Pub Date : 2024-11-08DOI: 10.1016/j.oceaneng.2024.119421
Fang Li , Shengliang Lin , Heping Li , Jianchuan Yin , Dexin Li , Jinshui Zhang
Inland shipping of the Pearl River plays an important role in the Chinese shipping system. To ensure navigation safety, we collect reports of maritime accidents from 2015 to 2022 in the Pearl River basin. This article extracts influencing factors by collecting the experience of inland waterway safety navigation and analyzing accident reports. Then, this paper uses the interpretative structural modeling method (ISM) to build a correlation model. Using a data-driven Bayesian network (BN), it analyzes the impact of various factors on the safety navigation in the Pearl River. The model validation is completed by compared with tree augmented naive Bayes classifiers (TAN) network using the same validation samples, through validation with the test set, the prediction accuracy has improved by 25%. The results indicate factors such as vessel type, accident month, accident day and time, etc. have a significant impact on the safety of navigation in the inland Pearl River waterway. The method used can identify important risk factors for accidents and the average predictive probability of validation samples reaches 87.03%. These research results could be extended to maritime management efforts in the Pearl River Basin.
{"title":"A data-driven ISM-BN model for safety analysis of inland shipping in the Pearl River Basin","authors":"Fang Li , Shengliang Lin , Heping Li , Jianchuan Yin , Dexin Li , Jinshui Zhang","doi":"10.1016/j.oceaneng.2024.119421","DOIUrl":"10.1016/j.oceaneng.2024.119421","url":null,"abstract":"<div><div>Inland shipping of the Pearl River plays an important role in the Chinese shipping system. To ensure navigation safety, we collect reports of maritime accidents from 2015 to 2022 in the Pearl River basin. This article extracts influencing factors by collecting the experience of inland waterway safety navigation and analyzing accident reports. Then, this paper uses the interpretative structural modeling method (ISM) to build a correlation model. Using a data-driven Bayesian network (BN), it analyzes the impact of various factors on the safety navigation in the Pearl River. The model validation is completed by compared with tree augmented naive Bayes classifiers (TAN) network using the same validation samples, through validation with the test set, the prediction accuracy has improved by 25%. The results indicate factors such as vessel type, accident month, accident day and time, etc. have a significant impact on the safety of navigation in the inland Pearl River waterway. The method used can identify important risk factors for accidents and the average predictive probability of validation samples reaches 87.03%. These research results could be extended to maritime management efforts in the Pearl River Basin.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119421"},"PeriodicalIF":4.6,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.oceaneng.2024.119720
Chao Feng , Lingrong Kong , Yu Wang , Kunkun Li , Yulin Gao
Accurate pulsed and continuous waterjet process modeling is crucial for enhancing vertical jet efficiency in marine structure installation and dredging projects. In this paper, the numerical model of the scouring process is established using the smoothed particle hydrodynamics (SPH). Firstly, the experimental data of pulsed jet scouring the cohesive bed confirms the model's accuracy. In addition, a comparative analysis between pulsed and continuous waterjet scouring mechanisms is conducted, along with an investigation into factors influencing scour hole size and efficiency. The results show that the shape of the scour hole obtained by simulation and experiment is gourd-shaped, and the average error of the scour hole depth is 4.1 %, which verifies the accuracy of the numerical model. The scouring mechanism can be regarded as vertical crack generation, development, and disappearance, transitioning from shear failure to erosion dominance. Furthermore, the jet angle has a significant impact on both the scour hole size and the efficiency ratio. At an optimal injection angle of 30°, the efficiency ratio can reach up to 124.4%. This study addresses the gap in comparative analysis between pulsed and continuous waterjet scouring mechanisms and holds promising applications in engineering, including dredging and anchor extraction from sediments.
{"title":"Numerical simulation of cohesive bed impinging by submerged pulsed and continuous waterjet based on SPH algorithm","authors":"Chao Feng , Lingrong Kong , Yu Wang , Kunkun Li , Yulin Gao","doi":"10.1016/j.oceaneng.2024.119720","DOIUrl":"10.1016/j.oceaneng.2024.119720","url":null,"abstract":"<div><div>Accurate pulsed and continuous waterjet process modeling is crucial for enhancing vertical jet efficiency in marine structure installation and dredging projects. In this paper, the numerical model of the scouring process is established using the smoothed particle hydrodynamics (SPH). Firstly, the experimental data of pulsed jet scouring the cohesive bed confirms the model's accuracy. In addition, a comparative analysis between pulsed and continuous waterjet scouring mechanisms is conducted, along with an investigation into factors influencing scour hole size and efficiency. The results show that the shape of the scour hole obtained by simulation and experiment is gourd-shaped, and the average error of the scour hole depth is 4.1 %, which verifies the accuracy of the numerical model. The scouring mechanism can be regarded as vertical crack generation, development, and disappearance, transitioning from shear failure to erosion dominance. Furthermore, the jet angle has a significant impact on both the scour hole size and the efficiency ratio. At an optimal injection angle of 30°, the efficiency ratio can reach up to 124.4%. This study addresses the gap in comparative analysis between pulsed and continuous waterjet scouring mechanisms and holds promising applications in engineering, including dredging and anchor extraction from sediments.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119720"},"PeriodicalIF":4.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.oceaneng.2024.119690
Junhoi Choi , Yonghwan Kim , Zhang Zhu , Shuguang Wang
This study conducted a numerical planar motion mechanism (PMM) test for a containership, considering the effects of finite depth. An OpenFOAM-based computational fluid dynamics (CFD) approach was employed to conduct the simulations. Before conducting a series of numerical computations, uncertainty analysis for the grid size and time step was performed to ensure the reliability of the computational results. Two PMM tests, static drift and pure yaw, were conducted, and the results were validated against experimental data. The comparison demonstrated good agreement between forces, moments, and hydrodynamic coefficients when compared with both experimental and other computational results. Furthermore, a comparison between a first- and second-order combination model and a first- and third-order combination model revealed that the latter showed better alignment with experimental data in deep water, while the former performed better in shallow water, emphasizing the role of crossflow. This study contributes to understanding the differences in maneuvering performance between deep and shallow water conditions.
{"title":"Numerical PMM test in finite depth","authors":"Junhoi Choi , Yonghwan Kim , Zhang Zhu , Shuguang Wang","doi":"10.1016/j.oceaneng.2024.119690","DOIUrl":"10.1016/j.oceaneng.2024.119690","url":null,"abstract":"<div><div>This study conducted a numerical planar motion mechanism (PMM) test for a containership, considering the effects of finite depth. An OpenFOAM-based computational fluid dynamics (CFD) approach was employed to conduct the simulations. Before conducting a series of numerical computations, uncertainty analysis for the grid size and time step was performed to ensure the reliability of the computational results. Two PMM tests, static drift and pure yaw, were conducted, and the results were validated against experimental data. The comparison demonstrated good agreement between forces, moments, and hydrodynamic coefficients when compared with both experimental and other computational results. Furthermore, a comparison between a first- and second-order combination model and a first- and third-order combination model revealed that the latter showed better alignment with experimental data in deep water, while the former performed better in shallow water, emphasizing the role of crossflow. This study contributes to understanding the differences in maneuvering performance between deep and shallow water conditions.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119690"},"PeriodicalIF":4.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.oceaneng.2024.119723
Shizhuang Chen , Weiya Xu , Yelin Feng , Long Yan , Huanling Wang , Wei-Chau Xie
Landslide-generated impulse waves are characterized by their sudden and catastrophic nature, often limiting the availability of actual measurement data. To address this challenge, physical model experiments effectively replicate such geological hazards. Based on the Meilishi landslide in the Gushui Reservoir, a 1:150 scale three-dimensional prototype physical model is constructed, with sliding velocity as an independent variable to carry out 10 scenarios. Results reveal that the generated waves in the near field are nonlinear transitional waves, characterized by fragmentation and fluctuation. Unlike submarine and partially-submerged landslides, subaerial landslides generate larger wave crests first and then troughs. The maximum primary wave amplitude is positively correlated with the Froude number, as the larger the Froude number results in stronger impacts and higher wave generation efficiency. Wave propagation can be divided into rapid and gentle attenuation, with higher sliding velocities leading to faster attenuation along the river. A formula for calculating the maximum wave run-up on the dam is derived, showing good agreement between predicted and experimental values. This study's findings help us further understand the whole generation and propagation process of impulse waves induced by the potential failure of the Meilishi landslide, and the results contribute to studies of similar tsunami hazards worldwide.
{"title":"Experimental investigation on potential high-position landslide-generated impulse waves: A case study of the Meilishi landslide in the Gushui Reservoir, China","authors":"Shizhuang Chen , Weiya Xu , Yelin Feng , Long Yan , Huanling Wang , Wei-Chau Xie","doi":"10.1016/j.oceaneng.2024.119723","DOIUrl":"10.1016/j.oceaneng.2024.119723","url":null,"abstract":"<div><div>Landslide-generated impulse waves are characterized by their sudden and catastrophic nature, often limiting the availability of actual measurement data. To address this challenge, physical model experiments effectively replicate such geological hazards. Based on the Meilishi landslide in the Gushui Reservoir, a 1:150 scale three-dimensional prototype physical model is constructed, with sliding velocity as an independent variable to carry out 10 scenarios. Results reveal that the generated waves in the near field are nonlinear transitional waves, characterized by fragmentation and fluctuation. Unlike submarine and partially-submerged landslides, subaerial landslides generate larger wave crests first and then troughs. The maximum primary wave amplitude is positively correlated with the Froude number, as the larger the Froude number results in stronger impacts and higher wave generation efficiency. Wave propagation can be divided into rapid and gentle attenuation, with higher sliding velocities leading to faster attenuation along the river. A formula for calculating the maximum wave run-up on the dam is derived, showing good agreement between predicted and experimental values. This study's findings help us further understand the whole generation and propagation process of impulse waves induced by the potential failure of the Meilishi landslide, and the results contribute to studies of similar tsunami hazards worldwide.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119723"},"PeriodicalIF":4.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An emergency fire pump is a critical equipment which assists the ship crew in handling extreme emergency situations involving fire on-board tanker ships. In case the main fire pump becomes ineffective during a fire, the emergency fire pump is used to extinguish the fire. In this case, it is necessary for the ship's crew to operate and use the pump without any failure. The aim of this study is to systematically predict human (crew) reliability for emergency fire pump operational processes on tanker ships since human dependability plays a significant role in safer shipment. To achieve this goal, fuzzy and BN (Bayesian Network) CREAM (Cognitive Reliability and Error Analysis Method) modelling is applied. CREAM is used to methodically estimate the probability of human error within a fuzzy set that accounts for uncertainties of CPC (Common Performance Condition), while BN is competent in estimating control modes in CREAM's reliability analysis. The paper's findings show ship crew reliability (9.08E-01) for the emergency fire pump operation process on tanker ships. These findings are expected to provide valuable information to prevent human errors and improve safety on tanker ships during firefighting, thereby reassuring the maritime industry of the potential for increased safety.
{"title":"Predicting human reliability for emergency fire pump operational process on tanker ships utilising fuzzy Bayesian Network CREAM modelling","authors":"Muhammet Aydin , Sukru Ilke Sezer , Seher Suendam Arici , Emre Akyuz","doi":"10.1016/j.oceaneng.2024.119717","DOIUrl":"10.1016/j.oceaneng.2024.119717","url":null,"abstract":"<div><div>An emergency fire pump is a critical equipment which assists the ship crew in handling extreme emergency situations involving fire on-board tanker ships. In case the main fire pump becomes ineffective during a fire, the emergency fire pump is used to extinguish the fire. In this case, it is necessary for the ship's crew to operate and use the pump without any failure. The aim of this study is to systematically predict human (crew) reliability for emergency fire pump operational processes on tanker ships since human dependability plays a significant role in safer shipment. To achieve this goal, fuzzy and BN (Bayesian Network) CREAM (Cognitive Reliability and Error Analysis Method) modelling is applied. CREAM is used to methodically estimate the probability of human error within a fuzzy set that accounts for uncertainties of CPC (Common Performance Condition), while BN is competent in estimating control modes in CREAM's reliability analysis. The paper's findings show ship crew reliability (9.08E-01) for the emergency fire pump operation process on tanker ships. These findings are expected to provide valuable information to prevent human errors and improve safety on tanker ships during firefighting, thereby reassuring the maritime industry of the potential for increased safety.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119717"},"PeriodicalIF":4.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.oceaneng.2024.119721
Kejie Zhai , Ian D. Moore
Cured-in-place-pipe (CIPP) liners have been widely used in rehabilitation of gravity flow pipelines. However, the host pipe rehabilitated by the CIPP liner may be subject to shear force and shear displacement at the joint. In this study, a finite element model of a rigid host pipe with liner under shear action is established and used to study the resulting behaviour. Controlling factors such as the gap spanned by the liner between host pipes across the joint, diameter, the liner thickness, the elastic modulus of the liner, and the coefficient of friction between host pipe and liner are studied. The liner stress, displacement, and shear force are reported. Shear stiffness and stress equations are then fitted based on 286 data points. The results show that the maximum stress on the inner surface of the liner occurs at the shoulder and haunch, and the maximum stress on the outer surface occurs at the springline. The inner surface stresses at the crown and invert decrease with increases in liner-host pipe friction, but increase at the shoulder and haunch. Coefficient of Friction has almost no effect on the stresses that develop on the outside surface of the liner.
{"title":"Mechanical study and equations for gravity flow pipe liners stretching across ring fractures or joints under shear action","authors":"Kejie Zhai , Ian D. Moore","doi":"10.1016/j.oceaneng.2024.119721","DOIUrl":"10.1016/j.oceaneng.2024.119721","url":null,"abstract":"<div><div>Cured-in-place-pipe (CIPP) liners have been widely used in rehabilitation of gravity flow pipelines. However, the host pipe rehabilitated by the CIPP liner may be subject to shear force and shear displacement at the joint. In this study, a finite element model of a rigid host pipe with liner under shear action is established and used to study the resulting behaviour. Controlling factors such as the gap spanned by the liner between host pipes across the joint, diameter, the liner thickness, the elastic modulus of the liner, and the coefficient of friction between host pipe and liner are studied. The liner stress, displacement, and shear force are reported. Shear stiffness and stress equations are then fitted based on 286 data points. The results show that the maximum stress on the inner surface of the liner occurs at the shoulder and haunch, and the maximum stress on the outer surface occurs at the springline. The inner surface stresses at the crown and invert decrease with increases in liner-host pipe friction, but increase at the shoulder and haunch. Coefficient of Friction has almost no effect on the stresses that develop on the outside surface of the liner.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119721"},"PeriodicalIF":4.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.oceaneng.2024.119650
Ben Zhang , Yinglong Zhao , Jingyue You , Zhen Zhang
Due to their function in damping and attenuating vibrations, as well as their relatively low cost, rubber isolators have widespread applications in industries such as aerospace, automotive and maritime. As components with distinct nonlinear behavior, accurately predicting the dynamic characteristics of isolators is essential for overall structural design and vibration noise prediction. Although extensive research has been conducted on the static and dynamic performance of rubber isolators, there has been limited investigation into performance under certain specialized application scenarios, such as hydrostatic pressure environments. These environments are indeed real, for instance, isolators employed in the bow ballast tank of underwater vehicle to mitigate vibrations during weapon launch processes. In such instances, isolators are subjected not only to the influence of added mass due to the water medium during vibration but also to increasing hydrostatic pressure on the isolator surface with increasing depth. This study introduces an original experimental apparatus capable of measuring the dynamic stiffness of isolators while simulating hydrostatic pressure conditions. The constitutive model parameters governing the hyperelastic and viscoelastic properties of rubber were identified via nonlinear tests, serving as input parameters for numerically predicting the dynamic stiffness within a water medium environment. Furthermore, a comprehensive analysis was conducted to evaluate the impacts of preload, water medium, boundary conditions, and hydrostatic pressure on the dynamic stiffness of the isolator. Results indicate that preload tends to reduce peak dynamic stiffness in the shear directions, while the water medium significantly increases high-frequency dynamic stiffness in the shear directions. Within the range of 1 MPa, the impact of increasing hydrostatic pressure on dynamic stiffness can be largely disregarded. When calculating the dynamic stiffness of the isolator, it is crucial to consider the actual installation environment and set the acoustic boundary conditions of the surrounding water domain accordingly.
{"title":"Experimental and numerical analysis of rubber isolator dynamic stiffness under hydrostatic pressure","authors":"Ben Zhang , Yinglong Zhao , Jingyue You , Zhen Zhang","doi":"10.1016/j.oceaneng.2024.119650","DOIUrl":"10.1016/j.oceaneng.2024.119650","url":null,"abstract":"<div><div>Due to their function in damping and attenuating vibrations, as well as their relatively low cost, rubber isolators have widespread applications in industries such as aerospace, automotive and maritime. As components with distinct nonlinear behavior, accurately predicting the dynamic characteristics of isolators is essential for overall structural design and vibration noise prediction. Although extensive research has been conducted on the static and dynamic performance of rubber isolators, there has been limited investigation into performance under certain specialized application scenarios, such as hydrostatic pressure environments. These environments are indeed real, for instance, isolators employed in the bow ballast tank of underwater vehicle to mitigate vibrations during weapon launch processes. In such instances, isolators are subjected not only to the influence of added mass due to the water medium during vibration but also to increasing hydrostatic pressure on the isolator surface with increasing depth. This study introduces an original experimental apparatus capable of measuring the dynamic stiffness of isolators while simulating hydrostatic pressure conditions. The constitutive model parameters governing the hyperelastic and viscoelastic properties of rubber were identified via nonlinear tests, serving as input parameters for numerically predicting the dynamic stiffness within a water medium environment. Furthermore, a comprehensive analysis was conducted to evaluate the impacts of preload, water medium, boundary conditions, and hydrostatic pressure on the dynamic stiffness of the isolator. Results indicate that preload tends to reduce peak dynamic stiffness in the shear directions, while the water medium significantly increases high-frequency dynamic stiffness in the shear directions. Within the range of 1 MPa, the impact of increasing hydrostatic pressure on dynamic stiffness can be largely disregarded. When calculating the dynamic stiffness of the isolator, it is crucial to consider the actual installation environment and set the acoustic boundary conditions of the surrounding water domain accordingly.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119650"},"PeriodicalIF":4.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel partitioned function decomposition method is proposed and validated for accurately and effectively solving the interaction between waves and ships with sloshing effect. This scheme employs a hybrid functional-decomposition method that utilizes both potential and viscous flows to accurately and efficiently solve the wave-ship interaction in the external domain, while employing the original viscous method for simulating sloshing in the internal domain. To further enhance computational efficiency, a single-phase Level-set method is employed. Firstly, the issue of non-conservation in the level-set model is addressed through the application of a mass correction method. Additionally, based on the principle of mass conservation, modifications are made to the boundary conditions for free surface motion. As a result, an improved single-phase Level-set method is developed, which combines jump condition correction and mass correction. Through simulations involving linear and nonlinear free surfaces, impulsive pressures, overall forces on the tank, as well as comparisons with experimental data, it is observed that the proposed Level-set method effectively solves the sloshing in the internal domain, a problem for which the traditional single-phase Level-set method often fails to tackle with. Subsequently, by adopting a multi-block grid technique to mark tank and non-tank grid blocks and integrating the improved single-phase Level-set method with the SWENSE model, a partitioned function decomposition method is established to handle ship motions with sloshing effect in waves. It is found that simultaneously solving the internal and external flow problems using traditional implicit and explicit motion-solving methods poses certain challenges. Therefore, an implicit-inner-iteration solution method is proposed. By combining the proposed motion-solving method with the partitioned function decomposition model, satisfactory results are achieved for the wave-ship-sloshing interaction.
{"title":"A partitioned functional-decomposition scheme for modelling wave-ship-sloshing interaction","authors":"Jiawei Yu , Chaobang Yao , Guohua Dong , Fanchen Zhang , Zhiguo Zhang , Dakui Feng","doi":"10.1016/j.oceaneng.2024.119715","DOIUrl":"10.1016/j.oceaneng.2024.119715","url":null,"abstract":"<div><div>A novel partitioned function decomposition method is proposed and validated for accurately and effectively solving the interaction between waves and ships with sloshing effect. This scheme employs a hybrid functional-decomposition method that utilizes both potential and viscous flows to accurately and efficiently solve the wave-ship interaction in the external domain, while employing the original viscous method for simulating sloshing in the internal domain. To further enhance computational efficiency, a single-phase Level-set method is employed. Firstly, the issue of non-conservation in the level-set model is addressed through the application of a mass correction method. Additionally, based on the principle of mass conservation, modifications are made to the boundary conditions for free surface motion. As a result, an improved single-phase Level-set method is developed, which combines jump condition correction and mass correction. Through simulations involving linear and nonlinear free surfaces, impulsive pressures, overall forces on the tank, as well as comparisons with experimental data, it is observed that the proposed Level-set method effectively solves the sloshing in the internal domain, a problem for which the traditional single-phase Level-set method often fails to tackle with. Subsequently, by adopting a multi-block grid technique to mark tank and non-tank grid blocks and integrating the improved single-phase Level-set method with the SWENSE model, a partitioned function decomposition method is established to handle ship motions with sloshing effect in waves. It is found that simultaneously solving the internal and external flow problems using traditional implicit and explicit motion-solving methods poses certain challenges. Therefore, an implicit-inner-iteration solution method is proposed. By combining the proposed motion-solving method with the partitioned function decomposition model, satisfactory results are achieved for the wave-ship-sloshing interaction.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119715"},"PeriodicalIF":4.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-06DOI: 10.1016/j.oceaneng.2024.119519
Longhuan Zhu , Md. Mamun R. Patwary , Richards C. Sunny , Igor Tsukrov , Michael Chambers , David W. Fredriksson
With the expansion of macroalgae aquaculture in oceanic waters, especially of order Laminariales, a need exists to have optimized cultivation systems suitable for exposed conditions. To enable the design of such systems with a quantifiable level of confidence, in this paper, we developed a high-fidelity hydrodynamic modeling technique for kelp farms by introducing equivalent kelp elements for kelp aggregates with Reynolds number-based drag coefficients. After validating the model with towing tests for model kelp aggregates, it was then compared with comprehensive field datasets for a single line cultivation system with two mooring connections, in Saco Bay, Maine. The model yielded a larger tension than the measured tension by 23.3% on the west mooring line but a smaller tension by 23.2% on the east mooring line. The discrepancies may be caused by the uncertainties in the model configuration and input due to difficulties quantifying exact longline orientation, anchor-anchor distance, current reduction along the kelp longline, kelp mass density, and rope axial stiffness. Sensitivity analysis indicates that addressing these uncertainties may improve the model technique. Even though, the developed model is still reliable with a safety factor in the application for the design, installation and management of kelp aquaculture farms.
{"title":"Hydrodynamic modeling of kelp (Saccharina latissima) farms: From an aggregate of kelp to a single line cultivation system","authors":"Longhuan Zhu , Md. Mamun R. Patwary , Richards C. Sunny , Igor Tsukrov , Michael Chambers , David W. Fredriksson","doi":"10.1016/j.oceaneng.2024.119519","DOIUrl":"10.1016/j.oceaneng.2024.119519","url":null,"abstract":"<div><div>With the expansion of macroalgae aquaculture in oceanic waters, especially of order <em>Laminariales</em>, a need exists to have optimized cultivation systems suitable for exposed conditions. To enable the design of such systems with a quantifiable level of confidence, in this paper, we developed a high-fidelity hydrodynamic modeling technique for kelp farms by introducing equivalent kelp elements for kelp aggregates with Reynolds number-based drag coefficients. After validating the model with towing tests for model kelp aggregates, it was then compared with comprehensive field datasets for a single line cultivation system with two mooring connections, in Saco Bay, Maine. The model yielded a larger tension than the measured tension by 23.3% on the west mooring line but a smaller tension by 23.2% on the east mooring line. The discrepancies may be caused by the uncertainties in the model configuration and input due to difficulties quantifying exact longline orientation, anchor-anchor distance, current reduction along the kelp longline, kelp mass density, and rope axial stiffness. Sensitivity analysis indicates that addressing these uncertainties may improve the model technique. Even though, the developed model is still reliable with a safety factor in the application for the design, installation and management of kelp aquaculture farms.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119519"},"PeriodicalIF":4.6,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-06DOI: 10.1016/j.oceaneng.2024.119582
Chenguang Liu , Tailong Li , Wenxiang Wu , Huarong Zheng , Jiacheng Li , Xiumin Chu
To improve the energy efficiency and path following performance of autonomous ships, this paper proposes a Maneuvering Modeling Group (MMG) model based Event-Triggered Model Predictive Control (MET-MPC) method. Firstly, the path following control is transformed into a ship course control problem with the improved Line of Sight (LOS) guidance law considering drift angle, and an MMG model is applied to deal with variable sailing speeds. Then, a hyperbolic tangent function is introduced as the triggering threshold to reduce computational burden and energy consumption. Specifically, a dynamic buffer is introduced to store the optimal control sequence computed during each event triggering, which can keep the previous control input with no event triggered. Simulation experiments show that, the proposed MET-MPC method has better energy-saving performance and can reduce the steering frequency by up to 38.1% compared to the method without using the event-triggered mechanism.
{"title":"Event-triggered predictive path following control of autonomous ships with an MMG model","authors":"Chenguang Liu , Tailong Li , Wenxiang Wu , Huarong Zheng , Jiacheng Li , Xiumin Chu","doi":"10.1016/j.oceaneng.2024.119582","DOIUrl":"10.1016/j.oceaneng.2024.119582","url":null,"abstract":"<div><div>To improve the energy efficiency and path following performance of autonomous ships, this paper proposes a Maneuvering Modeling Group (MMG) model based Event-Triggered Model Predictive Control (MET-MPC) method. Firstly, the path following control is transformed into a ship course control problem with the improved Line of Sight (LOS) guidance law considering drift angle, and an MMG model is applied to deal with variable sailing speeds. Then, a hyperbolic tangent function is introduced as the triggering threshold to reduce computational burden and energy consumption. Specifically, a dynamic buffer is introduced to store the optimal control sequence computed during each event triggering, which can keep the previous control input with no event triggered. Simulation experiments show that, the proposed MET-MPC method has better energy-saving performance and can reduce the steering frequency by up to 38.1% compared to the method without using the event-triggered mechanism.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"314 ","pages":"Article 119582"},"PeriodicalIF":4.6,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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