◽  
Author(s):  
Dong Shao ◽  
Xi Feng ◽  
Weibing Feng ◽  
Guangwen Hong
Keyword(s):  
Numerical Investigation ◽  
Constant Slope

scholarly journals BEACH PROFILES AT TORREY PINES, CALIFORNIA

1976 ◽  
Vol 1 (15) ◽  
pp. 75 ◽  
Author(s):  
David G. Aubrey ◽  
Douglas L. Inman ◽  
Charles E. Nordstrom
Keyword(s):  
Sediment Transport ◽  
Incident Wave ◽  
Wave Energy ◽  
Energy Conditions ◽  
Beach Profile ◽  
High Wave ◽  
Wave Characteristics ◽  
Spectral Estimates ◽  
High Wave Energy ◽  
Incident Waves

Beach profiles have been measured at Torrey Pines Beach, California for four years and correlated with tides and accurate spectral estimates of the incident wave field. Characteristic equilibrium beach profiles persist for time spans of up to at least two weeks in response to periods of uniform incident waves. These changes in the beach profiles are primarily due to on-offshore sediment transport which can be related to variations in wave characteristics and tidal phase. The most rapid readjustment of the beach profile occurs during high wave energy conditions coincident with spring tides. Alternatively, the highest berm building is associated with moderate to low waves that coincide with spring tides.

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