Ocean Engineering最新文献

{"title":"Offshore turbidity currents forecasting (part I): Integrating deep learning and computational fluid dynamics","authors":"F. Fazel Mojtahedi,&nbsp;N. Yousefpour,&nbsp;S.H. Chow,&nbsp;M. Cassidy","doi":"10.1016/j.oceaneng.2025.121360","DOIUrl":"10.1016/j.oceaneng.2025.121360","url":null,"abstract":"<div><div>This study introduces a novel methodology for real-time forecasting of turbidity currents, a significant geohazard to offshore infrastructures such as pipelines and submarine telecommunication networks. Numerical modeling, deeap learning (DL) techniques, and field measurements were incorporated to provide accurate predictions of upcoming turbidity current events. A forecasting model was developed using a combination of two DL methods, Convolutional Neural Networks (CNNs) and Long Short-Term Memory networks (LSTMs). This combination is helpful in capturing both spatial features and temporal sequences in the data, making it well-suited for predicting the movement and behavior of turbidity currents. The DL models (CNN-LSTM) were initially trained using synthetic data from Computational Fluid Dynamics (CFD) analyses, and then real field dataset from an Acoustic Doppler Current Profiler (ADCP) in the Congo Canyon, West Africa. The CFD analysis incorporated a turbulence model known as the renormalization group k-epsilon model to enhance accuracy, and it was validated with an experimental dataset. To fine-tune the DL models, Bayesian hyperparameter tuning was employed, a method that systematically adjusts the settings of the model to enhance performance. Also, employing transfer learning, a technique that transfers knowledge from simulated data to actual field data, reduced prediction errors by 50 %. The pretrained models were fine-tuned and the impacts of the key hyperparameters such as input-label width ratio, forecast window length, and data resolution were investigated. After fine-tuning, the optimized models achieved prediction accuracies with less than 10 % error, utilizing data sampled every 480 s across a forecasting window of 40 h. Overall, the proposed DL methodology presents a promising basis for an AI-based early warning system against turbidity current hazards for offshore and marine infrastructures.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121360"},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892000","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}

{"title":"Analysis of mechanical behavior of deep-sea unbonded flexible risers under localized corrosion conditions","authors":"Chao Li ,&nbsp;Meng Li ,&nbsp;Hu Liu ,&nbsp;Rongqian Ruan ,&nbsp;Fusen Peng ,&nbsp;Yanlian Du ,&nbsp;Yijun Shen ,&nbsp;Yongqi Ma","doi":"10.1016/j.oceaneng.2025.121345","DOIUrl":"10.1016/j.oceaneng.2025.121345","url":null,"abstract":"<div><div>Unbonded flexible risers (UFRs) used in the intermediate transportation in seabed mining are prone to corrosion in seawater during long-term operation. In this study, 8-layer UFRs were equivalent to 5-layer UFRs, and the constitutive equations for the 5-layer UFRs were derived using the principle of stiffness equivalence. The length and width of the outer tensile armour layer and the effect of composite corrosion on the stiffness of the UFRs at different corrosion depths were investigated separately. Additionally, the displacement of the helical steel strip when buckling occurred and when it reached the yield limit under axial pressure owing to composite corrosion are discussed herein. The results indicated that when the corrosion depth was 1 mm, the stiffness reductions caused by the corrosion length were 3.92 %, 6.26 %, and 4.2 % for tensile, clockwise torsion, and counterclockwise torsion, respectively. The reductions caused by the corrosion width were 4.04 %, 5.41 %, and 3.29 %, with composite corrosion stiffness reductions of 48.21 %, 5.99 %, and 33.73 %, respectively. The buckling analysis of the UFRs under axial compression demonstrated that buckling failure occurred earlier in the corroded regions. When the corrosion depth reached 1 mm, the spiral steel strip exhibited signs of folding.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121345"},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891993","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}

{"title":"Experimental investigation of flow characteristics around triangular cylinders in various angular orientations in a tandem configuration","authors":"Renata Gnatowska,&nbsp;Agnieszka Kocoń,&nbsp;Karolina Gajewska","doi":"10.1016/j.oceaneng.2025.121356","DOIUrl":"10.1016/j.oceaneng.2025.121356","url":null,"abstract":"<div><div>This study investigates the flow around two bluff bodies (BBs) arranged in tandem. The upstream triangular cylinder is tested at three apex and rotation angles, while a square cylinder serves as the downstream body, positioned at varying gap spacings (<span><math><mi>G</mi></math></span>). The study also includes measurements for single triangular cylinders to demonstrate how the second object alters the flow. The results reveal that both the apex angle and gap spacing have significant effects on the flow characteristics. As the gap decreases from <span><math><mrow><mn>4</mn><mi>D</mi></mrow></math></span> to <span><math><mrow><mn>2</mn><mi>D</mi></mrow></math></span>, the wake structure becomes more complex, with stronger cross-stream velocities and vortical structures near the downstream cylinder. The wake becomes asymmetric in the perpendicular (A90) configuration, and larger gaps (<span><math><mrow><mi>G</mi><mo>=</mo><mn>4</mn><mi>D</mi></mrow></math></span>) result in smaller vortices. Gap spacing also affects turbulent kinetic energy, with smaller gaps (<span><math><mrow><mi>G</mi><mo>=</mo><mn>2</mn><mi>D</mi></mrow></math></span>) leading to more organized vortex structures, while larger gaps (<span><math><mrow><mi>G</mi><mo>=</mo><mn>4</mn><mi>D</mi></mrow></math></span>) amplify the influence of the apex angle on wake dynamics. These findings build on the work of Niegodajew et al. (2024a), enhancing the understanding of tandem bluff body interactions by highlighting the critical roles of the apex angle, orientation, and gap spacing in vortex shedding and turbulence. These results are particularly relevant for ocean engineering, aiding in the design and analysis of offshore structures like subsea pipelines, risers, and breakwaters by informing assessments of hydrodynamic loading, vortex-induced vibrations, and stability.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121356"},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891995","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}

{"title":"A self-adaptive particle swarm speed optimization method for unmanned sailboats considering roll constraint","authors":"Fen Liu ,&nbsp;Liufeng Qiao ,&nbsp;Hongqiang Sang ,&nbsp;Xiujun Sun ,&nbsp;Fang Huang","doi":"10.1016/j.oceaneng.2025.121365","DOIUrl":"10.1016/j.oceaneng.2025.121365","url":null,"abstract":"<div><div>The unmanned sailboat is increasingly used for marine data collection and environmental monitoring. However, it faces significant challenges in optimizing speed under complex sea conditions while ensuring navigation safety. Notably, large roll angle during navigation can greatly increase the risk of capsizing. To address this problem, a 6-degree-of-freedom dynamic model of the unmanned sailboat is established, and a self-adaptive particle swarm speed optimization algorithm with roll constraint is proposed. This algorithm is used to optimize the sail angle to achieve maximum speed while minimizing roll angle. It adopts dynamic-objective constraint-handling method to convert the single-objective constraint into a bi-objective optimization problem, and maps the roll angle constraint onto the input parameters of the wing sail. The optimized sail angle with maximum output speed and minimum roll angle is applied to the unmanned sailboat to form a feedback control. The sea trial has been performed and the results demonstrate the superiority, effectiveness, and robustness of the proposed algorithm.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121365"},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891999","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}

{"title":"Anomaly detection method for ship trajectory based on stay region mining","authors":"Dongsheng Xu ,&nbsp;Jiaxuan Yang ,&nbsp;Ken Sinkou Qin ,&nbsp;Yuhao Qi ,&nbsp;Ziyao Zhou","doi":"10.1016/j.oceaneng.2025.121364","DOIUrl":"10.1016/j.oceaneng.2025.121364","url":null,"abstract":"<div><div>To address the issue of detecting anomalous sub-trajectories, such as circling and lane-changing behavior, an anomaly detection method for ship trajectory based on stay region mining (TADS) is proposed. Firstly, stay regions are mined using kernel density analysis based on stay points, which are obtained by combining heading deviation and heading zones. Secondly, sub-trajectories are generated by dividing ship trajectories based on stay regions, forming independent sub-trajectory sets both within and between different regions. And then, the similarity matrix between sub-trajectory features within each sub-trajectory set is constructed using edit distance. Finally, an adaptive hierarchical clustering algorithm is applied to detect anomalous sub-trajectories based on the similarity matrix. The AIS data from Lake Superior and Lake Huron are used as experimental samples to test TADS. The results indicate that TADS identified 11 and 7 stay regions in Lake Superior and Lake Huron, respectively, with an average trajectory anomaly detection accuracy of 91.27 <span><math><mo>%</mo></math></span>, a precision of 94.65 <span><math><mo>%</mo></math></span>, a recall of 94.72 <span><math><mo>%</mo></math></span>, and an <em>F</em>-measure of 94.67 <span><math><mo>%</mo></math></span>. Compared to similar methods, TADS exhibits better performance in detecting anomalous trajectories.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121364"},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891996","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}

{"title":"Dynamic analysis of steel catenary riser with hydrodynamic dampers conveying internal slug flow","authors":"Shengbo Xu ,&nbsp;Yang Yu ,&nbsp;Jinfang Hou ,&nbsp;Zhichao Dong ,&nbsp;Chaoyang Wang ,&nbsp;Xin Liu","doi":"10.1016/j.oceaneng.2025.121326","DOIUrl":"10.1016/j.oceaneng.2025.121326","url":null,"abstract":"<div><div>The steel catenary riser (SCR) employed in ultradeep-water petroleum exploitation is constrained by excessive stress and top tension. The application of discretely arranged low-density coatings, forming an SCR with hydrodynamic dampers (SCR-HD), has been demonstrated to effectively address these problems without significantly extending the length of the riser. In this study, the performance of an SCR-HD was systematically evaluated and compared with that of a typical SCR using the vector form intrinsic finite element method. Dynamic simulations of both risers were conducted under different combinations of internal flows and top-end excitations. The vibrations, internal forces, and fatigue damages of the SCR and SCR-HD were analyzed to determine the effects of slug flow and hydrodynamic dampers. The simulation results indicated that attaching hydrodynamic dampers reduced the tension and stress of the riser and decreased fatigue damage at the hang-off point. However, fatigue damage within the lower catenary region and touchdown zone of the SCR-HD became severe. The top-end excitation contributed the most to the fatigue damage of the risers, and the slug flow induced high-frequency vibration components and amplified internal forces.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121326"},"PeriodicalIF":4.6,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143881574","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}

{"title":"Active countermeasures against landslide impulse wave hazards: Energy dissipation mechanism of the new weir- pool type wave-resistant structure","authors":"Qiuwang Li ,&nbsp;Bolin Huang ,&nbsp;Shulou Cheng ,&nbsp;Guowei Li ,&nbsp;Jie Zhang ,&nbsp;Pengcheng Li ,&nbsp;Yunfei Chen","doi":"10.1016/j.oceaneng.2025.121373","DOIUrl":"10.1016/j.oceaneng.2025.121373","url":null,"abstract":"<div><div>Breakwaters or seawalls designed to mitigate landslide-induced impulse wave are rare but serve as the last barrier protecting reservoir shore settlements from impulse wave attacks. Further research on low-height breakwater and seawall designs compatible with human habitats is crucial. This study proposes a novel weir-pool type wave-resistant structure based on the energy dissipation principles observed in natural cascading water flows within stepped pools. Through a series of two-dimensional flume experiments, the energy dissipation mechanisms and wave resistance effects of both single and multi-level weir-pool structures were investigated. The experimental results demonstrate that the Weir-pool type wave-resistant structure exhibits significantly enhanced wave dissipation performance compared to conventional vertical seawalls. Within the tested wave height range, the improvement in energy dissipation efficiency reached 14.99 %–76.81 %. The impact location of the impulse wave plays a decisive role in the wave dissipation efficiency of the weir-pool type wave-resistant structure. When the impulse wave strikes before the junction point between the pool base and the rear wall, overtopping is effectively prevented; beyond this point, the efficiency ranges between 65 % and 90 %. Through systematic analysis of the structural characteristics and hydrodynamic response, incident wave height, pool depth, and pool width were identified as the key design parameters. By integrating these findings with hydraulic jump theory, a design methodology for single-stage Weir-pool type wave-resistant structures was developed. The research findings provide valuable references for landslide-induced impulse wave prevention and control in reservoir areas, as well as practical engineering design guidelines, thereby significantly enhancing the safety of reservoir shoreline communities.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121373"},"PeriodicalIF":4.6,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143881577","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}

{"title":"Effect of wave height on seismic fragility of subsea tunnels in sandy seabed","authors":"Ling-Yu Xu ,&nbsp;Ju-Ping Xi ,&nbsp;Jia-Wei Jiang ,&nbsp;Fei Cai ,&nbsp;Yong-Yi Li ,&nbsp;Guo-Xing Chen","doi":"10.1016/j.oceaneng.2025.121359","DOIUrl":"10.1016/j.oceaneng.2025.121359","url":null,"abstract":"<div><div>The combined of earthquakes and waves cause significant challenges to the subsea shield tunnels in liquefiable seabed. Present seismic fragility analyses of the subsea tunnels have largely overlooked the coupling effect of wave action and seabed liquefaction. This study addresses this gap by employing a numerical model that integrates Biot theory with a modified generalized plasticity model. The effect of the wave height on the tunnel fragility is investigated through the incremental dynamic analysis, which adopts 18 seismic records scaled to 10 intensity levels. The damage probability of tunnels is governed by the interplay between seismic intensity and wave height. Particularly, a rise in wave height leads to greater liquefaction depth and higher bending moment of tunnels, particularly elevating the damage probability of tunnels under high seismic intensity conditions. The finding highlights the combined influence of wave action and seabed liquefaction on seismic behavior of the tunnel – seabed system and provide novel insights for improving the resilience of subsea tunnels in liquefiable seabed prone to multi-hazard interactions.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121359"},"PeriodicalIF":4.6,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143881572","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}

{"title":"Dynamics modeling and impact resistance study of the marine gas turbine isolation system","authors":"Yanfeng Zhou ,&nbsp;Weifang Chen ,&nbsp;Dan Wang ,&nbsp;Rupeng Zhu","doi":"10.1016/j.oceaneng.2025.121225","DOIUrl":"10.1016/j.oceaneng.2025.121225","url":null,"abstract":"<div><div>The isolation system, which protects the gas turbine by isolating the impact from the ship's hull when the ship is impacted, consists of a steel frame and isolation elements. A rate-dependent generalized Prandtl-Ishlinskii model is proposed and the mechanical models of the isolation elements are developed, which are verified by impact tests and found to have a maximum error of 3.05 % in relative displacement and 9.75 % in acceleration. The steel frame is discretized into multiple Timoshenko beam cells, and a stiffness matrix establishment method for spatial rigid-flexible coupling unit is proposed to establish the dynamics model of the isolation system. The maximum error in the natural frequency of the steel frame is found to be 8.44 % by comparing with the simulation results, and the maximum error in the natural frequency of the steel frame-gas turbine system is found to be −10.62 %. The impact dynamics calculations are completed based on the pseudo-force method, and the influence of the isolation elements arrangement on the isolation performance is analyzed in conjunction with the energy transfer between modes. The isolation system has the highest energy share for the 7th, 8th, and 11th order modes, and it does affect the energy share of each order mode when changing the number, position, and spacing of the isolation elements.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121225"},"PeriodicalIF":4.6,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143881575","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}

{"title":"An experimental study on pedestrian walking speed considering combined effect of heeling and trim","authors":"Yong Jiang,&nbsp;Zihang Li,&nbsp;Yurou Mao,&nbsp;Boxuan Wang,&nbsp;Dawei Zhang","doi":"10.1016/j.oceaneng.2025.121300","DOIUrl":"10.1016/j.oceaneng.2025.121300","url":null,"abstract":"<div><div>This study investigates the impact of inclined conditions on pedestrian walking speeds, focusing on both individual and crowd walking modes. A total of fifteen different combinations of heeling and trim angles were simulated to conduct a comprehensive evacuation experiment. The heeling angles <span><math><mi>α</mi></math></span> considered were <span><math><msup><mn>0</mn><mo>∘</mo></msup></math></span>, <span><math><msup><mn>5</mn><mo>∘</mo></msup></math></span>, and <span><math><msup><mn>10</mn><mo>∘</mo></msup></math></span>, while the trim angles <span><math><mi>β</mi></math></span> were <span><math><msup><mn>0</mn><mo>∘</mo></msup></math></span>, <span><math><mrow><mo>±</mo><msup><mn>10</mn><mo>∘</mo></msup></mrow></math></span>, and <span><math><mrow><mo>±</mo><msup><mn>15</mn><mo>∘</mo></msup></mrow></math></span>. Results indicate that average pedestrian walking speeds in both individual and crowd walking modes follow a similar trend as the trim angle <span><math><mi>β</mi></math></span> varies from <span><math><mrow><mo>−</mo><msup><mn>15</mn><mo>∘</mo></msup></mrow></math></span> to <span><math><msup><mn>15</mn><mo>∘</mo></msup></math></span>, with the heeling angle <span><math><mi>α</mi></math></span> at <span><math><msup><mn>0</mn><mo>∘</mo></msup></math></span>, <span><math><msup><mn>5</mn><mo>∘</mo></msup></math></span>, or <span><math><msup><mn>10</mn><mo>∘</mo></msup></math></span>. Under combined trim and heeling conditions, the average pedestrian speed in crowd walking mode is more sensitive to changes in heeling inclination compared to individual walking mode. Furthermore, under the same inclination angles, pedestrian walking speeds in crowd walking mode exhibit a more concentrated distribution compared to those in individual walking mode. Moreover, analysis of the spatiotemporal distribution of instantaneous velocities reveals that the trends in walking speeds during crowd walking mode in inclined scenarios follow a similar pattern to those observed in individual walking mode. The results will provide fundamental guidance to the practical human evacuation from passenger ships.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"331 ","pages":"Article 121300"},"PeriodicalIF":4.6,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143881643","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}