EXCITATION OF THE SEICHE BY THE WIND YOSHIOKA, Hiroshi; MURAYAMA, Hidetoshi; TAKAYAMA, Tomotsuka ...
PROCEEDINGS OF CIVIL ENGINEERING IN THE OCEAN,
2003, Volume:
19
Journal Article
Open access
The long period oscillation (LPO) with high amplitude (1m) and short period (<5min.) was observed at Shimohaya Bay in Wakayama Prefecture in a storm. The sea wind gustiness and wave group observed at ...the offshore area had the nearly same period of the LPO. We had the numerical simulation of the LPO assuming that LPO is generated by only wind gustiness. The results show good agreement with observed LPO qualitatively (East wind with 6 minute oscillation generate big LPO only in Shimohaya-Bay). But the amplitude of calculated LPO is less than 10% of observed one.
This paper describes the motion characteristics as the Large-Scale Floating Coal Transshipment Station (LFTS) System considering the effects by motion of LFTS and large bulker. Because the topography ...of the seabed near East Kalimantan Island, Indonesia's main coal production area, is shallow, it is difficult for bulk carriers to reach the coast. Therefore, LFTS is proposed, which will be used as a relay base between coal-barging barges from land and bulk carriers offshore. However, LFTS and bulker are both large structures, and their motion are considered to affect each other through mooring ropes. Also, LFTS is affected by long-period wave drifting force. Therefore, grasping the motion characteristics of the LFTS system consisting of LFTS and bulker will be a very important issue for its realization. And then, in this study, the characteristics of the movement response of the LFTS system were also considered, which also considered the influence of the movement of the two floating bodies of LFTS and bulker on the movement response of each other through the mooring rope.
The effect of long period oscillation (LPO) is usually neglected for storm surge prediction because it is hidden behind high waves. We observed a big LPO (amplitude was about 0.5m and period was ...about 5 minute) at Shimohaya Bay in Wakayama Prefecture in a storm. The LPO in storm surge condition would raise the water level of 0.5m, which causes the increase of wave overtopping and wave force on coastal structures. Power spectra of wind and wave group were compared with that of LPO. Periods of around 5 minutes are predominant in sea wind and wave group, and they are sameas the resonance period of Shimohaya Bay.
This paper describes the motion characteristics and cargo handling efficiency of the Large-Scale Floating Coal Transshipment Station (LFTS). In considering feasibility of the LFTS system, it is ...important to know the cargo handling operation rate in the target area. LFTS can load 500,000 tons of coal and the draft will fluctuate greatly depending on the loading condition of coal. Accordingly, it is conceivable that wind load and the wave force including the slowly varying wave drift force affect the fluctuation greatly affect the fluctuation. Also, LFTS and bulk carrier are large-scale structures, the fluid forces acting on both affect each other, so the influence of hydrodynamic mutual interference between two floating bodies cannot be ignored. In this study, Grasp the motion response of bulk carrier under composite external force considering influence of hydrodynamic mutual interference, Based on the results, cargo handling efficiency was calculated, and the operating status of the LFTS system was grasped.
Long-period wave problem is selected as the theme of the special session on the design and the construction of maritimes tructures. Firstly, the basic properties of the long-period waves, such as the ...generation and propagation of long-period waves, the engineering problems on those and the countermeasures against the long-period wave problem, and its reflection on the design maritime structure at present are lectured. The panel discussion for the reflection of long-period waves on the design of maritime structures was opened. The practical problems in the design stage and the direction of the future research on the long-period waves were discussed.
The long-period waves have been researched in recent years because of its importance in the various problems of coastal engineering, such as long-period oscillation, long-period motions of moored ...vessels, sediment transport, wave-overtopping and stability of coastal structures. Importance of long period waves have been well recognized, however, its reflection of effects of the long-period waves into design of coastal facilities is not sufficient. In this paper, we review previous researches on the long period waves and consider the problems in the reflection of effects of long-period waves into design of coastal facilities.
It is important in berth planning and port operation to be accurately familiar with moored ship motions correctly in especially long period component, especially at ports facing the open sea. The ...phenomenon of moored ship oscillations has been studied for decades by model experiments, field observations and numerical simulations. This paper shows the comparison of numerical simulation result and field observations to discuss how we get more accurate result by the numerical simulations on ship motions. Major unknown factors for surging in the numerical simulations are the condition of mooring ropes and damping factor. Then, we discuss on the effect of the characteristics of mooring system and surge damping factor.
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