The Prediction of Wave Groups within a Harbor to Assist Ship Operation at the Entrance

Ik-Soon Cho 한국항해항만학회 2006 한국항해항만학회지 Vol.30 No.2

Waves, which are the main source of ship motions in a seaway, considerably affect the performance of a ship. The study of waves and their impact on ship motions within harbors is an important aspect of the design and operation of harbors. The prediction of incoming groups of waves is particularly important for evaluating ship motion within a harbor. Such a prediction makes it possible to evaluate ship safety more accurately. The wave transformation model reported here is applied to actual ports based on Boussinesq wave equations both non-linear and dispersive wave processes be considered in order to capture physical effects such as wave shoaling, refractions, reflection and diffraction in variable depth environments. The prediction of incoming groups of waves is particularly important for evaluating ship motion within a harbor, Such a prediction makes it possible to evaluate ship safety more accurately and provide safe wave informations for navigation Furthermore, a wave information support system is proposed for entering ships as one technique for improving the safety of ship operations. This system predicts the run of waves and reduces the danger by identifying the most dangerous point near the harbor entrance at the small wave groups.

The Prediction of Wave Groups within a Harbor to Assist Ship Operation at the Entrance

Cho Ik-Soon Korean Institute of Navigation and Port Research 2006 한국항해항만학회지 Vol.30 No.2

Waves, which are the main source of ship motions in a seaway, considerably affect the performance of a ship. The study of waves and their impact on ship motions within harbors is an important aspect of the design and operation of harbors. The prediction of incoming groups of waves is particularly important for evaluating ship motion within a harbor. Such a prediction makes it possible to evaluate ship safety more accurately. The wave transformation model reported here is applied to actual ports based on Boussinesq wave equations both non-linear and dispersive wave processes be considered in order to capture physical effects such as wave shoaling, refractions, reflection and diffraction in variable depth environments. The prediction of incoming groups of waves is particularly important for evaluating ship motion within a harbor, Such a prediction makes it possible to evaluate ship safety more accurately and provide safe wave informations for navigation. Furthermore, a wave information support system is proposed for entering ships as one technique for improving the safety of ship operations. This system predicts the run of waves and reduces the danger by identifying the most dangerous point near the harbor entrance at the small wave groups.

컨테이너선의 조파저항 감소 기술에 대한 연구

최희종 한국항해항만학회 2024 한국항해항만학회지 Vol.48 No.4

본 논문에서는 컨테이너선의 조파 저항을 효율적으로 감소시킬 수 있는 기술과 관련하여 연구한 내용을 정리하였다. 컨테이너선에 적용이 가능한 조파저항 저감 기술을 개발하고 실선 설계에 사용하기 위하여 최적화 알고리즘, 선체 형상 변경 알고리즘, 선박 성능 예측 알고리즘, 자동화 알고리즘 그리고 반복적 최적 설계 기법을 적용하여 선형 최적 설계를 수행할 수 있는 컴퓨터 프로그램을 개발하였다. 선형 최적 설계에 있어서 중요한 요소인 설계 변수의 적절한 설정과 설계 변수의 하한과 상한을 효율적인 설정을 위하여 민감도 분석 알고리즘을 개발하여 선형 최적 설계에 적용하였다. 개발된 컴퓨터 프로그램의 신뢰성과 실선 적용성을 예측하기 위하여 전 세계적으로 다양한 연구가 진행된 컨테이너선인 KCS(KRISO Container Ship) 선박에 대한 선형 최적 설계를 수행하였다. KCS 선박의 설계 속도인 Fn=0.26에서 선형 최적 설계를 수행하였으며, 대상 선박인 KCS 선박의 선형과 선형 최적 설계의 결과로써 도출된 선박의 선형에 대한 수치해석을 수행하여 조파 저항, 파형 그리고 파고를 구하고 서로 비교하였다. 결론적으로, 최적 선박은 대상 선박과 비교하여 조파 저항이 80.60% 감소하였고, 배수량과 침수 표면적은 각각 1.54%, 1.21% 감소하는 것을 알 수 있었다. This paper aimed to summarize research on technologies that could efficiently reduce wave-making resistance of container ships. Tto develop wave resistance reduction technology that could be applied to container ships and use it in real ship design, hull-form optimal design was performed by applying optimization algorithms, hull-form change algorithms, ship performance prediction algorithms, automation algorithms, and iterative optimal design techniques. A computer program was also developed. To properly set design variables known to be important elements in hull-form optimal design and to efficiently set lower and upper limits of design variables, a sensitivity analysis algorithm was developed and applied to hull-form optimal design. To predict the reliability and applicability of the developed computer program for real ships, hull-form optimal design was performed for a KRISO Container Ship (KCS), a container ship with various studies conducted worldwide. Hull-form optimal design was performed at Fn=0.26, the design speed of the KCS ship. Numerical analysis was performed on the hull-form of the target ship, the KCS ship, and the hull-form of the ship derived as a result of the hull-form optimal design to determine wave resistance, wave system, and wave height. The optimal ship's wave resistance was found to be reduced by 80.60% compared to the target ship. The displacement and wetted surface area were also found to be reduced by 1.54% and 1.21%, respectively.

Effect of wave periods on added resistance and motions of a ship in head sea simulations

Seo, Seonguk,Park, Sunho,Koo, BonYong Elsevier 2017 Ocean engineering Vol.137 No.-

<P><B>Abstract</B></P> <P>Given that the International Maritime Organization (IMO) recently introduced the Energy Efficiency Design Index (EEDI) for new ships and the Energy Efficiency Operational Indicator (EEOI) for ship operations, accurate prediction of the added resistance of ships advancing in waves has become necessary. In the present study, the open-source computational fluid dynamics library, OpenFOAM, was used to predict the added resistance with the motions of a ship. Unstructured grid using a hanging-node and cut-cell method was used to generate fine grid around a free-surface and ship. Five wavelengths from a short wavelength (<I>λ/L</I> <SUB> <I>PP</I> </SUB>=0.65) to a long wavelength (<I>λ/L</I> <SUB> <I>PP</I> </SUB>=1.95) were considered as head waves. The grid uncertainty was evaluated with respect to three grid systems for a wavelength of <I>λ/L</I> <SUB> <I>PP</I> </SUB>=1.15. The predicted added resistance and heave and pitch motions with various head waves were compared with the data from model experiments. The wave pattern around the ship and the motions of the ship were analyzed with respect to the wave encounter period. When the wavelength was similar to the ship length, the ship moved against the waves, and thus the added resistance was greater compared with other wavelengths.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Added resistance is small in waves with short and long wavelengths. </LI> <LI> When wavelength is similar to ship length, ship moves against waves. </LI> <LI> Long wavelength makes to easier prediction of added resistance. </LI> <LI> Vortices structures around stern by ship motions are presented. </LI> </UL> </P>

비선형분산파랑모형을 이용한 항주파의 발생과 전파에 관한 수치예측모형 개발

신승호(Seung-Ho Shin),정대득(Dae-Deug Jeong) 한국항해항만학회 2003 한국항해항만학회지 Vol.27 No.5

선박의 항행에 의해 발생되는 항주파의 특성은 선박의 속도와 수심 조건에 따라 크게 달라진다. 연안 항로에서 발생된 항주파는 주변 해안으로 전파됨에 따라 항만 내의 정온 수역을 교란하여 정박 중인 소형선박, 수영객 등에 돌발적이고도 심각한 위험을 가져다 줄뿐만 아니라 해안의 침식, 호안의 결과 등의 피해를 주기도 한다. 지금까지 항주파에 관한 연구의 관심사는 일정 수심 조건에 대해 조파저항이나 조선에 미치는 영향을 분석하는 등 주로 조선공학도의 관점에서 검토가 대상이 되어 왔으며, 가변 수심을 가진 실제 해역에 있어서의 항주파 발생과 전파에 기인한 주변 해역의 영향은 그다지 검토되지 못하였다. 최근 고속선 등의 발달로 인해 천해역에서의 항주파로 인한 인근 해역의 피해가 더욱 우려되고 있는 추세이다. 따라서 실제 수역에서의 항주파의 발달과 그 전파과정은 조사할 필요가 있는 것이다. 본 연구에서는 연안 해역의 얕고 복잡한 수로와 다양한 선속 조건에 대한 항주파의 발생 및 전파를 예측하기 위하여 고정 좌표계에서 Boussinesq 방정식을 토대로 항주파 수치예측 모형을 구축하였다. 제안된 모형은 수리모형실험 결과와의 비교를 통하여 검증하였으며, 또한 실제 수로를 토대로 한 가변 수심역에 개발된 모형을 적용하여 수심 변화 고려의 중요성을 확인하였다. The characteristics of ship induced waves caused by navigation become widely different from both ship’s speed and water depth condition. The ship induced waves specially generated in coastwise routes frequently give rise to call unforeseen danger for swimmers and small boats as well as shoreline erosion or sea wall destruction in coastal, zones. The main, concern of ship induced wave study until now is either how to reduce ship resistance or how to manoeuvre the shin safely under a constant water depth in the view point of shipbuilding engineers. Moreover, due to the trends for appearance of the high speed ships at the shallow coastal water, we are confronted with the danger of damages from those ship induced waves. Therefore, it is necessary to examine the development of ship induced waves and the influence of their deformation effects according to its propagation ray. In present study, in order to predict the development of the ship induced waves and their propagation under the conditions of complicate and variable shallow water depth with varying ship’s speed, we constructed a computer model using Boussinesq equation with a fixed coordinate system and verified the model results by comparison with experimental results. Additionally, the model was applied under the variable water depth based on actual passage and we then confirmed the importance of the variable water depth consideration.

Three-dimensional study on the interaction between a container ship and freak waves in beam sea

Wang Jiaqian,Qin Hao,Hu Zhe,Mu Lin 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-

Freak wave occurs unexpectedly in the ocean with an extreme wave crest and focused wave energy, resulting in many marine accidents. The interaction between a container ship and freak waves in beam sea is studied in this paper to better understand the influence of freak waves on ships. A threedimensional in-house solver is developed and validated for the freak wave generation and the waveship interaction. Characteristics of the interaction process, motion responses of the ship and the green water loadings induced by the freak waves are obtained and analyzed. Comparisons are carried out to reveal the influences of the freak wave crest and sequence on the roll, heave and impact pressures. Relations between motion responses of the ship and the green water event are discussed. Influences of ship speeds on the wave-ship interaction are addressed.

비선형분산파랑모형을 이용한 항주파의 발생과 전파에 관한 수치예측모형 개발

신승호(Seung-Ho Shin),정대득(Dae-Deug Jeong) 한국항해항만학회 2003 한국항해항만학회 학술대회논문집 Vol.3 No.-

선박의 항행에 의해 발생되는 항주파의 특성은 선박의 속도와 수심 조건에 따라 크게 달라지며, 연안 항로에서 발생된 항주파는 주변해안으로 전파됨에 따라 항만 내의 정온 수역을 교란하여 정박 중인 소형선박, 수영객 등에 돌발적이고도 심각한 위험을 가져다 줄뿐만 아니라 해안의 침식, 호안의 결과 등의 피해를 주기도 한다. 지금까지 항주파에 관한 연구는 일정 수심 조건에 대해 조파저항이나 조선에 미치는 영향을 분석하는 등 주로 조선공학적인 측면에서의 검토가 대상이 되어 왔으며, 가변 수심을 가진 실제 해역에 있어서의 항주파 발생과 전파에 기인한 주변해역의 영향은 그다지 검토되지 못하였다. 최근 고속선 등의 발달로 인해 천해역에서의 항주파로 인한 인근 해역의 피해가 더욱 우려되고 있는 추세이며 그에 따라 실제 수역에서의 항주파와 그의 전파를 예측할 수 있는 모형의 개발이 절실히 요구된다고 할 수 있다. 본 연구에서는 연안 해역의 얕고 복잡한 수로와 다양한 선속 조건에 대한 항주파의 발생 및 전파를 예측하기 위하여 고정 좌표계에서 비선형분산피동모형을 토대로 항주파 수치예측 모형을 구축하였다. 제안된 모형은 수리모형실험 결과와의 비교를 통하여 검증하였으며, 추가로 실제 수로를 토대로 가변 수심역에서의 항주파를 모의함으로서 모형의 적용성 및 수심 변화 고려의 중요성을 확인하였다. In the past, the main concern of ship induced waves was either how to reduce ship resistance or how to keep ship handling under the constant depth condition in the view point of shipbuilding. However, the characteristics of ship induced waves caused by navigation become widely different from both ship's speed and depth condition, the ship induced waves then specially generated in coastwise routes frequently give rise to unforeseen danger for swimmers, sea walls and small boats as well as shoreline erosion in coastal zone. Therefore it was required further examination for influence of the wave deformation effects according to its propagation. In present study, in order to predict the ship induced wave propagation under the complicate and variable shallow water condition, we constructed the model using Boussinesq equation and verified by comparison with experimental results. Additionally, the model was applied under the variable depth based on actual passage and we then confirmed the importance of the variable depth consideration.

Experimental Investigation of the Hydrodynamic Force Acting on Ship Hull and Rudder in Various Wave Direction

Nguyen, Van Minh,Nguyen, Tien Thua,Seo, Juwon,Yoon, Hyeon Kyu,Kim, Yeon Gyu Korean Society of Ocean Engineers 2018 Journal of advanced research in ocean engineering Vol.4 No.3

In the past, traditional methods of research on ship maneuvering performance were estimated in calm waters. However, the course-keeping ability and the maneuvering performance of a ship can be influenced by the presence of waves. Therefore, it is necessary to understand the maneuvering behavior of a ship in waves. In this study, the force acting on a moving ship and a rudder behind the model ship will be performed in regular waves in Changwon National University (CWNU). In addition, the prediction force acting on the rudder in calm waters was carried out and compared with those of Computational Fluid Dynamics (CFD). Model test in regular wave was performed to predict the force acting on the ship and the rudder behind the model ship in various wave directions. The effects of wavelength and wave direction on hydrodynamic forces acting on the ship hull versus rudder angle is discussed.

안전성 및 효율성 관점에서의 다목적 실선 실험

이상원,Kenji Sasa,조익순 한국항해항만학회 2023 한국항해항만학회 학술대회논문집 Vol.2023 No.2

In recent years, the need for economical and sustainable ship routing has emerged due to the enforced regulations on environmental issues. Despite the development of weather forecasting technology, maritime accidents by rough waves have continued to occur due to incorrect weather forecasts. In this study, onboard measurements are conducted to observe the acutal situation on merchant ships in operation encountering rough waves. The types of measured data include information related to navigation (Ship’s position, speed, bearing, rudder angle) and engine (engine revolutions, power, shaft thrust, fuel consumption), weather conditions (wind, waves), and ship motions (roll, pitch, and yaw). These ship experiments was conducted to 28,000 DWT bulk carrier, 63,000 DWT bulk carrier, 20,000 TEU container ship, and 12,000 TEU container ship. The actual ship experiment of each ship is intended to acquire various types of data and utilize them for multi-objective studies related to ship operation. Additionally, in order to confirm the sea conditions, the directional wave spectrum was reproduced using a wave simulation model. Through data collection from ship experiments and wave simulations, various studies could be proceeding such as the measurement for accurate wave information by marine radar and analysis for cargo collapse accidents. In addition, it is expected to be utilized in various themes from the perspective of safety and efficiency in ship operation. 최근 환경오염에 대한 규제 강화로 인해 선박 운항은 경제적이며 지속가능한 최적화 항법에 대한 필요성이 대두되고 있다. 하지만 기상예보 기술의 발전에도 불구하고, 여전히 잘못된 기상예보로 인한 악천후에 조우하는 선박 사고들은 지속적으로 발생하고 있다. 본 연구 에서는 악천후에 조우하는 선박의 실태를 파악하고 분석하기 위해, 운항중인 선박의 정보를 측정하고자 하였다. 여기서 측정한 데이터의 종 류는 항해 (위치, 속도, 방위, 타각 등) 및 엔진 (엔진 회전수, 출력, 축 추력, 연료 소비량) 관련 정보, 기상 상태 (바람, 파도), 선박운동 (선박 종, 횡운동 등) 등의 정보들이 포함되었다. 실측 실험을 시행한 선박의 종류는 28,000 DWT급 벌크선, 63,000 DWT급 벌크선, 20,000 TEU급 컨테이너선, 12,000 TEU급 컨테이너선박이다. 각 선박의 실선실험은 여러 가지 종류의 데이터를 각각 취득하여 다목적으로 선박 운항에 관 련한 연구들에 활용하고자 한다. 또한 실선실험 시의 해상 상태를 확인하기 위해, 파도 시뮬레이션 모델을 이용하여 방향성 파랑 스펙트럼 등 을 재현하였다. 실선 실험의 데이터 취득 및 파도 시뮬레이션 결과 등을 통하여, 선박레이더를 이용한 정확한 파도정보 파악 및 화물 붕괴 사 고 등에 대한 연구를 진행하고 있다. 이에 더불어, 선박운항의 안전성 및 효율성 관점에서 다양하게 활용될 것으로 기대된다.

선박 운항 시뮬레이터에서 해양파와 연동된 선박 및 부표 운동의 실시간 가시화

여동진(Dong Jin Yeo),차무현(Moohyun Cha),문두환(Duhwan Mun) (사)한국CDE학회 2011 한국CDE학회 논문집 Vol.16 No.3

Ship handling simulator should have capabilities of calculating ship motions (heave, pitch, and roll) at given sea state and displaying the calculated motions through a real-time 3D visualization system. Motion solver of a ship handling simulator generally calculates those motions in addition to position for an own ship, a main simulation target, but provides only position information for traffic ships. Therefore, it is required to simulate real-time traffic ship and buoy motions coupled with ocean waves in a ship handling simulator for the realistic visualization. In the paper, the authors propose a simple dynamics model by which ship and buoy motions are calculated with the input data of wave height and discuss a method for the implementation of a ship and buoy motions calculation module.