Damping Effect of Floating Breakwater to Which Anti-Rolling System is Applied

This paper deals experimentally with combinations of the pneumatic breakwater and other type breakwaters in order to increase the effectiveness of wave damping. Firstly, a submerged breakwater is picked up, and the wave damping effect of this combined type breakwater is examined. Results obtained in this experiment show that some improvements on the wave damping are found for low frequency waves that cannot be damped by the pneumatic breakwater only. The reason of appearence of the combination effect is explained that a part of energy of the transmitted waves over the submerged breakwater transfers to shorter period waves. Secondly, a floating breakwater is combined with the pneumatic breakwater. Experiments show that the transmission factor for high frequency waves becomes smaller than that of the pneumatic breakwater only, while there is not so much wave damping effect for low frequency waves even when the floating breakwater is combined. In addition, a guide plate is set below the bottom of the floating breakwater in order to increase the horizontal flow velocity for a given air discharge. It is found that the velocity of horizontal surface flow by using the guide plate increases as much as about 1.3 times that in the case of the pneumatic breakwater only. As a result, a little improvement on the wave damping due to the guide plate is also found.

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ON THE FLOATING BREAKWATER - A NEW ARRANGEMENT

Coastal Engineering Proceedings ◽

10.9753/icce.v20.148 ◽

1986 ◽

Vol 1 (20) ◽

pp. 148

Author(s):

C.H. Lee ◽

S.W. Twu

Keyword(s):

Wave Damping ◽

Model Studies ◽

Damping Effect ◽

Floating Breakwater ◽

New Type ◽

The One ◽

Better Than

A new type of floating breakwater composed of net-tubes and buoy-balls is presented in this paper. A series of model studies have been carried out for several arrangements of this structure. As wave damping effect is concerned, a case that the structure being set vertically is shown to be better than the one being set horizontally, while more than two rows of the structures are set vertically and separately, a case which being connected with ropes between adjoining rows is proved to be better than the case without connecting ropes.

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Damping Effect of Floating Breakwater

Journal of the Waterways and Harbors Division ◽

10.1061/jwheau.0000648 ◽

1969 ◽

Vol 95 (3) ◽

pp. 337-344

Author(s):

Juichi Kato ◽

Toshifumi Noma ◽

Yukio Uekita ◽

Seiya Hagino

Keyword(s):

Damping Effect ◽

Floating Breakwater

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DAMPING EFFECT OF FLOATING BREAKWATER TO WHICH ANTI-ROLLING SYSTEM IS APPLIED

Coastal Engineering Proceedings ◽

10.9753/icce.v10.62 ◽

1966 ◽

Vol 1 (10) ◽

pp. 62

Author(s):

Juichi Kato ◽

Seiya Hagino ◽

Yukio Uekita

Keyword(s):

Water Surface ◽

Sea Water ◽

Natural Oscillation ◽

Oscillation Period ◽

Floating Body ◽

Fishing Ground ◽

Water Volume ◽

Fish Farms ◽

Damping Effect ◽

Floating Breakwater

Among the recent problems in the fisheries in Japan, the development of fish farms is getting to be important. The breakwater for fish farms is required to have the functions of exchanging sea water and the preservation of fishing ground, as well as the outer facilities of finning ground.. Various types of breakwater to meet the requirements can be considered,the floating breakwater being one of them. When we limit the studies in the wave damping effect of a mobile breakwater, we can summarise that an effective floating breakwater should have sufficient draught under water surface and should have a comparatively large displaced water volume. In other words, the natural oscillation period of the floating body must be large enough as compared with that of the incident wave. (R. L.Wiegel '64) (K. Horikawa et al. '64) for practical purposes the studies on the shape and type must follow. However, if a floating breakwater is provided with a mechanism for attenuating wave, the above-mentioned criterion for the effectiveness must be largely changed.

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Design of a Pendulum-type Anti-rolling System for USSV and Verification Based on Roll Damping Coefficient

Journal of the Society of Naval Architects of Korea ◽

10.3744/snak.2019.56.6.550 ◽

2019 ◽

Vol 56 (6) ◽

pp. 550-558

Author(s):

Woo-Seok Jin ◽

Yong-Ho Kim ◽

Jun-Ho Jung ◽

Kwangkook Lee ◽

Dong-Hun Kim

Keyword(s):

Damping Coefficient ◽

Roll Damping ◽

Rolling System

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Representative Transmission Coefficient for Evaluating the Wave Attenuation Performance of 3D Floating Breakwaters in Regular and Irregular Waves

Journal of Marine Science and Engineering ◽

10.3390/jmse9040388 ◽

2021 ◽

Vol 9 (4) ◽

pp. 388

Author(s):

Huu Phu Nguyen ◽

Jeong Cheol Park ◽

Mengmeng Han ◽

Chien Ming Wang ◽

Nagi Abdussamie ◽

...

Keyword(s):

Transmission Coefficient ◽

Wave Height ◽

Wave Attenuation ◽

Transmitted Wave ◽

Irregular Waves ◽

Hydrodynamic Analysis ◽

Evaluation Approach ◽

Floating Breakwater ◽

Floating Breakwaters ◽

Evaluation Approaches

Wave attenuation performance is the prime consideration when designing any floating breakwater. For a 2D hydrodynamic analysis of a floating breakwater, the wave attenuation performance is evaluated by the transmission coefficient, which is defined as the ratio between the transmitted wave height and the incident wave height. For a 3D breakwater, some researchers still adopted this evaluation approach with the transmitted wave height taken at a surface point, while others used the mean transmission coefficient within a surface area. This paper aims to first examine the rationality of these two evaluation approaches via verified numerical simulations of 3D heave-only floating breakwaters in regular and irregular waves. A new index—a representative transmission coefficient—is then presented for one to easily compare the wave attenuation performances of different 3D floating breakwater designs.

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