Pub Date : 2024-11-06DOI: 10.1016/j.apor.2024.104293
Jixin Liu , Ze Yu , Fei Yu , Tianhong Yan , Bo He
A novel method is proposed to predict the hydrodynamic and acoustic properties of propeller boss cap fins (PBCF) based on computational fluid dynamics (CFD) and surrogate models. The propulsive performance and radiated noise of the B-series propeller equipped with PBCF under open-water and hull-propeller coupling conditions are predicted and analyzed. The transient calculations are performed to generate accurate sample data for the surrogate model based on the Unsteady Reynolds Averaged Navier–Stokes and Ffowcs Williams–Hawkings equations. The response surface, polynomial, and Kriging models are used to learn sample data and output predictions. The relationship between inputs and outputs can be established from local data, which enables to obtain arbitrary response results in the global range. The hydrodynamic performance and radiated noise are compared for configurations with and without PBCF. PBCF improves the open-water efficiency by more than 1.5% at medium to high advance velocities. For the self-propulsion efficiency, over 5% improvement is achieved under ideal working conditions. In addition, PBCF has a directional effect on the radial and axial radiated noise, with better noise reduction in the axial direction. The difference between the axial and radial spectrums is significant, especially near the first blade passing frequency.
{"title":"Computational fluid dynamics driven surrogate model to predict hydrodynamic and acoustic properties of propeller boss cap fins","authors":"Jixin Liu , Ze Yu , Fei Yu , Tianhong Yan , Bo He","doi":"10.1016/j.apor.2024.104293","DOIUrl":"10.1016/j.apor.2024.104293","url":null,"abstract":"<div><div>A novel method is proposed to predict the hydrodynamic and acoustic properties of propeller boss cap fins (PBCF) based on computational fluid dynamics (CFD) and surrogate models. The propulsive performance and radiated noise of the B-series propeller equipped with PBCF under open-water and hull-propeller coupling conditions are predicted and analyzed. The transient calculations are performed to generate accurate sample data for the surrogate model based on the Unsteady Reynolds Averaged Navier–Stokes and Ffowcs Williams–Hawkings equations. The response surface, polynomial, and Kriging models are used to learn sample data and output predictions. The relationship between inputs and outputs can be established from local data, which enables to obtain arbitrary response results in the global range. The hydrodynamic performance and radiated noise are compared for configurations with and without PBCF. PBCF improves the open-water efficiency by more than 1.5% at medium to high advance velocities. For the self-propulsion efficiency, over 5% improvement is achieved under ideal working conditions. In addition, PBCF has a directional effect on the radial and axial radiated noise, with better noise reduction in the axial direction. The difference between the axial and radial spectrums is significant, especially near the first blade passing frequency.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104293"},"PeriodicalIF":4.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659262","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.apor.2024.104292
Jinah Kim , Taekyung Kim , Miyoung Yun , Inho Kim , Kideok Do
We developed a self-attention-based spatiotemporal network called Beach that uses spatiotemporal representation learning for skillful prediction of shoreline changes multiple days ahead. The proposed model predicts the spatiotemporal position of the shoreline up to seven consecutive days in the future based on hydrodynamic forcing of ocean waves and tide data for the past 30 consecutive days. It is further divided into Beach-w/o IC and Beach-w/ IC depending on whether or not the beach state of the antecedent historical shoreline information is used as the initial condition. Beach-w/o IC, which does not incorporate this information, learns the sequential relationship between hydrodynamic forcing and shoreline to estimate overall trends of shoreline changes including seasonal oscillation from the point in time after model training, given only the ocean waves and tides. Beach-w/ IC does incorporate antecedent historical shoreline information to greatly enhance its predictive accuracy of shoreline progradation, retreat, and beach rotation for short-term time scales and for extreme storm events. The proposed model was applied to Tairua Beach, New Zealand, and it demonstrated superior predictive accuracy compared to previous methods and matched current understanding of accretion-dominated and oscillation-dominated shoreline changes.
我们开发了一种名为 alphaBeach 的基于自我注意力的时空网络，它利用时空表征学习来熟练预测未来多天的海岸线变化。所提出的模型可根据过去连续 30 天的海浪和潮汐数据，预测未来连续 7 天的海岸线时空位置。alphaBeach-w/o IC 不包含这一信息，它学习水动力作用力与海岸线之间的顺序关系，以估计海岸线变化的总体趋势，包括从模型训练后的时间点开始的季节性振荡。alphaBeach-w/ IC 结合了历史海岸线的先验信息，大大提高了对短期时间尺度和极端风暴事件的海岸线上升、后退和海滩旋转的预测精度。所提出的模型被应用于新西兰的 Tairua 海滩，与以前的方法相比，该模型显示出更高的预测准确性，并与当前对增生主导型和振荡主导型海岸线变化的理解相吻合。
{"title":"alphaBeach: Self-attention-based spatiotemporal network for skillful prediction of shoreline changes multiple days ahead","authors":"Jinah Kim , Taekyung Kim , Miyoung Yun , Inho Kim , Kideok Do","doi":"10.1016/j.apor.2024.104292","DOIUrl":"10.1016/j.apor.2024.104292","url":null,"abstract":"<div><div>We developed a self-attention-based spatiotemporal network called <span><math><mrow><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi></mrow></math></span>Beach that uses spatiotemporal representation learning for skillful prediction of shoreline changes multiple days ahead. The proposed model predicts the spatiotemporal position of the shoreline up to seven consecutive days in the future based on hydrodynamic forcing of ocean waves and tide data for the past 30 consecutive days. It is further divided into <span><math><mrow><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi></mrow></math></span>Beach-w/o<!--> <!-->IC and <span><math><mrow><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi></mrow></math></span>Beach-w/<!--> <!-->IC depending on whether or not the beach state of the antecedent historical shoreline information is used as the initial condition. <span><math><mrow><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi></mrow></math></span>Beach-w/o<!--> <!-->IC, which does not incorporate this information, learns the sequential relationship between hydrodynamic forcing and shoreline to estimate overall trends of shoreline changes including seasonal oscillation from the point in time after model training, given only the ocean waves and tides. <span><math><mrow><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi></mrow></math></span>Beach-w/<!--> <!-->IC does incorporate antecedent historical shoreline information to greatly enhance its predictive accuracy of shoreline progradation, retreat, and beach rotation for short-term time scales and for extreme storm events. The proposed model was applied to Tairua Beach, New Zealand, and it demonstrated superior predictive accuracy compared to previous methods and matched current understanding of accretion-dominated and oscillation-dominated shoreline changes.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104292"},"PeriodicalIF":4.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659263","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.apor.2024.104303
Xinfeng Zhai , Hongna Zhang , Suming Wang , Haotian Cheng , Kaiting Wang , Yan Wang , Xiaobin Li , Wenhua Zhang , Fengchen Li
Underwater vehicles consume much energy to overcome flow resistance; therefore, reducing drag is essential to enhancing its performance. This paper proposes a drag reduction method for underwater vehicles by injecting drag-reducing agents into the turbulent boundary layer of the underwater vehicles and experimentally evaluates its performance based on the scaled suboff model. To this end, the unique injection structure and location are carefully designed to ensure the adherence of the drag-reducing solution on the wall. The polyethyleneoxide (PEO) and ceytltrimethyl ammonium chloride (CTAC) solutions are chosen as the drag-reducing agents. The effects of concentrations, flow rates, and mainstream Reynolds numbers (Re) on the drag reduction performance are investigated by measuring the total drag resistance of the scaled suboff model under different conditions. The results demonstrate that this heterogeneous drag-reducing solution injection strategy performs well in terms of drag reduction for the suboff model. The specially designed injection structure can uniformly distribute the drag-reducing solution to the near-wall region of the suboff model. Under certain conditions, both PEO and CTAC solutions can significantly reduce the total drag resistance and have an optimal concentration at different Re. At their optimal concentrations, the drag reduction of the total resistance can achieve about 59.38% and 48.31% for PEO and CTAC solutions, respectively, at Re = 2.7 × 104. However, with the current design, the drag reduction decreases with the increase of Re due to the difficulty of the drag-reducing agent wrapping around the suboff model effectively. Further work is still necessary to improve the design and the location of the injection structure so that it can adapt to high-Re cases.
水下航行器需要消耗大量能量来克服流动阻力，因此减少阻力对提高其性能至关重要。本文提出了一种通过向水下航行器的湍流边界层注入减阻剂来减少水下航行器阻力的方法，并基于缩放子模型对其性能进行了实验评估。为此，我们精心设计了独特的注入结构和位置，以确保减阻溶液附着在壁面上。我们选择了聚环氧乙烷（PEO）和十六烷基三甲基氯化铵（CTAC）溶液作为减阻剂。通过测量按比例缩小的 suboff 模型在不同条件下的总阻力，研究了浓度、流速和主流雷诺数 (Re) 对减阻性能的影响。结果表明，这种异质减阻溶液注入策略对 suboff 模型的减阻效果良好。特殊设计的注入结构可以将减阻溶液均匀地分布到 suboff 模型的近壁区域。在一定条件下，PEO 和 CTAC 溶液都能显著降低总阻力，并在不同的 Re 值下具有最佳浓度。在 Re = 2.7 × 104 时，PEO 和 CTAC 溶液的最佳浓度分别可使总阻力降低约 59.38% 和 48.31%。然而，在目前的设计中，由于减阻剂难以有效地包裹子模型，因此减阻效果随着 Re 的增加而降低。还需要进一步改进喷射结构的设计和位置，使其能够适应高 Re 的情况。
{"title":"Experimental study on the drag reduction of underwater vehicles by drag-reducing agents injection","authors":"Xinfeng Zhai , Hongna Zhang , Suming Wang , Haotian Cheng , Kaiting Wang , Yan Wang , Xiaobin Li , Wenhua Zhang , Fengchen Li","doi":"10.1016/j.apor.2024.104303","DOIUrl":"10.1016/j.apor.2024.104303","url":null,"abstract":"<div><div>Underwater vehicles consume much energy to overcome flow resistance; therefore, reducing drag is essential to enhancing its performance. This paper proposes a drag reduction method for underwater vehicles by injecting drag-reducing agents into the turbulent boundary layer of the underwater vehicles and experimentally evaluates its performance based on the scaled suboff model. To this end, the unique injection structure and location are carefully designed to ensure the adherence of the drag-reducing solution on the wall. The polyethyleneoxide (PEO) and ceytltrimethyl ammonium chloride (CTAC) solutions are chosen as the drag-reducing agents. The effects of concentrations, flow rates, and mainstream Reynolds numbers (<em>Re</em>) on the drag reduction performance are investigated by measuring the total drag resistance of the scaled suboff model under different conditions. The results demonstrate that this heterogeneous drag-reducing solution injection strategy performs well in terms of drag reduction for the suboff model. The specially designed injection structure can uniformly distribute the drag-reducing solution to the near-wall region of the suboff model. Under certain conditions, both PEO and CTAC solutions can significantly reduce the total drag resistance and have an optimal concentration at different <em>Re</em>. At their optimal concentrations, the drag reduction of the total resistance can achieve about 59.38% and 48.31% for PEO and CTAC solutions, respectively, at <em>Re</em> = 2.7 × 10<sup>4</sup>. However, with the current design, the drag reduction decreases with the increase of <em>Re</em> due to the difficulty of the drag-reducing agent wrapping around the suboff model effectively. Further work is still necessary to improve the design and the location of the injection structure so that it can adapt to high-<em>Re</em> cases.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104303"},"PeriodicalIF":4.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659265","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}
Accurate and rapid prediction of water wave evolution is crucial for ensuring the safe and healthy operation of ocean and coastal engineering. Using hourly wave data from the coastal areas of the Hawaiian Islands from 2019 to 2021, this study developed an artificial intelligence model for rapidly predicting the spatiotemporal evolution of coastal waves by improving the STID algorithm. In the study, the SWAN wave model was used to generate an initial training dataset for driving Improved-STID algorithm, where the Improved-STID algorithm and SWAN model share the same unstructured computational grid with good adaptability to complex topography. The proposed Improved-STID algorithm takes into account the overall spatiotemporal correlations of wave evolution across different regions. The results show that on the basis of prediction efficiency on a par with the original STID, the Improved-STID can be more accurately applied to the spatiotemporal evolution process of coastal waves. The prediction errors in this study are: the RMSE of 0.23 m, MAE of 0.14 m, MAPE of 17.96 %, and the calculation time of the proposed AI model is only about 1.8 % of that of the SWAN wave model.
{"title":"An AI model for predicting the spatiotemporal evolution process of coastal waves by using the Improved-STID algorithm","authors":"Xinyu Huang , Jun Tang , Yongming Shen , Chenhao Zhang","doi":"10.1016/j.apor.2024.104299","DOIUrl":"10.1016/j.apor.2024.104299","url":null,"abstract":"<div><div>Accurate and rapid prediction of water wave evolution is crucial for ensuring the safe and healthy operation of ocean and coastal engineering. Using hourly wave data from the coastal areas of the Hawaiian Islands from 2019 to 2021, this study developed an artificial intelligence model for rapidly predicting the spatiotemporal evolution of coastal waves by improving the STID algorithm. In the study, the SWAN wave model was used to generate an initial training dataset for driving Improved-STID algorithm, where the Improved-STID algorithm and SWAN model share the same unstructured computational grid with good adaptability to complex topography. The proposed Improved-STID algorithm takes into account the overall spatiotemporal correlations of wave evolution across different regions. The results show that on the basis of prediction efficiency on a par with the original STID, the Improved-STID can be more accurately applied to the spatiotemporal evolution process of coastal waves. The prediction errors in this study are: the RMSE of 0.23 m, MAE of 0.14 m, MAPE of 17.96 %, and the calculation time of the proposed AI model is only about 1.8 % of that of the SWAN wave model.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104299"},"PeriodicalIF":4.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659165","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}
Storm surges, driven by Tropical Cyclones (TCs), pose a threat to the coastal areas of the Bay of Bengal (BoB), causing sediment transport and beach erosion. This study introduces a coupled hydrodynamic (TELEMAC-2D) -wave (TOMAWAC) -morphodynamic (GAIA) model to investigate morphodynamic changes during storm surges. The cyclonic wind is crucial for precisely predicting storm surges, wind waves, and morphodynamic bed evolution. Thus, this study introduced a modified parametric wind model to enhance wind field representation near and far from the cyclone center. The simulated storm surges and wind waves were validated against in-situ observations for TC Hudhud (2014) and TC Varadah (2016), and the simulated morphodynamic bed evolution was validated with field-measured data collected for TC Nivar (2020). Further, this study evaluates the performance of different bed load transport formulations for predicting morphodynamic bed evolution during TC Nivar (2020) under storm-induced currents and waves. Results indicate that the Engelund-Hansen model is most effective for currents alone, while the Bijker model excels for combined currents and waves along the open coast of BoB. The results also indicate that the incorporation of the effect of waves along with currents has enhanced the predictive capability of the coupled model framework.
{"title":"Investigation of morphodynamic response to the storm-induced currents and waves in the Bay of Bengal","authors":"V.G. Shashank , V. Sriram , Holger Schüttrumpf , S.A. Sannasiraj","doi":"10.1016/j.apor.2024.104285","DOIUrl":"10.1016/j.apor.2024.104285","url":null,"abstract":"<div><div>Storm surges, driven by Tropical Cyclones (TCs), pose a threat to the coastal areas of the Bay of Bengal (BoB), causing sediment transport and beach erosion. This study introduces a coupled hydrodynamic (TELEMAC-2D) -wave (TOMAWAC) -morphodynamic (GAIA) model to investigate morphodynamic changes during storm surges. The cyclonic wind is crucial for precisely predicting storm surges, wind waves, and morphodynamic bed evolution. Thus, this study introduced a modified parametric wind model to enhance wind field representation near and far from the cyclone center. The simulated storm surges and wind waves were validated against in-situ observations for TC Hudhud (2014) and TC Varadah (2016), and the simulated morphodynamic bed evolution was validated with field-measured data collected for TC Nivar (2020). Further, this study evaluates the performance of different bed load transport formulations for predicting morphodynamic bed evolution during TC Nivar (2020) under storm-induced currents and waves. Results indicate that the Engelund-Hansen model is most effective for currents alone, while the Bijker model excels for combined currents and waves along the open coast of BoB. The results also indicate that the incorporation of the effect of waves along with currents has enhanced the predictive capability of the coupled model framework.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104285"},"PeriodicalIF":4.3,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586403","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 : 2024-11-04DOI: 10.1016/j.apor.2024.104280
Valeria Mundaca-Moraga , Rodrigo Abarca-del-Rio
This study examines wave energy potential and generation capacity from extreme waves along South America's Pacific and Atlantic coasts. Utilizing the Regional Frequency Analysis (RFA) method and the WAVERYS wave reanalysis model, 27 homogeneous regions with distinct wave patterns were identified. There's a notable southward increase in median and average wave heights and energy. Unlike previous studies, this research emphasizes the significant role of extreme wave events, which contribute up to 33 % of the total energy—a critical factor often overlooked in regional energy assessments. In the Pacific, three main zones were delineated, with energy peaks reaching 120 kW/m south of 50°S, while the Atlantic identified two zones with energy values ranging from 10 kW/m to 30 kW/m. Zones between 10°S to 40°S in the Pacific and 30°S to 60°S in the Atlantic stand out as particularly promising for energy harvesting. A comprehensive statistical methodology enabled predictions of wave heights and energy for 50 and 100-year return periods, predominantly utilized generalized Pareto and Gumbel distributions. The study affirms the efficacy of the RFA in improving the understanding of wave dynamics and highlights the necessity of integrating extreme events in energy assessments. This research provides a foundation for advancing wave energy initiatives and coastal risk mitigation in South America.
{"title":"Wave Energy Potential and the Role of Extreme Events on South America's Coasts. A Regional Frequency Analysis","authors":"Valeria Mundaca-Moraga , Rodrigo Abarca-del-Rio","doi":"10.1016/j.apor.2024.104280","DOIUrl":"10.1016/j.apor.2024.104280","url":null,"abstract":"<div><div>This study examines wave energy potential and generation capacity from extreme waves along South America's Pacific and Atlantic coasts. Utilizing the Regional Frequency Analysis (RFA) method and the WAVERYS wave reanalysis model, 27 homogeneous regions with distinct wave patterns were identified. There's a notable southward increase in median and average wave heights and energy. Unlike previous studies, this research emphasizes the significant role of extreme wave events, which contribute up to 33 % of the total energy—a critical factor often overlooked in regional energy assessments. In the Pacific, three main zones were delineated, with energy peaks reaching 120 kW/m south of 50°S, while the Atlantic identified two zones with energy values ranging from 10 kW/m to 30 kW/m. Zones between 10°S to 40°S in the Pacific and 30°S to 60°S in the Atlantic stand out as particularly promising for energy harvesting. A comprehensive statistical methodology enabled predictions of wave heights and energy for 50 and 100-year return periods, predominantly utilized generalized Pareto and Gumbel distributions. The study affirms the efficacy of the RFA in improving the understanding of wave dynamics and highlights the necessity of integrating extreme events in energy assessments. This research provides a foundation for advancing wave energy initiatives and coastal risk mitigation in South America.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104280"},"PeriodicalIF":4.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142577971","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 : 2024-11-04DOI: 10.1016/j.apor.2024.104297
Liheng Tang , Chencong Liao , Guanlin Ye , Yuanxi Li , Diyang Zhu
Sandy seabed, prevalent near continental shelves, often contains fines that obviously affect their apparent behaviour. The variation in the physical properties of sands and fines, the difference between seismic and marine wave loads, and the challenges in obtaining accurate geotechnical parameters and undisturbed samples for analysis make it difficult to effectively evaluate the properties of sands with plastic fines in offshore engineering. To address this issue, a method for discriminating and re-sampling sands with plastic fines is suggested, along with a case study to assess the static and dynamic behaviours of such sands from an offshore site in the South China Sea. In this study, evaluation processes for detecting the presence of fines in sands and classifying them as plastic or non-plastic are first recommended to gain a better understanding of such sands. Then, a reconstitution approach of re-sampling for disturbed sand samples from site and compactness assessment guided by the optimum moisture content, is suggested to restore their in-situ characteristics, addressing the difficulty in obtaining undisturbed sand samples. Subsequently, the failure behavior and shear strain development under cyclic loading are analyzed via a cyclic contour diagram to evaluate their mechanical properties under marine environmental loads. The obtained contour diagrams can be further integrated into the constitutive model in subsequent research and used in finite element analysis to simplify the computation for marine foundation design. These results can provide valuable insights for improving understandings and engineering practices related to sandy seabed with plastic fines in offshore environments.
{"title":"Evaluation, sampling and testing methods for offshore disturbed sands with plastic fines: A case study","authors":"Liheng Tang , Chencong Liao , Guanlin Ye , Yuanxi Li , Diyang Zhu","doi":"10.1016/j.apor.2024.104297","DOIUrl":"10.1016/j.apor.2024.104297","url":null,"abstract":"<div><div>Sandy seabed, prevalent near continental shelves, often contains fines that obviously affect their apparent behaviour. The variation in the physical properties of sands and fines, the difference between seismic and marine wave loads, and the challenges in obtaining accurate geotechnical parameters and undisturbed samples for analysis make it difficult to effectively evaluate the properties of sands with plastic fines in offshore engineering. To address this issue, a method for discriminating and re-sampling sands with plastic fines is suggested, along with a case study to assess the static and dynamic behaviours of such sands from an offshore site in the South China Sea. In this study, evaluation processes for detecting the presence of fines in sands and classifying them as plastic or non-plastic are first recommended to gain a better understanding of such sands. Then, a reconstitution approach of re-sampling for disturbed sand samples from site and compactness assessment guided by the optimum moisture content, is suggested to restore their in-situ characteristics, addressing the difficulty in obtaining undisturbed sand samples. Subsequently, the failure behavior and shear strain development under cyclic loading are analyzed via a cyclic contour diagram to evaluate their mechanical properties under marine environmental loads. The obtained contour diagrams can be further integrated into the constitutive model in subsequent research and used in finite element analysis to simplify the computation for marine foundation design. These results can provide valuable insights for improving understandings and engineering practices related to sandy seabed with plastic fines in offshore environments.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104297"},"PeriodicalIF":4.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142577972","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 : 2024-11-04DOI: 10.1016/j.apor.2024.104301
Atefeh Neisi , Hassan Ghassemi , Mehdi Iranmanesh
The design of mooring lines for floating platforms is an essential task to guarantee structure survivability and its components under different metocean conditions. This paper focuses on the application and comparison of the MSM-BMW system across various types of semisubmersible platforms, including the OC4-DeepCwind, the braceless semi-submersible (BSS) with three catenary mooring lines, and the drilling rig GVA 4000 with eight mooring lines. The performance of the BMW mooring system for these three platforms is compared under operational and survival conditions. The hybrid mooring concept is a multi-segment mooring (MSM) arrangement of the catenary and taut, including single buoy and multi-clump weight (BMW), generally named MSM-BMW. Hydrodynamic responses and mooring forces are compared between original and hybrid systems under regular and irregular wave conditions. The dynamic response of the platform is performed utilizing both Morrison theory and three-dimensional radiation/diffraction theory based on the boundary element method (BEM) in ANSYS-AQWA software. The results show that using BMW on the three floating platforms significantly reduces platform motion at low frequencies, with minimal effect on wave-frequency resonance. However, the BMW system increases mooring force at wave frequency, while having a smaller effect at low frequencies. The effectiveness of the BMW system varies across platforms and motion types. The BSS platform shows significant improvement in surge motion, while the GVA platform has the smallest ratio in heave motion. Additionally, the BSS platform demonstrates the least response in pitch motion.
浮式平台的系泊缆线设计是保证结构及其部件在不同海洋条件下的生存能力的一项重要任务。本文重点介绍了 MSM-BMW 系统在不同类型半潜式平台上的应用和比较，包括 OC4-DeepCwind、配备三根导管缆绳的无支架半潜式平台（BSS）和配备八根缆绳的 GVA 4000 钻井平台。对这三个平台的 BMW 系泊系统在操作和生存条件下的性能进行了比较。混合系泊概念是一种多段系泊（MSM），包括单浮标和多块重物（BMW），一般命名为 MSM-BMW。比较了原始系统和混合系统在规则和不规则波浪条件下的水动力响应和系泊力。在 ANSYS-AQWA 软件中，利用基于边界元法（BEM）的莫里森理论和三维辐射/衍射理论对平台的动态响应进行了研究。结果表明，在三个浮动平台上使用 BMW 系统可显著减少低频时的平台运动，对波频共振的影响微乎其微。然而，BMW 系统增加了波频下的系泊力，而对低频的影响较小。BMW 系统的效果因平台和运动类型而异。BSS 平台在浪涌运动方面有明显改善，而 GVA 平台在波浪运动方面的比率最小。此外，BSS 平台对俯仰运动的响应最小。
{"title":"Dynamic response of three different floating platform (OC4, BSS, GVA) using multi-segment mooring system","authors":"Atefeh Neisi , Hassan Ghassemi , Mehdi Iranmanesh","doi":"10.1016/j.apor.2024.104301","DOIUrl":"10.1016/j.apor.2024.104301","url":null,"abstract":"<div><div>The design of mooring lines for floating platforms is an essential task to guarantee structure survivability and its components under different metocean conditions. This paper focuses on the application and comparison of the MSM-BMW system across various types of semisubmersible platforms, including the OC4-DeepCwind, the braceless semi-submersible (BSS) with three catenary mooring lines, and the drilling rig GVA 4000 with eight mooring lines. The performance of the BMW mooring system for these three platforms is compared under operational and survival conditions. The hybrid mooring concept is a multi-segment mooring (MSM) arrangement of the catenary and taut, including single buoy and multi-clump weight (BMW), generally named MSM-BMW. Hydrodynamic responses and mooring forces are compared between original and hybrid systems under regular and irregular wave conditions. The dynamic response of the platform is performed utilizing both Morrison theory and three-dimensional radiation/diffraction theory based on the boundary element method (BEM) in ANSYS-AQWA software. The results show that using BMW on the three floating platforms significantly reduces platform motion at low frequencies, with minimal effect on wave-frequency resonance. However, the BMW system increases mooring force at wave frequency, while having a smaller effect at low frequencies. The effectiveness of the BMW system varies across platforms and motion types. The BSS platform shows significant improvement in surge motion, while the GVA platform has the smallest ratio in heave motion. Additionally, the BSS platform demonstrates the least response in pitch motion.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104301"},"PeriodicalIF":4.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142577973","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 : 2024-11-01DOI: 10.1016/j.apor.2024.104294
Qiang Xi , Zhuojia Fu , Mi-An Xue , Junpu Li , Elena Atroshchenko , Jinhai Zheng
Understanding underwater acoustic radiation and propagation induced by structural vibration in the ocean environment involves analyzing the interaction between the ocean acoustic field and the structure. For this reason, this paper proposes a novel hybrid scheme integrating the finite element method (FEM), singular boundary method (SBM) and Burton-Miller (BM) technique. The three-dimensional and axisymmetric calculation formulations of the hybrid scheme are presented. By leveraging the respective strengths, the FEM simulates structural free vibrations, the SBM analyzes underwater acoustics in various ocean environments, and the BM technique resolves irregular frequency issues. The accuracy and feasibility of the hybrid FEM-BMSBM are confirmed by comparisons with experimental and other numerical results. The numerical findings demonstrate that the hybrid FEM-BMSBM alleviates the high computational cost of the traditional FEM and the ill-posed problem of the wave superposition method (WSM), and successfully mitigates irregular frequency phenomena of underwater acoustic simulations in various ocean environments. Additionally, the influence of the ocean surface and sediment on the underwater sound field is studied. Numerical study shows that the reflection effects of the ocean surface and sediment cause fluctuations in the underwater sound pressure level curve, and the number of side lobes of the sound pressure level curve increases with the increase of the excitation frequency.
{"title":"Numerical study of underwater acoustic radiation and propagation induced by structural vibration in ocean environments using FEM-BMSBM","authors":"Qiang Xi , Zhuojia Fu , Mi-An Xue , Junpu Li , Elena Atroshchenko , Jinhai Zheng","doi":"10.1016/j.apor.2024.104294","DOIUrl":"10.1016/j.apor.2024.104294","url":null,"abstract":"<div><div>Understanding underwater acoustic radiation and propagation induced by structural vibration in the ocean environment involves analyzing the interaction between the ocean acoustic field and the structure. For this reason, this paper proposes a novel hybrid scheme integrating the finite element method (FEM), singular boundary method (SBM) and Burton-Miller (BM) technique. The three-dimensional and axisymmetric calculation formulations of the hybrid scheme are presented. By leveraging the respective strengths, the FEM simulates structural free vibrations, the SBM analyzes underwater acoustics in various ocean environments, and the BM technique resolves irregular frequency issues. The accuracy and feasibility of the hybrid FEM-BMSBM are confirmed by comparisons with experimental and other numerical results. The numerical findings demonstrate that the hybrid FEM-BMSBM alleviates the high computational cost of the traditional FEM and the ill-posed problem of the wave superposition method (WSM), and successfully mitigates irregular frequency phenomena of underwater acoustic simulations in various ocean environments. Additionally, the influence of the ocean surface and sediment on the underwater sound field is studied. Numerical study shows that the reflection effects of the ocean surface and sediment cause fluctuations in the underwater sound pressure level curve, and the number of side lobes of the sound pressure level curve increases with the increase of the excitation frequency.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104294"},"PeriodicalIF":4.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572013","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 : 2024-11-01DOI: 10.1016/j.apor.2024.104298
Humberto Carro , Andrés Figuero , José Sande , Alberto Alvarellos , Raquel Costas , Enrique Peña
The moored ship motions can cause problems for the efficiency of the operation, and for the people and equipment involved. Therefore, being able to predict movements and anticipate possible risk situations is of great interest to operators and the port community. This work presents a methodology applying different machine learning techniques that has allowed positive results to be obtained for this objective, with particular emphasis on the highest values (outliers), which are usually associated with problematic situations. The field campaigns carried out allowed 77 different vessels to be monitored in the outer port of A Coruña (Spain). The techniques used were gradient boosting (GBM), a neural network (DNN), a quantile regression (qReg) and several models generated by stacking (GBM*). The results indicate a lower root mean square error (RMSE) with the use of the latter technique (the validation on the swell is 0.13 m, while the DNN is twice as high), and a better performance on most motions in the outlier subset than those obtained with the individual models (the validation on the outlier subset for the pitch gives an RMSE of 0.12° and 0.2 for the GBM). Finally, the results show that this methodology can be extrapolated to other ports.
{"title":"Estimation of moored ship motions using a combination of machine learning techniques","authors":"Humberto Carro , Andrés Figuero , José Sande , Alberto Alvarellos , Raquel Costas , Enrique Peña","doi":"10.1016/j.apor.2024.104298","DOIUrl":"10.1016/j.apor.2024.104298","url":null,"abstract":"<div><div>The moored ship motions can cause problems for the efficiency of the operation, and for the people and equipment involved. Therefore, being able to predict movements and anticipate possible risk situations is of great interest to operators and the port community. This work presents a methodology applying different machine learning techniques that has allowed positive results to be obtained for this objective, with particular emphasis on the highest values (outliers), which are usually associated with problematic situations. The field campaigns carried out allowed 77 different vessels to be monitored in the outer port of A Coruña (Spain). The techniques used were gradient boosting (GBM), a neural network (DNN), a quantile regression (qReg) and several models generated by stacking (GBM*). The results indicate a lower root mean square error (RMSE) with the use of the latter technique (the validation on the swell is 0.13 m, while the DNN is twice as high), and a better performance on most motions in the outlier subset than those obtained with the individual models (the validation on the outlier subset for the pitch gives an RMSE of 0.12° and 0.2 for the GBM). Finally, the results show that this methodology can be extrapolated to other ports.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"153 ","pages":"Article 104298"},"PeriodicalIF":4.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572014","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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