Xueliang Wen, Jianan Zhang, Alejandro Garcia Conde, Muk Chen Ong
Abstract The ballast control of a floating dock mainly relies on manual operations, which can be time-consuming and requires skilled workers. This study proposes an automatic ballast control system for floating docks, which improves operational efficiency and safety during the vessel docking process. A numerical model is developed to simulate the dynamic process of the floating dock's operations, which includes a six-degree-of-freedom (6-DOF) model, a hydrostatic force model, a hydrodynamic force model, and a hydraulic model. The hydrostatic force model is developed using the Archimedes law and a strip theory along the longitudinal direction. The hydrodynamic model is made based on the effects of added mass and dynamic damping. The hydraulic model is proposed to deal with the hydraulic calculation of the ballast water system. The present automatic ballast control is designed based on a modified proportional controller (P-controller) to control the valve opening angles when the pitch or roll angles are larger than the corresponding threshold values. Without using controllers, the roll angles of the dock can reach 8.9deg and 13deg during the ballasting and de-ballasting operations, respectively. The present modified P-controller with optimized control parameters can stabilize the dock during the ballasting and de-ballasting operations and keep the maximum pitch and roll angles no larger than 0.016deg and 0.0783deg, respectively. The present automatic control will be further implemented in the vessel docking cases and can significantly improve the stability of the dock.
{"title":"Numerical Study on the Automatic Ballast Control of a Floating Dock","authors":"Xueliang Wen, Jianan Zhang, Alejandro Garcia Conde, Muk Chen Ong","doi":"10.1115/1.4064014","DOIUrl":"https://doi.org/10.1115/1.4064014","url":null,"abstract":"Abstract The ballast control of a floating dock mainly relies on manual operations, which can be time-consuming and requires skilled workers. This study proposes an automatic ballast control system for floating docks, which improves operational efficiency and safety during the vessel docking process. A numerical model is developed to simulate the dynamic process of the floating dock's operations, which includes a six-degree-of-freedom (6-DOF) model, a hydrostatic force model, a hydrodynamic force model, and a hydraulic model. The hydrostatic force model is developed using the Archimedes law and a strip theory along the longitudinal direction. The hydrodynamic model is made based on the effects of added mass and dynamic damping. The hydraulic model is proposed to deal with the hydraulic calculation of the ballast water system. The present automatic ballast control is designed based on a modified proportional controller (P-controller) to control the valve opening angles when the pitch or roll angles are larger than the corresponding threshold values. Without using controllers, the roll angles of the dock can reach 8.9deg and 13deg during the ballasting and de-ballasting operations, respectively. The present modified P-controller with optimized control parameters can stabilize the dock during the ballasting and de-ballasting operations and keep the maximum pitch and roll angles no larger than 0.016deg and 0.0783deg, respectively. The present automatic control will be further implemented in the vessel docking cases and can significantly improve the stability of the dock.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"46 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135474730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Peridynamic theory is the reformulation of classical mechanics mathematical theory compatible with cracks while performing structural analysis. The present study models the tubular joints having T, Y, K, and X configurations in the peridynamic framework by implementing peridynamic shell governing equations. The magnitude of deformations under static loading and the displacement variation at the subsequent load steps varying in a sinusoidal and irregular manner are validated. The crack initiation location at the stress-concentrated region and the crack growth path leading to fracture under linearly increasing loads for the considered tubular joints can be inferred from this approach. A comparative study is performed among the joint configurations based on the linear displacement variation and critical loads for the unstable deformation due to damaged material points at the joint intersection. In the present paper, apart from validating the implementation of novel theory in the offshore structure, the drawbacks and intricacies of the classical approach for studying crack initiation and growth in complex tubular joint structures are resolved by the peridynamic approach.
{"title":"PEridynamic Analysis of Tubular Joints of Offshore Jacket Structure","authors":"Pranitha Bachimanchi, Nilanjan Saha","doi":"10.1115/1.4064015","DOIUrl":"https://doi.org/10.1115/1.4064015","url":null,"abstract":"Abstract Peridynamic theory is the reformulation of classical mechanics mathematical theory compatible with cracks while performing structural analysis. The present study models the tubular joints having T, Y, K, and X configurations in the peridynamic framework by implementing peridynamic shell governing equations. The magnitude of deformations under static loading and the displacement variation at the subsequent load steps varying in a sinusoidal and irregular manner are validated. The crack initiation location at the stress-concentrated region and the crack growth path leading to fracture under linearly increasing loads for the considered tubular joints can be inferred from this approach. A comparative study is performed among the joint configurations based on the linear displacement variation and critical loads for the unstable deformation due to damaged material points at the joint intersection. In the present paper, apart from validating the implementation of novel theory in the offshore structure, the drawbacks and intricacies of the classical approach for studying crack initiation and growth in complex tubular joint structures are resolved by the peridynamic approach.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"76 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135433119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Subramanian Keerthi Raaj, Vijay K G, Neelamani Subramaniam, Nilanjan Saha, R Sundaravadivelu
Abstract Surface gravity wave interaction with a novel composite pile-rock breakwater having a stack of porous plates fixed on its top is investigated in the present study. A novel numerical code based on dual-boundary-element-method is developed to understand the wave scattering and force coefficients within framework of linearized potential flow theory. Out of the four different proposed configurations (pile-rock alone, vertical, horizontal, and H-shaped porous plate assembly with pile-rock), it is found that a novel H-shaped porous plates with submerged pile-rock are very effective in attenuating the wave energy. The parametric study for the H-shaped configuration with several key aspects like porosity of the permeable plates, submergence depth of the horizontal plate, pile-rock relative height and width of the pile-rock barriers are investigated. Increasing relative rock barrier width from 0.25-0.75 offers only a marginal reduction in wave transmission but increases the vertical wave force on the H-plate barrier almost twice. By changing relative submergence of the horizontal porous plate from, it is possible to reduce wave transmission by about 10% but at the expense of increasing vertical wave force almost 50%-75%. Increasing the pile-rock height helps to reduce the wave transmission but significantly increases horizontal wave force and moment on perforated H-shaped barrier. The results of the parametric study can be used for optimizing the dimensions of pile-rock cum porous plate wave barrier for a wide range of field conditions.
{"title":"Gravity wave interaction with a composite pile-rock breakwater","authors":"Subramanian Keerthi Raaj, Vijay K G, Neelamani Subramaniam, Nilanjan Saha, R Sundaravadivelu","doi":"10.1115/1.4064013","DOIUrl":"https://doi.org/10.1115/1.4064013","url":null,"abstract":"Abstract Surface gravity wave interaction with a novel composite pile-rock breakwater having a stack of porous plates fixed on its top is investigated in the present study. A novel numerical code based on dual-boundary-element-method is developed to understand the wave scattering and force coefficients within framework of linearized potential flow theory. Out of the four different proposed configurations (pile-rock alone, vertical, horizontal, and H-shaped porous plate assembly with pile-rock), it is found that a novel H-shaped porous plates with submerged pile-rock are very effective in attenuating the wave energy. The parametric study for the H-shaped configuration with several key aspects like porosity of the permeable plates, submergence depth of the horizontal plate, pile-rock relative height and width of the pile-rock barriers are investigated. Increasing relative rock barrier width from 0.25-0.75 offers only a marginal reduction in wave transmission but increases the vertical wave force on the H-plate barrier almost twice. By changing relative submergence of the horizontal porous plate from, it is possible to reduce wave transmission by about 10% but at the expense of increasing vertical wave force almost 50%-75%. Increasing the pile-rock height helps to reduce the wave transmission but significantly increases horizontal wave force and moment on perforated H-shaped barrier. The results of the parametric study can be used for optimizing the dimensions of pile-rock cum porous plate wave barrier for a wide range of field conditions.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"338 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135474899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhengsong An, Yong Chen, Wei Huang, Lin Yu, Sihua Deng, Jiayi Liu
Abstract The coupling between fluid-solid interaction and structural response is a crucial factor in understanding the resistance of sandwich structures to underwater blasts. In this study, we present a theoretical model that predicts the dynamic response of multilayer foam core sandwich beams subjected to underwater impulses. We carried out a time-scale intercoupling analysis by considering the compressible core in both incident impulse and structural response. In the incident impulse coupling phase, the one-dimensional fluid-structure interaction in terms of cavitation evolution is conducted to obtain the incident pressure profile. A four inter-stages response model is proposed for further analyze the structural response coupling phase and its coupling with core strength. Explicit finite element calculations are performed to verify the theoretical results in terms of the velocity profile, transverse deflection, and core compression. The results suggest that the interaction between the four stages of the dynamic response is significantly influenced by the impulsive intensity and core strength, and the sandwich beam does not undergo all the four stages. The equivalent core strength used in the theoretical analysis is confirmed accurate to predicts impact resistance of the corresponding graded core sandwich beam, which is inferior to the sandwich beam with uniform cores, despite having the same areal mass.
{"title":"Underwater impulsive response of sandwich structure with multilayer foam core","authors":"Zhengsong An, Yong Chen, Wei Huang, Lin Yu, Sihua Deng, Jiayi Liu","doi":"10.1115/1.4064016","DOIUrl":"https://doi.org/10.1115/1.4064016","url":null,"abstract":"Abstract The coupling between fluid-solid interaction and structural response is a crucial factor in understanding the resistance of sandwich structures to underwater blasts. In this study, we present a theoretical model that predicts the dynamic response of multilayer foam core sandwich beams subjected to underwater impulses. We carried out a time-scale intercoupling analysis by considering the compressible core in both incident impulse and structural response. In the incident impulse coupling phase, the one-dimensional fluid-structure interaction in terms of cavitation evolution is conducted to obtain the incident pressure profile. A four inter-stages response model is proposed for further analyze the structural response coupling phase and its coupling with core strength. Explicit finite element calculations are performed to verify the theoretical results in terms of the velocity profile, transverse deflection, and core compression. The results suggest that the interaction between the four stages of the dynamic response is significantly influenced by the impulsive intensity and core strength, and the sandwich beam does not undergo all the four stages. The equivalent core strength used in the theoretical analysis is confirmed accurate to predicts impact resistance of the corresponding graded core sandwich beam, which is inferior to the sandwich beam with uniform cores, despite having the same areal mass.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"79 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135433253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Min Gao, Scott Draper, Guy McCauley, Lifen Chen, Xiantao Zhang, Hugh Wolgamot, Paul Taylor, Liang Cheng
Abstract This article uses scaled physical and numerical modeling to investigate an idealized but complicated problem in which green water impacts a circular cylindrical structure located on top of a fixed box representative of a vessel. A focused wave group was used to overtop the box and generate the green water event, which resembled a plunging wave with air entrainment. The plunger collapsed and ran across the deck before impacting and then scattering from the cylinder. To test the adequacy of the physical modeling, nominally identical experiments were conducted in two different laboratories, in different countries. The numerical modeling comprised computational fluid dynamics (CFD) simulations performed using openfoam. The flow features, the force on the cylinder, and the surface elevation on top of the box are compared in detail across the two physical models and the CFD. Consistent load measurements were obtained from the two physical model tests, with force impulse results differing by less than 10%, underscoring the validity of the results, even accounting for the complexity of flow–structure interactions. A comparison with numerical model results reveals some sensitivity to experimental precision in the flow measurements on top of the box and the green water load. Nonetheless, the overall force impulse discrepancy between experiments and numerical models is within 15%, highlighting that the robustness of the methods was used despite these sensitivities. The sensitivity to CFD mesh and iterating the incident wave to match CFD and experiment are also explored. The agreement between experiment and CFD serves as an example of the utility of CFD for modeling green water loads.
{"title":"Modelling Green Water Load on A Deck Mounted Circular Cylinder","authors":"Min Gao, Scott Draper, Guy McCauley, Lifen Chen, Xiantao Zhang, Hugh Wolgamot, Paul Taylor, Liang Cheng","doi":"10.1115/1.4063807","DOIUrl":"https://doi.org/10.1115/1.4063807","url":null,"abstract":"Abstract This article uses scaled physical and numerical modeling to investigate an idealized but complicated problem in which green water impacts a circular cylindrical structure located on top of a fixed box representative of a vessel. A focused wave group was used to overtop the box and generate the green water event, which resembled a plunging wave with air entrainment. The plunger collapsed and ran across the deck before impacting and then scattering from the cylinder. To test the adequacy of the physical modeling, nominally identical experiments were conducted in two different laboratories, in different countries. The numerical modeling comprised computational fluid dynamics (CFD) simulations performed using openfoam. The flow features, the force on the cylinder, and the surface elevation on top of the box are compared in detail across the two physical models and the CFD. Consistent load measurements were obtained from the two physical model tests, with force impulse results differing by less than 10%, underscoring the validity of the results, even accounting for the complexity of flow–structure interactions. A comparison with numerical model results reveals some sensitivity to experimental precision in the flow measurements on top of the box and the green water load. Nonetheless, the overall force impulse discrepancy between experiments and numerical models is within 15%, highlighting that the robustness of the methods was used despite these sensitivities. The sensitivity to CFD mesh and iterating the incident wave to match CFD and experiment are also explored. The agreement between experiment and CFD serves as an example of the utility of CFD for modeling green water loads.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"24 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135769509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tianning Tang, Haoyu Ding, Saishuai Dai, Xi Chen, Paul Taylor, Jun Zang, Thomas AA Adcock
Abstract Model testing is common in coastal and offshore engineering. The design of such model tests is important such that the maximal information of the underlying physics can be extrapolated with a limited amount of test cases. The optimal design of experiments also requires considering the previous similar experimental results and the typical sea-states of the ocean environments. In this study, we develop a model test design strategy based on Bayesian sampling for a classic problem in ocean engineering -- nonlinear wave loading on a vertical cylinder. The new experimental design strategy is achieved through a GP-based surrogate model, which considers the previous experimental data as the prior information. The metocean data are further incorporated into the experimental design through a modified acquisition function. We perform a new experiment, which is mainly designed by data-driven methods including several critical parameters such as the size of the cylinder and all the wave conditions. We examine the performance of such a method when compared to traditional experimental design based on manual decisions. This method is a step forward to a more systematic way of approaching test designs with marginally better performance in capturing the higher-order force coefficients. The current surrogate model also made several ‘interpretable’ decisions which can be explained with physical insights.
{"title":"Data Informed Model Test Design With Machine Learning – an Example in Nonlinear Wave Load on a Vertical Cylinder","authors":"Tianning Tang, Haoyu Ding, Saishuai Dai, Xi Chen, Paul Taylor, Jun Zang, Thomas AA Adcock","doi":"10.1115/1.4063942","DOIUrl":"https://doi.org/10.1115/1.4063942","url":null,"abstract":"Abstract Model testing is common in coastal and offshore engineering. The design of such model tests is important such that the maximal information of the underlying physics can be extrapolated with a limited amount of test cases. The optimal design of experiments also requires considering the previous similar experimental results and the typical sea-states of the ocean environments. In this study, we develop a model test design strategy based on Bayesian sampling for a classic problem in ocean engineering -- nonlinear wave loading on a vertical cylinder. The new experimental design strategy is achieved through a GP-based surrogate model, which considers the previous experimental data as the prior information. The metocean data are further incorporated into the experimental design through a modified acquisition function. We perform a new experiment, which is mainly designed by data-driven methods including several critical parameters such as the size of the cylinder and all the wave conditions. We examine the performance of such a method when compared to traditional experimental design based on manual decisions. This method is a step forward to a more systematic way of approaching test designs with marginally better performance in capturing the higher-order force coefficients. The current surrogate model also made several ‘interpretable’ decisions which can be explained with physical insights.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"25 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136067592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In general, submarines are designed to optimize operation below the water surface because they spend most of their time underwater. On the other hand, the performance in the free surface condition is also important because submarines face a variety of scenarios to complete operational missions, and the free surface condition is unavoidable for port departure and arrival. In the case of a submarine, the numerical accuracy of the potential theory for seakeeping analysis is excellent in submerged conditions, but it is poor in free surface conditions because of nonlinear effects near the free surface area. In this study, Star-CCM+ was used as a Reynolds-averaged Navier Stokes (RANS) solver to estimate the seakeeping performance of a Canadian Victoria Class submarine in irregular waves. The results were compared with those of model tests from a published paper. In addition, the potential theory code was also used to assess the seakeeping performance and compare with Computational Fluid Dynamics (CFD) results. From the calculation results, the motion responses in irregular waves using CFD showed similar trends to the experimental results. In contrast, motion responses from potential code showed significantly larger values than the experimental results. In conclusion, CFD simulations with irregular waves can be a good solution to predict the seakeeping performance of submarines in free surface conditions.
{"title":"A computational study to predict the seakeeping performance of a surfaced submarine in irregular waves","authors":"Jung Doojin, Sanghyun Kim","doi":"10.1115/1.4063940","DOIUrl":"https://doi.org/10.1115/1.4063940","url":null,"abstract":"Abstract In general, submarines are designed to optimize operation below the water surface because they spend most of their time underwater. On the other hand, the performance in the free surface condition is also important because submarines face a variety of scenarios to complete operational missions, and the free surface condition is unavoidable for port departure and arrival. In the case of a submarine, the numerical accuracy of the potential theory for seakeeping analysis is excellent in submerged conditions, but it is poor in free surface conditions because of nonlinear effects near the free surface area. In this study, Star-CCM+ was used as a Reynolds-averaged Navier Stokes (RANS) solver to estimate the seakeeping performance of a Canadian Victoria Class submarine in irregular waves. The results were compared with those of model tests from a published paper. In addition, the potential theory code was also used to assess the seakeeping performance and compare with Computational Fluid Dynamics (CFD) results. From the calculation results, the motion responses in irregular waves using CFD showed similar trends to the experimental results. In contrast, motion responses from potential code showed significantly larger values than the experimental results. In conclusion, CFD simulations with irregular waves can be a good solution to predict the seakeeping performance of submarines in free surface conditions.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"942 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136067758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Thin porous plates serve as an effective model for the construction of breakwater. Thus, the problem involving oblique wave interaction with a tunnel in the presence of a submerged horizontal porous plate over a trench-type bottom is investigated. In this paper, for the mathematical formulation of the physical model, water wave potentials are defined using Havelock's expansions and flow past over porous structure is modelled based on Darcy's law. The advantage of the trench type of bottom and horizontal plate are studied through the numerical results of forces on the tunnel. The study reveals that more energy loss and less force on the tunnel are obtained if the porous effect parameter of the plate or the length of the plate is increased up to a moderated value of these parameters. Compared to the case without porous plate and trench-type bottom topography, there are significant changes in forces due to this porous breakwater and trench-type bottom topography. In addition, from the present results, it may be noted that the load on the submerged tunnel is reduced by adding a submerged horizontal porous plate and asymmetric trench, which is helpful in understanding the role of porous breakwaters and trenches in applications to Ocean and Coastal Engineering.
{"title":"Mitigation of wave force on a tunnel in the presence of submerged porous plate over trench-type bottom topography","authors":"Sunita Choudhary, S. C. Martha","doi":"10.1115/1.4063943","DOIUrl":"https://doi.org/10.1115/1.4063943","url":null,"abstract":"Abstract Thin porous plates serve as an effective model for the construction of breakwater. Thus, the problem involving oblique wave interaction with a tunnel in the presence of a submerged horizontal porous plate over a trench-type bottom is investigated. In this paper, for the mathematical formulation of the physical model, water wave potentials are defined using Havelock's expansions and flow past over porous structure is modelled based on Darcy's law. The advantage of the trench type of bottom and horizontal plate are studied through the numerical results of forces on the tunnel. The study reveals that more energy loss and less force on the tunnel are obtained if the porous effect parameter of the plate or the length of the plate is increased up to a moderated value of these parameters. Compared to the case without porous plate and trench-type bottom topography, there are significant changes in forces due to this porous breakwater and trench-type bottom topography. In addition, from the present results, it may be noted that the load on the submerged tunnel is reduced by adding a submerged horizontal porous plate and asymmetric trench, which is helpful in understanding the role of porous breakwaters and trenches in applications to Ocean and Coastal Engineering.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"8 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136068114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Junyi Liu, Xujun Chen, Song Ji, Heng Huang, Xi Chen, Qunzhang Tu
Abstract A two-dimensional model to estimate the hydrodynamic response of hinged multiple floating body system in time domain is established based on the Kane method. The reduced Kane equations applicable to the dynamic response of multi-floating body system with hinges are firstly deduced. The issue of hinge constraint in the system is addressed by defining the corresponding generalised speeds as zeros, while the wave actions are considered based on the potential flow theory. Then the corresponding calculation program is developed prior to undertaking the model test. Verification of the Kane-based model and the veracity of the program developed are performed through a series of contrastive analyses on a hinged floating bridge in various cases including regular waves, moving loads and their combinations. The predictions obtained by the proposed model show satisfactory agreements with the model test measurements. The related results indicate that the motion responses of the first pontoon are greatest in hinged floating bridge, and its motion amplitudes descend nonlinearly with the increment of wave frequency. The time-history motion responses of hinged multi-floating bodies in the middle present saddle shapes with some fluctuations as a whole under the combined effect of wave and moving loads. The Kane-based model is convenient to analyse the dynamic characteristics of a hinged multi-floating body system in regular waves, and it could be further extended to consider the effects of irregular waves, inhomogeneous sea conditions as well as the nonlinear connections on the system.
{"title":"A time domain model to predict dynamic response of multiple floating bodies connected with hinges based on the Kane method","authors":"Junyi Liu, Xujun Chen, Song Ji, Heng Huang, Xi Chen, Qunzhang Tu","doi":"10.1115/1.4063944","DOIUrl":"https://doi.org/10.1115/1.4063944","url":null,"abstract":"Abstract A two-dimensional model to estimate the hydrodynamic response of hinged multiple floating body system in time domain is established based on the Kane method. The reduced Kane equations applicable to the dynamic response of multi-floating body system with hinges are firstly deduced. The issue of hinge constraint in the system is addressed by defining the corresponding generalised speeds as zeros, while the wave actions are considered based on the potential flow theory. Then the corresponding calculation program is developed prior to undertaking the model test. Verification of the Kane-based model and the veracity of the program developed are performed through a series of contrastive analyses on a hinged floating bridge in various cases including regular waves, moving loads and their combinations. The predictions obtained by the proposed model show satisfactory agreements with the model test measurements. The related results indicate that the motion responses of the first pontoon are greatest in hinged floating bridge, and its motion amplitudes descend nonlinearly with the increment of wave frequency. The time-history motion responses of hinged multi-floating bodies in the middle present saddle shapes with some fluctuations as a whole under the combined effect of wave and moving loads. The Kane-based model is convenient to analyse the dynamic characteristics of a hinged multi-floating body system in regular waves, and it could be further extended to consider the effects of irregular waves, inhomogeneous sea conditions as well as the nonlinear connections on the system.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"730 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136067597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract An analytical framework is developed to analyze the interaction of oblique waves with multiple flexible porous breakwaters under the consideration of bottom undulation. The mathematical problem is tackled using the small amplitude water-wave theory, with Darcy's law being applied to account for wave interaction with porous media. The bottom topography is considered to have a finite length, flanked by two semi-infinite sections of uniform bottom. The solution to the boundary value problem is approached by employing the eigenfunction expansion method within the uniform bottom regions. For the varying bottom topography, a modified mild-slope equation (MMSE) is utilized. To address the solution at the slope discontinuity at the bottom, a mass-conserving jump condition is applied. By matching solutions at the interfaces, a set of equations is derived. This system of equations encapsulates the behavior of reflection and transmission coefficients, as well as the force exerted on the breakwaters. These parameters are then investigated across various factors, such as the length of the varying bottom, depth ratio, angle of the mooring line, angle of incidence, and flexural rigidity. Graphical representations of the reflection and transmission coefficients, along with the breakwater force, provide insights into the system's behavior under different conditions. The water wave energy can be dissipated for the the optimum values of flexural rigidity. The transmission coefficient is observed to be least for higher mooring angle.
{"title":"Effect of sloping bottom on wave interaction with multiple flexible moored breakwaters","authors":"Saista Tabssum, Balaji Ramakrishnan","doi":"10.1115/1.4063941","DOIUrl":"https://doi.org/10.1115/1.4063941","url":null,"abstract":"Abstract An analytical framework is developed to analyze the interaction of oblique waves with multiple flexible porous breakwaters under the consideration of bottom undulation. The mathematical problem is tackled using the small amplitude water-wave theory, with Darcy's law being applied to account for wave interaction with porous media. The bottom topography is considered to have a finite length, flanked by two semi-infinite sections of uniform bottom. The solution to the boundary value problem is approached by employing the eigenfunction expansion method within the uniform bottom regions. For the varying bottom topography, a modified mild-slope equation (MMSE) is utilized. To address the solution at the slope discontinuity at the bottom, a mass-conserving jump condition is applied. By matching solutions at the interfaces, a set of equations is derived. This system of equations encapsulates the behavior of reflection and transmission coefficients, as well as the force exerted on the breakwaters. These parameters are then investigated across various factors, such as the length of the varying bottom, depth ratio, angle of the mooring line, angle of incidence, and flexural rigidity. Graphical representations of the reflection and transmission coefficients, along with the breakwater force, provide insights into the system's behavior under different conditions. The water wave energy can be dissipated for the the optimum values of flexural rigidity. The transmission coefficient is observed to be least for higher mooring angle.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":"53 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136067764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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