• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.595-608
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• 2013

This paper is proposed the computation method of moored ship motion considering harbor resonance, and estimated that the harbor resonance have an effect on moored ship motion. The computation of harbor resonance was used CGWAVE model and the computation of moored sip motion was used the Green function method expressed by three dimensions. This method was verified with the field observation data of moored ship motion, and the application of actual harbor was investigated with wave field data and down time record data in Pohang New Harbor. The resonance periods in Pohang New Harbor that obtained from wave field data were 80, 33, 23, 8 minute, which are the long waves, and 42, 54, 60 second, which are the infra-gravity waves inside harbor slip. The simulated results of harbor resonance were corresponded with the wave field data. This study was investigated on 5,000 ton, 10,000 ton and 30,000 ton ship sized in Pier 8 of Pohang New Harbor that the harbor resonance has effect on moored ship motion from simulated results of ship motion in case of included resonance and excluded resonance. In case of included resonance, the ship motion have increased by 12~400 percent when compared with results of excluded resonance. We could find that the harbor resonance have still more an effect on the surge and heave motions of a large size ship and the roll and yaw motions of a small size ship.

• Selected Papers of The Society of Naval Architects of Korea
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• v.1 no.1
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• pp.4-14
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• 1993

A natural and an artificial harbor can exhibit frequency (or period) dependent water surface oscillations when excited by incident waves. Such oscillations in harbors can cause significant damages to moored ships and adjacent structures. This can also induce undesirable current in harbor. Many previous investigators have studied various aspects of harbor resonance problem. In the present paper, both a localized finite element method(LFEM) which is based on the functional constructed by Chen & Mei(1974) and Bai & Yeung(1974) and an integral equation method which was used by Lee(1969) are applied to harbor resonance problem. The LFEM shows computationally more efficient than the integral equation method. Our test results show a good agreement compared with other results. In the present computations, specifically two harbor geometris are treated here. The present method by LFEM can be extended to a fully three dimensional harbor problem.

• Bulletin of the Society of Naval Architects of Korea
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• v.25 no.3
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• pp.3-12
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• 1988

A natural or an artificial harbor can exhibit frequency(or period) dependent water surface oscillations when excited by incident waves. Such oscillations in harbors can cause significant damage to moored ships and adjacent structures. This can also induce undesirable current in harbors. Many previous investigators have studied various aspects of harbor resonance problem. In the percent paper, both a localizes finite element method(LFEM) which is based on the functional constructed by Chen & Mei(1974) and Bai & Yeung(1974) and an integral equation method which was used by Lee(1969) are applied to harbor resonance problem. The present method(LFEM) shows computationally more efficient than the integral equation method. Our test results shows good agreement compared with other results. This enhanced computational efficiency is due to the fact that the present method gives a banded symmetric coefficients matrix and requires much less computational time in the calculation of the influence coefficients matrix than the integral equation method involved with Green's function. To test the present numerical scheme, two models are treated here. The present method(LFEM) can be extended to a fully three dimensional harbor problem with the similar computational advantage.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.86-93
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• 2002

In this study, numerical experiments were performed to decide the proper size off finite element for the analysis of harbor resonance problems. Various sizes of finite elements were considered from 1/3 to 1/60 of wavelength to model a fully opened rectangular harbor. Through the numerical results, the proper number of finite elements per wavelength were revealed to be nine within two percents errors allowed in resonant period and amplification ratio, while twelve within one percent error. It was fecund that error rates of resonant periods decrease linearly, while those of amplification ratio decrease with oscillating form as the size of an element decreases. The error of amplification ratio increases more rapidly than that of resonant period in case of element numbers below nine.

• Ocean and Polar Research
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• v.25 no.spc3
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• pp.423-426
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• 2003

The seawater exchange breakwater equipped with an oscillating water channel and water transmitting pipes has a very spectacular function that seawater supply can be greatly increased due to the upsurge of the water surface inside the channel at resonance condition which can be reached when the incident wave period becomes close to the natural period of the channel. The variations of the water level and period inside the channel are very important factors in enhancing the efficiency of sea water exchange, especially when designing the breakwater cross-section in shallow water zone which requires longer resonance period with the elongated horizontal projection of the channel. In the present study, a hydraulic experiment was performed varying the length of the oscillating channel, and the resonance periods and water surface variations are analyzed in terms of water transmission through the pipes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.607-618
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• 1994

Effects of wave grouping on the harbor oscillation are studied in order to clarify the energy source of harbor resonance. The resonant periods of Donghae harbor and Imwon harbor are calculated using the boundary integral equation method. Also, the periods of the group-bounded long waves due to the irregular wave group are calculated using the theory developed in this study. Analyzing from the view point of period, it is concluded that the group-bounded long waves due to the irregular wave group can cause resonance in small harbors such as fishery harbors, and heavy ship motion in large harbors such as industrial ones.

• Journal of Ocean Engineering and Technology
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• v.5 no.1
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• pp.25-34
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• 1991

An accurate estimation of water level variation when thewaves propagate to the coastal regionis very important for the port and harbor development plan. This study describes the application of a hybrid element model to harbor oscillation problem due to the construction of shore structure and implementation of shore boundary. The site selected is Pusan Harbor area with the third development and the Artificial Island plan. The observed water level changes at the site are compared with the result of the numerical experiment. The model gives a very important prediction of water level changes for navigation and harbor design.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.2
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• pp.122-138
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• 2001

It is well known that whcn waves propagating on a shallow water suddenly encounter a much deeper water they do not propagate further but are reflected. If we apply this phenomenon to a harbor by making the harbor depth much greater than outside, we could improve the harbor tranquillity by making the waves impinging into the harbor be reflected at the harbor entrance. In the present paper, first we apply the numerical models based' on the mild-slope equation and extended mild-slope equation to calculate the long wave resonances in a rectangular harbor with a very large depth discontinuity at its entrance to find that the difference between the models is almost negligible. By applying the numerical model to a realistic model harbor whose inside is entirely dredged, it is found that the effect of dredging is insignificant when the inside depth is twice the outside one but tripled inside depth significantly reduces the long waves of period of one to five minutes whieh may exert a bad influence on ship motion. Moreover, even when only a portion of the harbor basin is dredged, the cffect of dredging in the dredged area is found to be comparable to that of entire dredging, showing that the dredging of harbor basin can be a countenncasure for harbor resonance.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2008.09a
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• pp.172-175
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• 2008

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2008.09b
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• pp.172-175
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• 2008