Pub Date : 2025-11-19DOI: 10.1016/j.apor.2025.104857
Feiyang Huang , Yi Pan , Weiqiu Chen , Jianjin He , Xinqiang Wang , Qingtong Cai , Zhaoyang Hu , Aifeng Tao , Jinhai Zheng
A dike-front Wave Dissipation Basin (WDB) is proposed as an engineering measure to reduce wave overtopping discharge over sea dikes. Flume tests are conducted to quantify the overtopping reduction effectiveness of the WDB and to compare it with other engineering measures. The tests are carried out under various wave conditions, water levels, and cross-sectional sea dike configurations. Comparisons are made among the overtopping reduction performances of a Simple Sloped Dike (SSD), a sea dike with a wave dissipation berm, an SSD with WDBs of different lengths, an SSD with a detached breakwater (BW), and an SSD with a Stilling Wave Basin (SWB). Results demonstrate that the application of the WDB leads to significantly lower overtopping discharge across a wide range of relative crest freeboards, including both negative and positive values. Empirical equations are proposed to estimate the overtopping reduction coefficient of the WDB. A comprehensive comparison is made among the functional characteristics of four types of engineering measures, i.e. WDB, berm, BW, and SWB. The findings of this study on the dike-front WDB present a promising approach to enhancing the resilience of sea dikes.
{"title":"Comparative study on wave overtopping reduction performance on a novel dike-front wave dissipation basin and other engineering measures","authors":"Feiyang Huang , Yi Pan , Weiqiu Chen , Jianjin He , Xinqiang Wang , Qingtong Cai , Zhaoyang Hu , Aifeng Tao , Jinhai Zheng","doi":"10.1016/j.apor.2025.104857","DOIUrl":"10.1016/j.apor.2025.104857","url":null,"abstract":"<div><div>A dike-front Wave Dissipation Basin (WDB) is proposed as an engineering measure to reduce wave overtopping discharge over sea dikes. Flume tests are conducted to quantify the overtopping reduction effectiveness of the WDB and to compare it with other engineering measures. The tests are carried out under various wave conditions, water levels, and cross-sectional sea dike configurations. Comparisons are made among the overtopping reduction performances of a Simple Sloped Dike (SSD), a sea dike with a wave dissipation berm, an SSD with WDBs of different lengths, an SSD with a detached breakwater (BW), and an SSD with a Stilling Wave Basin (SWB). Results demonstrate that the application of the WDB leads to significantly lower overtopping discharge across a wide range of relative crest freeboards, including both negative and positive values. Empirical equations are proposed to estimate the overtopping reduction coefficient of the WDB. A comprehensive comparison is made among the functional characteristics of four types of engineering measures, i.e. WDB, berm, BW, and SWB. The findings of this study on the dike-front WDB present a promising approach to enhancing the resilience of sea dikes.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104857"},"PeriodicalIF":4.4,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576258","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}
In this paper, a new concept of the floating breakwater with zigzag geometry on the seaside of the floating breakwater body was studied numerically. The hydrodynamic analysis of the zigzag floating breakwater has been investigated using the boundary element method based on the three-dimensional diffraction radiation theory. The zigzag floating breakwater was designed by deforming the seaside wall of the breakwater with three different zigzag angles (60, 90, and 120 degrees). The numerical model was validated against experimental data from a pontoon-type breakwater, demonstrating strong agreement with a root mean square error (RMSE) of 0.093 for the transmission coefficient. The RMSE values for sway, heave, and roll response amplitude operators were 0.28, 0.20, and 0.34, respectively, confirming the reliability of the model. The results revealed that the zigzag geometry significantly increases turbulence within the wave field, disrupting typical wave reflection patterns and enhancing energy dissipation due to the greater upstream surface area of the breakwater compared to conventional straight breakwaters. Notably, the 90° zigzag configuration with a middle heave plate exhibited superior performance, achieving a transmission coefficient of 0.28 at w²B/2g = 0.8, compared to 0.84 for a conventional rectangular breakwater. At higher frequencies (w²B/2g ≥ 1.1), the 90° zigzag breakwater with a heave plate further outperformed other designs, achieving a Ct of 0.15 at w²B/2 g = 1.43, compared to 0.44 for the rectangular breakwater. The inclusion of the heave plate was found to enhance performance for mid-range wave conditions but had minimal impact during longer wave periods. For shorter wave periods, the zigzag design demonstrated significant advantages over traditional configurations, particularly in reducing wave transmission.
{"title":"Numerical analysis to consider effect of zigzag floating breakwater geometry on its performance","authors":"Seyed Mohammadreza Tabatabaee Fard , Mohammad Javad Ketabdari , Hamid Reza Ghafari","doi":"10.1016/j.apor.2025.104855","DOIUrl":"10.1016/j.apor.2025.104855","url":null,"abstract":"<div><div>In this paper, a new concept of the floating breakwater with zigzag geometry on the seaside of the floating breakwater body was studied numerically. The hydrodynamic analysis of the zigzag floating breakwater has been investigated using the boundary element method based on the three-dimensional diffraction radiation theory. The zigzag floating breakwater was designed by deforming the seaside wall of the breakwater with three different zigzag angles (60, 90, and 120 degrees). The numerical model was validated against experimental data from a pontoon-type breakwater, demonstrating strong agreement with a root mean square error (RMSE) of 0.093 for the transmission coefficient. The RMSE values for sway, heave, and roll response amplitude operators were 0.28, 0.20, and 0.34, respectively, confirming the reliability of the model. The results revealed that the zigzag geometry significantly increases turbulence within the wave field, disrupting typical wave reflection patterns and enhancing energy dissipation due to the greater upstream surface area of the breakwater compared to conventional straight breakwaters. Notably, the 90° zigzag configuration with a middle heave plate exhibited superior performance, achieving a transmission coefficient of 0.28 at w²B/2g = 0.8, compared to 0.84 for a conventional rectangular breakwater. At higher frequencies (w²B/2<em>g</em> ≥ 1.1), the 90° zigzag breakwater with a heave plate further outperformed other designs, achieving a Ct of 0.15 at w²B/2 <em>g</em> = 1.43, compared to 0.44 for the rectangular breakwater. The inclusion of the heave plate was found to enhance performance for mid-range wave conditions but had minimal impact during longer wave periods. For shorter wave periods, the zigzag design demonstrated significant advantages over traditional configurations, particularly in reducing wave transmission.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104855"},"PeriodicalIF":4.4,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576197","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 : 2025-11-14DOI: 10.1016/j.apor.2025.104856
Zohreh Mousavi , Ru-Ming Feng , Mohammadreza Farhadi , Mir Mohammad Ettefagh , Meysam Bayat , Sina Varahram , Wei-Qiang Feng
Offshore structures, such as monopile Offshore Wind Turbines (OWTs), are subjected to various dynamic loads including waves, wind, and operational vibrations, which can lead to different types of damage. A key consideration in Structural Health Monitoring (SHM) for offshore structures is how soil-structure interaction influences vibration-based damage detection systems. Extracting features manually from vibration signals is often complex, time-consuming, highlighting the need for automatic methods that can learn relevant features straight from raw data. This paper presents a novel vibration-based method for automatic feature learning and damage detection in offshore structures, taking soil interaction into account. A combined deep Convolutional Neural Network and Long Short-Term Memory (CNN-LSTM) network is developed to extract the relevant features from vibration signals reconstructed using the Variational Mode Decomposition (VMD) technique. Integrating the LSTM network with the CNN enhances the detection accuracy and stability while reducing the oscillation. Notably, the proposed method applies VMD-reconstructed vibration signals directly to the deep CNN-LSTM network without requiring separate feature extraction or selection. The VMD technique removes irrelevant components of the vibration signals that do not pertain to the structure’s nature, thereby refining the signals for a more accurate representation of the structure’s condition. The suggested method is verified utilizing experimental data from a lab-scale monopile offshore model that incorporates soil interaction. Vibration data were collected using various accelerometer sensors across different states, including one healthy state and eight damaged states. The results demonstrate that the proposed method effectively learns features from reconstructed vibration data and outperforms comparative methods, making it a promising approach for SHM system development in offshore structures.
{"title":"Enhanced vibration-based damage detection for monopile offshore structures considering soil interaction based on VMD and deep CNN-LSTM","authors":"Zohreh Mousavi , Ru-Ming Feng , Mohammadreza Farhadi , Mir Mohammad Ettefagh , Meysam Bayat , Sina Varahram , Wei-Qiang Feng","doi":"10.1016/j.apor.2025.104856","DOIUrl":"10.1016/j.apor.2025.104856","url":null,"abstract":"<div><div>Offshore structures, such as monopile Offshore Wind Turbines (OWTs), are subjected to various dynamic loads including waves, wind, and operational vibrations, which can lead to different types of damage. A key consideration in Structural Health Monitoring (SHM) for offshore structures is how soil-structure interaction influences vibration-based damage detection systems. Extracting features manually from vibration signals is often complex, time-consuming, highlighting the need for automatic methods that can learn relevant features straight from raw data. This paper presents a novel vibration-based method for automatic feature learning and damage detection in offshore structures, taking soil interaction into account. A combined deep Convolutional Neural Network and Long Short-Term Memory (CNN-LSTM) network is developed to extract the relevant features from vibration signals reconstructed using the Variational Mode Decomposition (VMD) technique. Integrating the LSTM network with the CNN enhances the detection accuracy and stability while reducing the oscillation. Notably, the proposed method applies VMD-reconstructed vibration signals directly to the deep CNN-LSTM network without requiring separate feature extraction or selection. The VMD technique removes irrelevant components of the vibration signals that do not pertain to the structure’s nature, thereby refining the signals for a more accurate representation of the structure’s condition. The suggested method is verified utilizing experimental data from a lab-scale monopile offshore model that incorporates soil interaction. Vibration data were collected using various accelerometer sensors across different states, including one healthy state and eight damaged states. The results demonstrate that the proposed method effectively learns features from reconstructed vibration data and outperforms comparative methods, making it a promising approach for SHM system development in offshore structures.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104856"},"PeriodicalIF":4.4,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526201","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 : 2025-11-13DOI: 10.1016/j.apor.2025.104824
Haifei Chen , Tianyuan Wang , Deborah Greaves , Hongda Shi , Qingping Zou
Interconnected multibody floating structures have gained popularity recently. The dynamic response of moored interconnected floating bodies to wave action, however, are complicated and challenging to model and analyze. To tackle the problem, a novel wave-structure-interaction (WSI) model is developed for the first time by coupling a finite volume CFD model, OpenFOAM, with Project Chrono, a multi-physics simulation engine for multibody dynamics (MBD) and finite element analysis, through linking pre-compiled dynamic libraries. This paper focuses on dynamic behavior of rigid structures restrained with a mooring system. To account for the floating body motion in the fluid solver, both mesh deformation and overset mesh methods are incorporated in the WSI model. The rigid body motion solver integrates two dynamic mooring models (MoorDyn and Moody) to simulate the seakeeping functionality. It also incorporates OpenFAST to simulate the aerodynamics, servo control and structural dynamics of floating offshore wind turbines (FOWTs). The proposed modeling framework is validated and verified against six test cases, ranging from a single floating body such as a floating wind semi-submersible platform and a point absorber wave energy converter (WEC) to a two-body hinged raft. It was found the newly developed WSI modeling framework using only the aforementioned open-source codes achieved the same level of agreement with observations as its commercial counterpart, paving the way for free high-fidelity CFD simulations for the emerging hybrid wind-wave energy and floating solar systems.
{"title":"A new CFD-MBD wave-structure interaction model: Coupling OpenFOAM with Chrono","authors":"Haifei Chen , Tianyuan Wang , Deborah Greaves , Hongda Shi , Qingping Zou","doi":"10.1016/j.apor.2025.104824","DOIUrl":"10.1016/j.apor.2025.104824","url":null,"abstract":"<div><div>Interconnected multibody floating structures have gained popularity recently. The dynamic response of moored interconnected floating bodies to wave action, however, are complicated and challenging to model and analyze. To tackle the problem, a novel wave-structure-interaction (WSI) model is developed for the first time by coupling a finite volume CFD model, OpenFOAM, with Project Chrono, a multi-physics simulation engine for multibody dynamics (MBD) and finite element analysis, through linking pre-compiled dynamic libraries. This paper focuses on dynamic behavior of rigid structures restrained with a mooring system. To account for the floating body motion in the fluid solver, both mesh deformation and overset mesh methods are incorporated in the WSI model. The rigid body motion solver integrates two dynamic mooring models (MoorDyn and Moody) to simulate the seakeeping functionality. It also incorporates OpenFAST to simulate the aerodynamics, servo control and structural dynamics of floating offshore wind turbines (FOWTs). The proposed modeling framework is validated and verified against six test cases, ranging from a single floating body such as a floating wind semi-submersible platform and a point absorber wave energy converter (WEC) to a two-body hinged raft. It was found the newly developed WSI modeling framework using only the aforementioned open-source codes achieved the same level of agreement with observations as its commercial counterpart, paving the way for free high-fidelity CFD simulations for the emerging hybrid wind-wave energy and floating solar systems.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104824"},"PeriodicalIF":4.4,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526203","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 : 2025-11-13DOI: 10.1016/j.apor.2025.104858
Ranjodh Rai , Zhihua Ma , Ling Qian , Wei Bai , Zaibin Lin
This paper presents a new integrated hydrodynamic modelling framework for wave–structure interaction problems. It is developed by coupling a finite-volume-based fully nonlinear potential flow (FNPF) solver with the native OpenFOAM incompressible ‘interFoam’ solver in a numerical wave tank (NWT). The coupling procedure for this new model, named IntegratedFoam, follows a domain decomposition approach in which an overlapping relaxation zone is utilised to implement a one-way coupling. Consequently, the method for transferring information is made simple and the coupling stable due to the primary advantage that each constituent solver has been developed in the same framework of OpenFOAM, and therefore, are both also based on the same numerical method, i.e., the finite-volume method (FVM). This means that only a method to calculate the volume fraction from the free-surface elevation needs to be implemented: the velocity and pressure are already calculated as part of the FNPF solution and can be transferred accordingly. In addition, existing advanced OpenFOAM functionalities can be used for the required interpolation—easily addressing the problem of nonconforming meshes. These functionalities then also allow for the easy implementation of an overlapping relaxation zone which is key to a stable coupling because it ensures that there is a smooth transition from the FNPF to interFoam solution whilst also absorbing any reflected waves in the NWT. The accuracy and efficiency of the new IntegratedFoam model are then systematically validated through two complex wave–structure interaction test cases: focused wave interaction with a fixed 3-D cylinder acting as a simplified monopile foundation and focused wave interaction with a 3-D wave energy converter (WEC) device. It is shown to produce accurate numerical solutions that agree well with existing numerical results and experimental data, all whilst significantly improving computational efficiency.
{"title":"A new integrated numerical wave tank in OpenFOAM for hydrodynamic modelling of offshore renewables","authors":"Ranjodh Rai , Zhihua Ma , Ling Qian , Wei Bai , Zaibin Lin","doi":"10.1016/j.apor.2025.104858","DOIUrl":"10.1016/j.apor.2025.104858","url":null,"abstract":"<div><div>This paper presents a new integrated hydrodynamic modelling framework for wave–structure interaction problems. It is developed by coupling a finite-volume-based fully nonlinear potential flow (FNPF) solver with the native OpenFOAM incompressible ‘interFoam’ solver in a numerical wave tank (NWT). The coupling procedure for this new model, named IntegratedFoam, follows a domain decomposition approach in which an overlapping relaxation zone is utilised to implement a one-way coupling. Consequently, the method for transferring information is made simple and the coupling stable due to the primary advantage that each constituent solver has been developed in the same framework of OpenFOAM, and therefore, are both also based on the same numerical method, i.e., the finite-volume method (FVM). This means that only a method to calculate the volume fraction from the free-surface elevation needs to be implemented: the velocity and pressure are already calculated as part of the FNPF solution and can be transferred accordingly. In addition, existing advanced OpenFOAM functionalities can be used for the required interpolation—easily addressing the problem of nonconforming meshes. These functionalities then also allow for the easy implementation of an overlapping relaxation zone which is key to a stable coupling because it ensures that there is a smooth transition from the FNPF to interFoam solution whilst also absorbing any reflected waves in the NWT. The accuracy and efficiency of the new IntegratedFoam model are then systematically validated through two complex wave–structure interaction test cases: focused wave interaction with a fixed 3-D cylinder acting as a simplified monopile foundation and focused wave interaction with a 3-D wave energy converter (WEC) device. It is shown to produce accurate numerical solutions that agree well with existing numerical results and experimental data, all whilst significantly improving computational efficiency.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104858"},"PeriodicalIF":4.4,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526202","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 : 2025-11-12DOI: 10.1016/j.apor.2025.104835
Yinghui Tian , Wanchao Wu , Mark J. Cassidy
This paper presents a generalised analytical solution for pipeline walking under cyclic temperature and internal pressure variations, incorporating elastoplastic soil resistance. The governing equations are formulated in incremental form, and a closed-form analytical solution is derived. Previously published analytical models that assume rigid plastic soil behaviour are shown to be a special case of this generalised framework, recovered by setting the elastic mobilisation distance to zero. A simplified mathematical expression for pipeline walking rate is obtained, enabling efficient predictions. Calculation examples based on realistic offshore conditions demonstrate the application of the solution in assessing the complete history of pipeline walking. Furthermore, a sensitivity analysis highlights the influence of key parameters on walking behaviour, providing insights for offshore pipeline design and stability assessment.
{"title":"A generalised analytical solution for pipeline walking considering soil resistance as elastoplastic behaviour","authors":"Yinghui Tian , Wanchao Wu , Mark J. Cassidy","doi":"10.1016/j.apor.2025.104835","DOIUrl":"10.1016/j.apor.2025.104835","url":null,"abstract":"<div><div>This paper presents a generalised analytical solution for pipeline walking under cyclic temperature and internal pressure variations, incorporating elastoplastic soil resistance. The governing equations are formulated in incremental form, and a closed-form analytical solution is derived. Previously published analytical models that assume rigid plastic soil behaviour are shown to be a special case of this generalised framework, recovered by setting the elastic mobilisation distance to zero. A simplified mathematical expression for pipeline walking rate is obtained, enabling efficient predictions. Calculation examples based on realistic offshore conditions demonstrate the application of the solution in assessing the complete history of pipeline walking. Furthermore, a sensitivity analysis highlights the influence of key parameters on walking behaviour, providing insights for offshore pipeline design and stability assessment.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104835"},"PeriodicalIF":4.4,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526204","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 : 2025-11-10DOI: 10.1016/j.apor.2025.104852
Ahmed Abuelyamen , Mariam Nagi Amer , Ahmed K. Alkaabi , Saeed A. Alameri , Imran Afgan
Vortex-induced vibration (VIV) poses significant challenges in engineering. Structures subjected to fluid flows necessitate effective suppression mechanisms to avoid vibrations. This study investigates the ability of a nonlinear energy sink (NES) system to reduce VIV under a variety of reduced velocities (). Over scenarios were examined to assess the impact of NES properties; mass ratio (), spring ratio (), and damping ratio () on the vibrational response of structures using computational fluid dynamics (CFD) simulations utilizing Reynolds-averaged Navier–Stokes () turbulence models. The numerical simulations were validated using experimental data demonstrating excellent agreement with the literature. Vibrational contour maps were developed from the CFD predictions over a wide range of . Our findings indicate that the process of tuning the NES parameters (β, γ, and ξ) can either diminish vibrational amplitudes (), or if not carefully optimized, can amplify them. With optimal NES parameter tuning, an amplitude reduction of was found to be possible. Furthermore, Sobol sensitivity analysis was performed, which revealed that while highly depends on , proper tuning of the in combination with is critical, especially in regimes where parameter interactions become significant. While global optimization is challenging, it is recommended that the optimized NES parameters for the lock-in region differ from those for the lower-branch vibration region.
{"title":"Critical roles of mass, spring, and damping ratios in nonlinear energy sink vortex-induced vibrational control: CFD & optimization","authors":"Ahmed Abuelyamen , Mariam Nagi Amer , Ahmed K. Alkaabi , Saeed A. Alameri , Imran Afgan","doi":"10.1016/j.apor.2025.104852","DOIUrl":"10.1016/j.apor.2025.104852","url":null,"abstract":"<div><div>Vortex-induced vibration (VIV) poses significant challenges in engineering. Structures subjected to fluid flows necessitate effective suppression mechanisms to avoid vibrations. This study investigates the ability of a nonlinear energy sink (NES) system to reduce VIV under a variety of reduced velocities (<span><math><mrow><mi>U</mi><mi>r</mi></mrow></math></span>). Over <span><math><mrow><mn>3</mn><mo>,</mo><mn>000</mn></mrow></math></span> scenarios were examined to assess the impact of NES properties; mass ratio (<span><math><mrow><mi>β</mi><mo>=</mo><mn>0.01</mn><mo>−</mo><mn>0.5</mn></mrow></math></span>), spring ratio (<span><math><mrow><mi>γ</mi><mo>=</mo><mn>0.01</mn><mo>−</mo><mn>2.0</mn></mrow></math></span>), and damping ratio (<span><math><mrow><mi>ξ</mi><mo>=</mo><mn>0.01</mn><mo>−</mo><mn>2.0</mn></mrow></math></span>) on the vibrational response of structures using computational fluid dynamics (CFD) simulations utilizing Reynolds-averaged Navier–Stokes (<span><math><mrow><mi>R</mi><mi>A</mi><mi>N</mi><mi>S</mi></mrow></math></span>) turbulence models. The numerical simulations were validated using experimental data demonstrating excellent agreement with the literature. Vibrational contour maps were developed from the CFD predictions over a wide range of <span><math><mrow><mi>U</mi><mi>r</mi><mo>,</mo><mspace></mspace><mi>β</mi><mo>,</mo><mspace></mspace><mi>γ</mi><mo>,</mo><mspace></mspace><mi>a</mi><mi>n</mi><mi>d</mi><mspace></mspace><mi>ξ</mi></mrow></math></span>. Our findings indicate that the process of tuning the NES parameters (β, γ, and ξ) can either diminish vibrational amplitudes (<span><math><mrow><mi>A</mi><mi>y</mi><mo>/</mo><mi>D</mi></mrow></math></span>), or if not carefully optimized, can amplify them. With optimal NES parameter tuning, an amplitude reduction of <span><math><mrow><mn>94</mn><mo>%</mo></mrow></math></span> was found to be possible. Furthermore, Sobol sensitivity analysis was performed, which revealed that while <span><math><mrow><mi>A</mi><mi>y</mi><mo>/</mo><mi>D</mi></mrow></math></span> highly depends on <span><math><mrow><mi>U</mi><mi>r</mi></mrow></math></span>, proper tuning of the <span><math><mi>β</mi></math></span> in combination with <span><math><mi>γ</mi></math></span> is critical, especially in regimes where parameter interactions become significant. While global optimization is challenging, it is recommended that the optimized NES parameters for the lock-in region differ from those for the lower-branch vibration region.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104852"},"PeriodicalIF":4.4,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526207","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 : 2025-11-10DOI: 10.1016/j.apor.2025.104853
X. Feng , J. Chen , Z. Liu , Z. Zhang , Y. Li
Ocean extreme waves are of both scientific and engineering interests. These extreme waves pose great threats to the safety of coastal and offshore structures. They are highly nonlinear and transient in a real sea state. It is important to study their nonlinear effects for accurate prediction of them. In this study, a focused wave group is used to investigate the nonlinear properties in such transient extreme event experimentally and numerically. An experimental campaign is carried out in a large wave tank facility, and a fully nonlinear potential flow model is employed for numerical simulations. A phase-manipulation approach is applied on wave generation in order to extract clean higher harmonic wave elevations. Comparisons between the measurements and the numerical results show good agreements for higher harmonic elevations. The non-dimensional harmonic coefficients, based on a ‘Stokes-type’ harmonic structure, are found to increase gradually with the wave steepness. This suggests that the classical Stokes model might be used for nonlinear wave group prediction, given proper harmonic coefficients. To further investigate the nonlinear effects, the asymmetric properties of the wave profiles near focusing are explored by analysing the preceding and following wave crests. Clear nonlinearity is demonstrated by evaluating the wave envelope height and group bandwidth.
{"title":"Nonlinear effects on wave elevation of a focused water wave group","authors":"X. Feng , J. Chen , Z. Liu , Z. Zhang , Y. Li","doi":"10.1016/j.apor.2025.104853","DOIUrl":"10.1016/j.apor.2025.104853","url":null,"abstract":"<div><div>Ocean extreme waves are of both scientific and engineering interests. These extreme waves pose great threats to the safety of coastal and offshore structures. They are highly nonlinear and transient in a real sea state. It is important to study their nonlinear effects for accurate prediction of them. In this study, a focused wave group is used to investigate the nonlinear properties in such transient extreme event experimentally and numerically. An experimental campaign is carried out in a large wave tank facility, and a fully nonlinear potential flow model is employed for numerical simulations. A phase-manipulation approach is applied on wave generation in order to extract clean higher harmonic wave elevations. Comparisons between the measurements and the numerical results show good agreements for higher harmonic elevations. The non-dimensional harmonic coefficients, based on a ‘Stokes-type’ harmonic structure, are found to increase gradually with the wave steepness. This suggests that the classical Stokes model might be used for nonlinear wave group prediction, given proper harmonic coefficients. To further investigate the nonlinear effects, the asymmetric properties of the wave profiles near focusing are explored by analysing the preceding and following wave crests. Clear nonlinearity is demonstrated by evaluating the wave envelope height and group bandwidth.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104853"},"PeriodicalIF":4.4,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526205","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 : 2025-11-07DOI: 10.1016/j.apor.2025.104844
JeongYong Park , Ikjae Lee , MooHyun Kim , Chungkuk Jin , Ipsita Mishra , D. Todd Griffith , Mario A. Rotea
Mooring line failure in Floating Offshore Wind Turbines (FOWTs) threatens safety, power production, and nearby structures. This study develops an automated detection framework that combines hull motion sensors with machine learning (ML). A synthetic dataset for the 15MW VolturnUS-S semi-submersible FOWT was created using OpenFAST under intact and failed mooring conditions across 79 wind and wave scenarios. The mean and standard deviation of six degree of freedom (6DOF) motions including surge, sway, heave, roll, pitch, and yaw were used as input features. Different sensor configurations such as inertial measurement units (IMU) and differential GPS (DGPS) were tested under added noise. Artificial neural networks (ANN), random forests (RF), and support vector machines (SVM) were evaluated with optimized hyperparameters. All models achieved excellent accuracy, with RF performing best. However, using raw IMU signals without displacement conversion reduces prediction accuracy due to missing mean offset information. The results demonstrate a reliable approach for near-real-time mooring-integrity monitoring that improves safety while reducing reliance on expensive equipment.
{"title":"Automatic Mooring-Line-Failure Detection Using Hull Motion Sensors and Machine Learning (ML) for 15MW Floating Offshore Wind Turbines (FOWTs)","authors":"JeongYong Park , Ikjae Lee , MooHyun Kim , Chungkuk Jin , Ipsita Mishra , D. Todd Griffith , Mario A. Rotea","doi":"10.1016/j.apor.2025.104844","DOIUrl":"10.1016/j.apor.2025.104844","url":null,"abstract":"<div><div>Mooring line failure in Floating Offshore Wind Turbines (FOWTs) threatens safety, power production, and nearby structures. This study develops an automated detection framework that combines hull motion sensors with machine learning (ML). A synthetic dataset for the 15MW VolturnUS-S semi-submersible FOWT was created using OpenFAST under intact and failed mooring conditions across 79 wind and wave scenarios. The mean and standard deviation of six degree of freedom (6DOF) motions including surge, sway, heave, roll, pitch, and yaw were used as input features. Different sensor configurations such as inertial measurement units (IMU) and differential GPS (DGPS) were tested under added noise. Artificial neural networks (ANN), random forests (RF), and support vector machines (SVM) were evaluated with optimized hyperparameters. All models achieved excellent accuracy, with RF performing best. However, using raw IMU signals without displacement conversion reduces prediction accuracy due to missing mean offset information. The results demonstrate a reliable approach for near-real-time mooring-integrity monitoring that improves safety while reducing reliance on expensive equipment.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104844"},"PeriodicalIF":4.4,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463565","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 : 2025-11-07DOI: 10.1016/j.apor.2025.104847
Nguyen Q. Chien , Connor Jordan , Emils Brazovskis , Brian Sellar , João Ribeiro , Adélio Silva , Athanasios Angeloudis
Operational ocean models are widely applied for Earth and ocean observation for real-time predictions of ocean processes at large scales. Adaptations of these systems could cater more specific engineering and finer, metre-scale, applications. With this in mind, we consider the operational modelling for tidal stream turbine arrays, where multiple scales of coastal ocean hydrodynamics must be reconciled to facilitate the conversion of hydrokinetic energy. In monitoring an array’s performance, impact, and ocean interactions, an operational modelling system must resolve both metocean forcing from tens of kilometres away and fine-scale flow patterns around individual turbines. This study demonstrates the functionality, utility, and sensitivity of such a system to support the design of tidal arrays. We focus on a turbine array operating in the Pentland Firth, Scotland. The tidal array operational model is designed to operate in real-time, allows web clients to ingest data, and returns design data summarised and visualised in a web dashboard, alongside a series of appropriate metrics. We note significant trade-offs with respect to the modelling setup balancing resolution and accuracy against measured data. We also demonstrate the value of multi-scale ocean modelling from an operational perspective, which focuses computational effort where it is most needed to deliver near-real-time information reliably.
{"title":"Operational coastal ocean modelling for tidal stream turbine arrays","authors":"Nguyen Q. Chien , Connor Jordan , Emils Brazovskis , Brian Sellar , João Ribeiro , Adélio Silva , Athanasios Angeloudis","doi":"10.1016/j.apor.2025.104847","DOIUrl":"10.1016/j.apor.2025.104847","url":null,"abstract":"<div><div>Operational ocean models are widely applied for Earth and ocean observation for real-time predictions of ocean processes at large scales. Adaptations of these systems could cater more specific engineering and finer, metre-scale, applications. With this in mind, we consider the operational modelling for tidal stream turbine arrays, where multiple scales of coastal ocean hydrodynamics must be reconciled to facilitate the conversion of hydrokinetic energy. In monitoring an array’s performance, impact, and ocean interactions, an operational modelling system must resolve both metocean forcing from tens of kilometres away and fine-scale flow patterns around individual turbines. This study demonstrates the functionality, utility, and sensitivity of such a system to support the design of tidal arrays. We focus on a turbine array operating in the Pentland Firth, Scotland. The tidal array operational model is designed to operate in real-time, allows web clients to ingest data, and returns design data summarised and visualised in a web dashboard, alongside a series of appropriate metrics. We note significant trade-offs with respect to the modelling setup balancing resolution and accuracy against measured data. We also demonstrate the value of multi-scale ocean modelling from an operational perspective, which focuses computational effort where it is most needed to deliver near-real-time information reliably.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"165 ","pages":"Article 104847"},"PeriodicalIF":4.4,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463514","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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