scholarly journals SHORT-CRESTED BREAKING WAVES

1984 ◽  
Vol 1 (19) ◽  
pp. 62
Author(s):  
P.C. Machen
Keyword(s):  
Experimental Data ◽  
Wave Height ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Water Particle ◽  
Model Scale

The likely effects of short-crested (sc) breaking waves on ships and structures are summarised in the case of the simplest non-trivial sc sea at medium/high crossing angle. Typical experimental data of sc breaking wave-height and sc water particle speeds are given at model-scale.

scholarly journals ENERGY LOSS AND SET-UP DUE TO BREAKING OF RANDOM WAVES

1978 ◽  
Vol 1 (16) ◽  
pp. 32 ◽  
Author(s):  
J.A. Battjes ◽  
J.P.F.M. Janssen
Keyword(s):  
Wave Height ◽  
Dissipation Rate ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Height Distribution ◽  
Random Waves ◽  
Dissipation Of Energy ◽  
Wave Height Distribution ◽  
Set Up ◽  
Local Depth

A description is given of a model developed for the prediction of the dissipation of energy in random waves breaking on a beach. The dissipation rate per breaking wave is estimated from that in a bore of corresponding height, while the probability of occurrence of breaking waves is estimated on the basis of a wave height distribution with an upper cut-off which in shallow water is determined mainly by the local depth. A comparison with measurements of wave height decay and set-up, on a plane beach and on a beach with a bar-trough profile, indicates that the model is capable of predicting qualitatively and quantitatively all the main features of the data.

Research and Analysis on the Wave Transformation and Irregular Wave Breaking Criterion on the Shore

2016 ◽  
Vol 858 ◽  
pp. 354-358
Author(s):  
Tao You ◽  
Li Ping Zhao ◽  
Zheng Xiao ◽  
Lun Chao Huang ◽  
Xiao Rui Han
Keyword(s):  
Theoretical Model ◽  
Wave Height ◽  
Wave Breaking ◽  
Surf Zone ◽  
Breaking Waves ◽  
Wave Transformation ◽  
Breaking Wave ◽  
Height Distribution ◽  
Flume Experiments ◽  
Irregular Wave

Within the surf zone which is the region extending from the seaward boundary of wave breaking to the limit of wave uprush, breaking waves are the dominant hydrodynamics acting as the key role for sediment transport and beach profile change. Breaking waves exhibit various patterns, principally depending on the incident wave steepness and the beach slope. Based on the equations of conservation of mass, momentum and energy, a theoretical model for wave transformation in and outside the surf zone was obtained, which is used to calculate the wave shoaling, wave set-up and set down and wave height distributions in and outside the surf zone. The analysis and comparison were made about the breaking point location and the wave height variation caused by the wave breaking and the bottom friction, and about the wave breaking criterion under regular and irregular breaking waves. Flume experiments relating to the regular and irregular breaking wave height distribution across the surf zone were conducted to verify the theoretical model. The agreement is good between the theoretical and experimental results.

scholarly journals Breaking-Wave Induced Transient Pore Pressure in a Sandy Seabed: Flume Modeling and Observations

2021 ◽  
Vol 9 (2) ◽  
pp. 160
Author(s):  
Changfei Li ◽  
Fuping Gao ◽  
Lijing Yang
Keyword(s):  
Pore Pressure ◽  
Wave Height ◽  
Wave Breaking ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Regular Waves ◽  
Large Wave ◽  
Pore Pressures ◽  
Linear Waves ◽  
Wave Induced

Previous studies on wave-induced pore pressure in a porous seabed mainly focused on non-breaking regular waves, e.g., Airy linear waves or Stokes non-linear waves. In this study, breaking-wave induced pore pressure response in a sandy seabed was physically simulated with a large wave flume. The breaking-wave was generated by superimposing a series of longer waves onto the foregoing shorter waves at a specified location. Water surface elevations and the corresponding pore pressure in the process of wave breaking were measured simultaneously at three typical locations, i.e., at the rear, just at, and in front of the wave breaking location. Based on test results, characterization parameters are proposed for the wave surface elevations and the corresponding pore-pressures. Flume observations indicate that the wave height was greatly diminished during wave breaking, which further affected the pore-pressure responses. Moreover, the measured values of the characteristic time parameters for the breaking-wave induced pore-pressure are larger than those for the free surface elevation of breaking-waves. Under the action of incipient-breaking or broken waves, the measured values of the amplitude of transient pore-pressures are generally smaller than the predicted results with the analytical solution by Yamamoto et al. (1978) for non-breaking regular waves with equivalent values of characteristic wave height and wave period.

scholarly journals WAVE SPECTRUM OF BREAKING WAVE

1976 ◽  
Vol 1 (15) ◽  
pp. 32 ◽  
Author(s):  
Toru Sawaragi ◽  
Koichiro Iwata
Keyword(s):  
Experimental Data ◽  
Wave Height ◽  
Power Law ◽  
Wave Breaking ◽  
Surf Zone ◽  
Wave Spectrum ◽  
Breaking Wave ◽  
Harmonic Frequency ◽  
Dimensional Consideration

By wave breaking, an incident monocromatic wave is transformed to a wave composed of its harmonic frequency waves inside a surf zone. Based on a dimensional consideration, the "-1 power law ", the "-2 power law ", the "-2/3 power law " and the "-1/2 power law " on the wave height spectrum ,H(f), are derived as sorts of equilibrium spectra. These spectra except"-l/2 power law" are shown to agree with experimental data.

scholarly journals EXPERIMENTAL RESULTS OF BREAKING WAVE IMPACT ON A VERTICAL WALL WITH AN OVERHANGING HORIZONTAL CANTILEVER SLAB

2011 ◽  
Vol 1 (32) ◽  
pp. 26
Author(s):  
Dogan Kisacik ◽  
Peter Troch ◽  
Philippe Van Bogaert
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
Vertical Wall ◽  
Breaking Waves ◽  
Wave Period ◽  
Breaking Wave ◽  
Wave Impact ◽  
Scaled Model ◽  
Physical Experiments ◽  
Horizontal Part

Physical experiments (at a scale of 1/20) are carried out using a vertical wall with horizontal cantilevering slab. Tests are conducted for a range of values of water depth, wave period and wave height. A parametric analysis of measured forces (Fh and Fv) both on the vertical and horizontal part of the scaled model respectively is conducted. The highest impact pressure and forces are measured in the case of breaking waves with a small air trap. Maximum pressures are measured around SWL and at the corner of the scaled model. The horizontal part of the scaled model is more exposed to impact waves than the vertical part. Fh and Fv are very sensitive for the variation of water depth (hs) and wave height (H) while variation of wave period (T) has a rather limited effect.

Bulk drag coefficient of a subaquatic vegetation subjected to irregular waves: Influence of Reynolds and Keulegan-Carpenter numbers

2020 ◽  
pp. 34-42
Author(s):  
Thibault Chastel ◽  
Kevin Botten ◽  
Nathalie Durand ◽  
Nicole Goutal
Keyword(s):  
Drag Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Empirical Relationship ◽  
Breaking Waves ◽  
Irregular Waves ◽  
Geometrical Parameters ◽  
Flume Experiments ◽  
Seagrass Meadows ◽  
Artificial Vegetation

Seagrass meadows are essential for protection of coastal erosion by damping wave and stabilizing the seabed. Seagrass are considered as a source of water resistance which modifies strongly the wave dynamics. As a part of EDF R & D seagrass restoration project in the Berre lagoon, we quantify the wave attenuation due to artificial vegetation distributed in a flume. Experiments have been conducted at Saint-Venant Hydraulics Laboratory wave flume (Chatou, France). We measure the wave damping with 13 resistive waves gauges along a distance L = 22.5 m for the “low” density and L = 12.15 m for the “high” density of vegetation mimics. A JONSWAP spectrum is used for the generation of irregular waves with significant wave height Hs ranging from 0.10 to 0.23 m and peak period Tp ranging from 1 to 3 s. Artificial vegetation is a model of Posidonia oceanica seagrass species represented by slightly flexible polypropylene shoots with 8 artificial leaves of 0.28 and 0.16 m height. Different hydrodynamics conditions (Hs, Tp, water depth hw) and geometrical parameters (submergence ratio α, shoot density N) have been tested to see their influence on wave attenuation. For a high submergence ratio (typically 0.7), the wave attenuation can reach 67% of the incident wave height whereas for a low submergence ratio (< 0.2) the wave attenuation is negligible. From each experiment, a bulk drag coefficient has been extracted following the energy dissipation model for irregular non-breaking waves developed by Mendez and Losada (2004). This model, based on the assumption that the energy loss over the species meadow is essentially due to the drag force, takes into account both wave and vegetation parameter. Finally, we found an empirical relationship for Cd depending on 2 dimensionless parameters: the Reynolds and Keulegan-Carpenter numbers. These relationships are compared with other similar studies.

scholarly journals Characteristics of Breaking Wave Forces on Piles over a Permeable Seabed

2021 ◽  
Vol 9 (5) ◽  
pp. 520
Author(s):  
Zhenyu Liu ◽  
Zhen Guo ◽  
Yuzhe Dou ◽  
Fanyu Zeng
Keyword(s):  
Wave Breaking ◽  
Stokes Equations ◽  
Slope Angle ◽  
Wave Force ◽  
Breaking Waves ◽  
Offshore Wind ◽  
Secondary Wave ◽  
Wave Forces ◽  
Breaking Wave ◽  
Breaking Wave Forces

Most offshore wind turbines are installed in shallow water and exposed to breaking waves. Previous numerical studies focusing on breaking wave forces generally ignored the seabed permeability. In this paper, a numerical model based on Volume-Averaged Reynolds Averaged Navier–Stokes equations (VARANS) is employed to reveal the process of a solitary wave interacting with a rigid pile over a permeable slope. Through applying the Forchheimer saturated drag equation, effects of seabed permeability on fluid motions are simulated. The reliability of the present model is verified by comparisons between experimentally obtained data and the numerical results. Further, 190 cases are simulated and the effects of different parameters on breaking wave forces on the pile are studied systematically. Results indicate that over a permeable seabed, the maximum breaking wave forces can occur not only when waves break just before the pile, but also when a “secondary wave wall” slams against the pile, after wave breaking. With the initial wave height increasing, breaking wave forces will increase, but the growth can decrease as the slope angle and permeability increase. For inclined piles around the wave breaking point, the maximum breaking wave force usually occurs with an inclination angle of α = −22.5° or 0°.

scholarly journals Influence of the Spatial Pressure Distribution of Breaking Wave Loading on the Dynamic Response of Wolf Rock Lighthouse

2021 ◽  
Vol 9 (1) ◽  
pp. 55
Author(s):  
Darshana T. Dassanayake ◽  
Alessandro Antonini ◽  
Athanasios Pappas ◽  
Alison Raby ◽  
James Mark William Brownjohn ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Pressure Distribution ◽  
Distinct Element ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Wave Loading ◽  
Wave Impact ◽  
Pressure Distributions ◽  
Impact Area ◽  
The Impact

The survivability analysis of offshore rock lighthouses requires several assumptions of the pressure distribution due to the breaking wave loading (Raby et al. (2019), Antonini et al. (2019). Due to the peculiar bathymetries and topographies of rock pinnacles, there is no dedicated formula to properly quantify the loads induced by the breaking waves on offshore rock lighthouses. Wienke’s formula (Wienke and Oumeraci (2005) was used in this study to estimate the loads, even though it was not derived for breaking waves on offshore rock lighthouses, but rather for the breaking wave loading on offshore monopiles. However, a thorough sensitivity analysis of the effects of the assumed pressure distribution has never been performed. In this paper, by means of the Wolf Rock lighthouse distinct element model, we quantified the influence of the pressure distributions on the dynamic response of the lighthouse structure. Different pressure distributions were tested, while keeping the initial wave impact area and pressure integrated force unchanged, in order to quantify the effect of different pressure distribution patterns. The pressure distributions considered in this paper showed subtle differences in the overall dynamic structure responses; however, pressure distribution #3, based on published experimental data such as Tanimoto et al. (1986) and Zhou et al. (1991) gave the largest displacements. This scenario has a triangular pressure distribution with a peak at the centroid of the impact area, which then linearly decreases to zero at the top and bottom boundaries of the impact area. The azimuthal horizontal distribution was adopted from Wienke and Oumeraci’s work (2005). The main findings of this study will be of interest not only for the assessment of rock lighthouses but also for all the cylindrical structures built on rock pinnacles or rocky coastlines (with steep foreshore slopes) and exposed to harsh breaking wave loading.

scholarly journals Physical Modelling of the Effect on the Wave Field of the WaveCat Wave Energy Converter

2021 ◽  
Vol 9 (3) ◽  
pp. 309
Author(s):  
James Allen ◽  
Gregorio Iglesias ◽  
Deborah Greaves ◽  
Jon Miles
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Significant Wave Height ◽  
Wedge Angle ◽  
Wave Energy Converter ◽  
Wave Period ◽  
Surface Elevation ◽  
Energy Converter ◽  
Significant Wave ◽  
Model Scale

The WaveCat is a moored Wave Energy Converter design which uses wave overtopping discharge into a variable v-shaped hull, to generate electricity through low head turbines. Physical model tests of WaveCat WEC were carried out to determine the device reflection, transmission, absorption and capture coefficients based on selected wave conditions. The model scale was 1:30, with hulls of 3 m in length, 0.4 m in height and a freeboard of 0.2 m. Wave gauges monitored the surface elevation at discrete points around the experimental area, and level sensors and flowmeters recorded the amount of water captured and released by the model. Random waves of significant wave height between 0.03 m and 0.12 m and peak wave periods of 0.91 s to 2.37 s at model scale were tested. The wedge angle of the device was set to 60°. A reflection analysis was carried out using a revised three probe method and spectral analysis of the surface elevation to determine the incident, reflected and transmitted energy. The results show that the reflection coefficient is highest (0.79) at low significant wave height and low peak wave period, the transmission coefficient is highest (0.98) at low significant wave height and high peak wave period, and absorption coefficient is highest (0.78) when significant wave height is high and peak wave period is low. The model also shows the highest Capture Width Ratio (0.015) at wavelengths on the order of model length. The results have particular implications for wave energy conversion prediction potential using this design of device.

Motion Characteristics of Composite-Type Sea Cage under Pure Wave

2012 ◽  
Vol 490-495 ◽  
pp. 3405-3409
Author(s):  
Chun Liu Li ◽  
Yun Peng Zhao
Keyword(s):  
Experimental Data ◽  
Wave Height ◽  
Vertical Motion ◽  
Data Acquisition System ◽  
Horizontal Motion ◽  
Wave Condition ◽  
Composite Type ◽  
Motion Range ◽  
Motion Characteristics ◽  
Sea Cage

To study motion range changes with wave condition and motion relationship between cages, physical model experiments were carried out. The authors designed 2 models of composite-type sea cages. Experimental data obtained by the CCD data acquisition system. The experiment results showed that 1.in the same period, horizontal motion range,vertical motion range and inclination changes of float collar increase with wave height; 2.In the same wave height, horizontal motion range of the float collar increases with period; 3.The laws between vertical motion and period are not obvious 4.The laws between inclination changes and period are not obvious 5.Motion range of the first cage along the direction of waves is less than other cages.

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