• Title/Summary/Keyword: motion characteristics in regular waves

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Motion Response Characteristics of Small Fishing Vessels of Different Sizes among Regular Waves

  • DongHyup Youn;LeeChan Choi;JungHwi Kim
    • Journal of Ocean Engineering and Technology
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    • v.37 no.1
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    • pp.1-7
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    • 2023
  • The motion of small fishing vessels is significantly affected by small waves, leading to accidents, such as capsizing or sinking. This paper presents the results of two types of basin tests. The first test analyzed the characteristics of roll and pitch motions among regular waves with the same wave steepness using the drifting state of three (3G/T, 7G/T, 10G/T) small fishing vessels. The second test analyzed the motion characteristics of the 7G/T fishing vessel under different wave steepness. The first test showed that heave and roll motions are significant in the beam sea, while pitch motion is significant in the bow and stern seas. The second test shows that wave steepness has a linear relationship with roll and pitch motions in the bow and stern seas.

Ship Motion and Propulsive Performance of a Container Ship in Regular Head Waves (콘테이너선의 피랑중 운동성능 저항증가 및 추진성능에 관한 연구)

  • Yang, Seung-Il;Kim, Eun-Chan;Hong, Seok-Won;Lee, Sang-Mu
    • 한국기계연구소 소보
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    • s.10
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    • pp.49-62
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    • 1983
  • A series of model tests on a container ship in waves was executed at the Experimental Towing Tank of Ship Research Station, KIMM. This paper presents the results of resistance, self-propulsion, propeller open-water and ship motion tests in regular head waves. Firstly, the experimental results of ship motion measured on a towed model and a self-propelled model were compared with those of Japanese results showing fairly good agreements. Secondly, the results of resistance and propulsion tests were analyzed and the data of added resistance, thrust increase, torque increase, revolution increase and self-propulsion factors in waves were presented. Also the diffraction force measured on a fixed model in waves was analyzed. Finally, this report shows the propeller characteristics in calm water based on propeller immersion and in regular waves based on wave length.

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An Experimental Analysis on the Motion Response of a Moored Semi-Submersible Platform in Regular Waves (계류된 반잠수식 시추선의 운동특성에 관한 실험적 고찰)

  • 홍사영;이판묵;홍도천
    • Journal of Ocean Engineering and Technology
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    • v.2 no.1
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    • pp.59-70
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    • 1988
  • This paper presents the results of motion tests of a moored semi-submersible platform in regular waves. To investigate the effects of mooring system on the motion characteristics, the tests were performed under the various mooring conditions in regular head and beam waves. Two types of mooring system were employed: one is composed of soft springs and the other is of chains. In the case of chains the pretensions were varied to investigate the dynamic effects of mooring forces as well as the motion responses of the semi-submersible. The motion responses and mooring tensions were measured and analyzed by the double amplitude method. The measured motion responses were also compared with the results of calculation from three-dimensional potential theory. Finally, the dynamic behaviors of mooring chains were studied.

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A numerical investigation on the nominal wake of KVLCC2 model ship in regular head waves

  • Shin, Hyun-Woo;Paik, Kwang-Jun;Jang, Yoon-Ho;Eom, Myeoung-Jin;Lee, Sungwook
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.12 no.1
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    • pp.270-282
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    • 2020
  • Analysis: of the propulsion performance considering ship motion in waves is an important factor for the efficient operation of a ship. The interaction between the propeller and the free surface due to the ship motion in waves has a significant influence on the propulsion performance. However, most recent studies regarding the hydrodynamic performance of ships in waves focus on the added resistance, and experimental and numerical data on the propulsion performance considering the ship motion in waves are very rare. In this study, a numerical investigation of the nominal wake in regular head waves is performed for a KVLCC2 model ship for the fully-loaded condition. Phase-averaged wake fields for one period are compared with experimental data measured using Stereo PIV, showing good agreement. The effect of the ship motion on the characteristics of the wake field and the axial velocity in the propeller plane are investigated while varying the wave length.

Experimental Investigation of the Motion Responses of a Moored Twin-Barge Model in Regular Waves in a Square Tank

  • Nguyen, Van Minh;Jeon, Myung-Jun;Yoon, Hyeon-Kyu
    • Journal of Navigation and Port Research
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    • v.42 no.2
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    • pp.127-136
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    • 2018
  • The motion response of floating structures is of significant concern in marine engineering. Floating structures can be disturbed by waves, winds, and currents that create undesirable motions of the vessel, therefore causing challenges to its operation. For a floating structure, mooring lines are provided in order to maintain its position; these should also produce a restoring force when the vessel is displaced. Therefore, it is important to investigate the tension of mooring lines and the motion responses of a twin barge when moored to guarantee the safety of the barge during its operation. It is essential to precisely identify the characteristics of the motion responses of a moored barge under different loading conditions. In this study, the motion responses of a moored twin barge were measured in regular waves of seven different wave directions. The experiment was performed with regular waves with different wavelengths and wave directions in order to estimate the twin-barge motions and the tension of the mooring line. In addition, the motion components of roll, pitch, and heave are completely free. In contrast, the surge, sway, and yaw components are fixed. In the succeeding step, a time-domain analysis is carried out in order to obtain the responses of the structure when moored. As a result, the Response Amplitude Operator (RAO) motion value was estimated for different wave directions. The results of the experiment show that the motion components of the twin barge have a significant effect on the tension of the mooring lines.

Motion of Buoyant Objects on Regular Waves (규칙파상에서 부유체의 움직임)

  • Bang, Kap-Sun;Cho, Sung-Hyun
    • The Journal of the Korea Contents Association
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    • v.7 no.4
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    • pp.170-177
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    • 2007
  • When buoyant objects appear in contents, it is helpful in developing contents to express their attributes such as their length, width, weight, and velocity, and the magnitude and direction of regular waves dynamically. Therefore, we verify how the attributes of buoyant objects and the characteristics of waves cause the heaving motion of buoyant objects to change by using the equation of motion used in the naval architecture and ocean engineering. Our research results may help contents developers to develop contents with buoyant objects even if they do not understand the naval architecture and ocean engineering well. We show that we can calculate the motion of buoyant objects dynamically even if the velocity of buoyant objects or the characteristics of waves change dynamically. In the future, we will study how buoyant objects move on the irregular waves, and develop engines for buoyant objects on the real sea.

Motion Behavior of Platform Supply Vessels Running Under Regular Wave Conditions in RANS Model

  • Park, Huiseung;Jang, Hoyun;Ahn, Namhyun;Yoon, Hyunsik
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.3
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    • pp.366-372
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    • 2019
  • This study performed a numerical analysis of a 3D unsteady viscous flow in order to investigate ship motion responses running through regular waves of the platform supply vessel. The feasibility of numerical analysis was tested under the three regular wave conditions of the KRISO container ship (KCS) suggested at the 2010 Gothenburg CFD Workshop. The resulting resistance coefficient, heave motion, and pitch angle were compared with the model test of the harmonic analysis. Also, the ship motion response characteristics of the platform supply vessel were performed using the proven method of the KRISO container ship (KCS). The ship motions including the resistance coefficient, heave motion, and pitch angle according to the time series were investigated via harmonic analysis under regular waves condition of ${\lambda}/LPP=1.87$ and $H_S=0.078m$.

Motion Analysis of a Very Large Floating Structure in Irregular Waves (불규칙파 중 초대형 부유식 해양 구조물에 대한 운동 해석)

  • 신현경;이호영;임춘규;신현수;박인규
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.04a
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    • pp.63-68
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    • 2000
  • A very large floating structure has rather small motion characteristics as to the whole body, while the motion at end part of such structure becomes largest due to the elastic motion of the structure. This paper presents on the theoretical result on the relative motion characteristics and green water phenomena of VLFS in waves This phenomena affect not only to strength of the structure but also the determination of depth of structure. To predict motion responses of structure in regular waves, the source-dipole distribution method and F.E.M is used By irregular wave results, the probability of occurrence of green water and response of the structure were calculated.

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A Stuty on the Dynamic Response of an Axisymmetric Buoy in Regular Waves (축대칭 부표의 규칙파중 운동특성에 대한 연구)

  • Key-Y.,Hong;Hyo-Chul,Kim;Hang-S.,Choi
    • Bulletin of the Society of Naval Architects of Korea
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    • v.23 no.3
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    • pp.1-9
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    • 1986
  • Herein the dynamic response of an axisymmetric buoy to regular wave is studied within linear potential theory. The buoy has a particular geometry so that it should experience minimum wave-exiting force on the vertical direction at a precribed wave number in water of finite depth. Invoking the Green's theorem a velocity potential is generated by distributing pulsating sources and doublets on the immersed surface of the buoy at its mean position. Hydrodynamic forces and moments are obtained approximately by summation of the products of linear pressure and directional mesh area over the immersed surface. Model tests are carried out to measure the wave-exciting forces, hydrodynamic forces and motion responses. The experimental results in general agree fairly well with the numerical ones. From the analytical and experimental works it is found that the pitching motion and its coupling effect affect significantly the motion characteristics of the freely-floating axisymmetric buoy in regular waves.

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Integrated CAD/CAE System for Planing Hull Form Design (활주형 선박의 선형설계를 위한 통합 CAD/CAE 시스템)

  • 김태윤;김동준
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.39 no.4
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    • pp.298-304
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    • 2003
  • In this paper a free-form hull design program and performance prediction program for planing boat is introduced. This program enables the designer to do complex geometric hull shape design on a personal computer and accurately to predict power requirements for a given loading and velocity. For a free form design, Bezier curve model is adopted as a basic representation tool of curves and surfaces, and this program has versatile functions to do fairing jobs with a convenient graphical user interface. After creating a hull form the geometric data is provided in a manner compatible with a variety of analysis tools including 'Motion Analysis(by Zarnick)' for prediction of motion characteristics in regular waves, 'Running Attitude (by Savitsky)' for prediction of the running attitude and required power.