Experimental investigation of turbulence generated by breaking waves in water of intermediate depth

In impacts of breaking waves on offshore structures, it is still not well-known how the air entrainment phenomenon affects the exerted loads. In this paper, a developed CFD solver capable of simulating the air entrainment process was employed to reproduce an experimental investigation on the impact of a spilling wave against a circular cylinder. The exerted in-line force was computed with and without the inclusion of dispersed bubbles. Results showed that the magnitude of the computed force was affected when the entrainment of bubbles was simulated.

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EXPERIMENTAL INVESTIGATION OP SHOCK PRESSURES AGAINST BREAKWATERS

Coastal Engineering Proceedings ◽

10.9753/icce.v11.62 ◽

1968 ◽

Vol 1 (11) ◽

pp. 62 ◽

Cited By ~ 5

Author(s):

Gustaf Richert

Keyword(s):

Experimental Investigation ◽

Wave Front ◽

Water Depth ◽

Test Procedure ◽

Breaking Waves ◽

Pressure Variation ◽

Shock Pressure ◽

Compression And Expansion ◽

Air Cushion ◽

Special Respect

This paper describes an experimental investigation of shock pressures against breakwaters caused by "breaking waves. The study only considers shocks of a compressive type, which occur if the wave front is formed in such a way that an air cushion is entrapped between the wave and the wall. In this case the compression and expansion of the air cushion plays an important role m the pressure variation. Only waves preceded by non-breaking waves were used. For different combinations of bottom geometry and water depth the occurrence of shock pressures of different magnitudes was studied varying the wave height and the wave period. For some interesting combinations of bottom geometry and wave dimensions a series of tests were made to investigate the distribution over the wall of shock pressure and of shock impulse. The results, presented m diagrams and tables, have been commented on and analysed with special respect to the chosen test procedure.

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A Novel Method for Generating Continuously Surfable Waves: Comparison of Predictions With Experimental Results

Volume 6: Ocean Engineering ◽

10.1115/omae2011-49145 ◽

2011 ◽

Cited By ~ 1

Author(s):

Steven A. Schmied ◽

Jonathan R. Binns ◽

Martin R. Renilson ◽

Giles A. Thomas ◽

Gregor J. Macfarlane ◽

...

Keyword(s):

Energy Efficiency ◽

Experimental Investigation ◽

Wave Breaking ◽

Breaking Waves ◽

Experimental Results ◽

Pressure Source ◽

Towing Tank ◽

Novel Method ◽

The Waves

In this paper, a novel idea to produce continuous breaking waves is discussed, whereby a pressure source is rotated within an annular wave pool. The concept is that the inner ring of the annulus has a sloping bathymetry to induce wave breaking from the wake of the pressure source. In order to refine the technique, work is being conducted to better understand the mechanics of surfable waves generated by moving pressure sources in restricted water. This paper reports on the first stage of an experimental investigation of a novel method for generating continuously surfable waves utilising a moving pressure source. The aim was to measure and assess the waves generated by two parabolic pressure sources and a wavedozer [1] for their suitability for future development of continuous breaking surfable waves. The tests were conducted at the Australian Maritime College (AMC), University of Tasmania (UTas) 100 metre long towing tank. The experimental results as variations in wave height (H) divided by water depth (h) as functions of depth Froude number (Frh) and h, together with predictions from both methods, are presented in this paper. Finally, measures of the wave making energy efficiency of each pressure source, and the surfable quality of the waves generated by it, were developed and are presented.

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Experimental investigation for characteristics of wave impact loads on a vertical cylinder in breaking waves

Ocean Engineering ◽

10.1016/j.oceaneng.2020.107470 ◽

2020 ◽

Vol 209 ◽

pp. 107470

Author(s):

Yoon-Jin Ha ◽

Kyong-Hwan Kim ◽

Bo Woo Nam ◽

Sa Young Hong

Keyword(s):

Experimental Investigation ◽

Vertical Cylinder ◽

Breaking Waves ◽

Impact Loads ◽

Wave Impact

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On a unified breaking onset threshold for gravity waves in deep and intermediate depth water

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.93 ◽

2018 ◽

Vol 841 ◽

pp. 463-488 ◽

Cited By ~ 34

Author(s):

X. Barthelemy ◽

M. L. Banner ◽

W. L. Peirson ◽

F. Fedele ◽

M. Allis ◽

...

Keyword(s):

Water Waves ◽

Wave Packets ◽

Fluid Velocity ◽

Bottom Topography ◽

Breaking Waves ◽

Wave Crest ◽

Intermediate Depth ◽

Local Ratio ◽

2D And 3D ◽

Depth Water

We revisit the classical but as yet unresolved problem of predicting the breaking onset of 2D and 3D irrotational gravity water waves. Based on a fully nonlinear 3D boundary element model, our numerical simulations investigate geometric, kinematic and energetic differences between maximally tall non-breaking waves and marginally breaking waves in focusing wave groups. Our study focuses initially on unidirectional domains with flat bottom topography and conditions ranging from deep to intermediate depth (depth to wavelength ratio from 1 to 0.2). Maximally tall non-breaking (maximally recurrent) waves are clearly separated from marginally breaking waves by their normalised energy fluxes localised near the crest tip region. The initial breaking instability occurs within a very compact region centred on the wave crest. On the surface, this reduces to the local ratio of the energy flux velocity (here the fluid velocity) to the crest point velocity for the tallest wave in the evolving group. This provides a robust threshold parameter for breaking onset for 2D wave packets propagating in uniform water depths from deep to intermediate. Further targeted study of representative cases of the most severe laterally focused 3D wave packets in deep and intermediate depth water shows that the threshold remains robust. These numerical findings for 2D and 3D cases are closely supported by our companion observational results. Warning of imminent breaking onset is detectable up to a fifth of a carrier wave period prior to a breaking event.

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Dynamic Knockdown of Canting Keel Yachts in Breaking Waves

Marine Technology and SNAME News ◽

10.5957/mtsn.2009.46.2.99 ◽

2009 ◽

Vol 46 (02) ◽

pp. 99-106

Author(s):

Jonathan R. Binns ◽

Oscar Palos ◽

Paul Brandner ◽

Giles Thomas

Keyword(s):

Experimental Investigation ◽

Dynamic Stability ◽

Stability Index ◽

Breaking Waves ◽

Experimental Results ◽

Towing Tank ◽

Video Cameras ◽

Regulatory Authorities ◽

Righting Moment

Yacht canting keel configurations have been developed to maximize the available righting moment by rotating their keel bulb to windward. Regulatory authorities have been required to establish rules covering the design and operation of such systems; however, significant dynamic investigations into their behavior have not been performed. This paper presents results from a theoretical and experimental investigation into the dynamic stability of canting keel sailing yachts when experiencing a knockdown by large breaking waves. Towing tank experiments were conducted on a yacht model with a fixed keel and two canted keel configurations, beam-on to large solitary breaking waves. The motion of the model during the tests was recorded by four video cameras and analyzed using photogrammetry. A comparison of the hydrostatic predictions and experimental results indicate that the traditional GZ approach of assessing the energy required to heel may not be appropriate for yachts with canting keels. In addition, a correlation of the experimental results with the ISO stability index highlights that this index may be unsuitable for categorizing yachts with canting keels with respect to their ability to recover after a knockdown event.

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