Ocean Engineering最新文献

{"title":"Real-time prediction of structural responses in deep-water jacket platforms using Ada-STLNet: A comprehensive analysis with prototype monitoring data","authors":"Aming Yue ,&nbsp;Shuang Gao ,&nbsp;Congzhi Cheng ,&nbsp;Lei Zhou ,&nbsp;Lingfei Dai ,&nbsp;Dongxu Zhu ,&nbsp;Lei Liu ,&nbsp;Wenhua Wu","doi":"10.1016/j.oceaneng.2024.119888","DOIUrl":"10.1016/j.oceaneng.2024.119888","url":null,"abstract":"<div><div>Real-time prediction of the mechanical behaviors based on prototype monitoring data is crucial for ensuring the integrity and safety of deep-water jacket platforms. As complex nonlinear systems, these platforms’ response exhibit varying temporal trends, dynamic spatial correlations, and load dependencies. This makes accurate prediction of future axial force and bending moment responses a significant challenge. In this paper, a novel deep learning method called Adaptive Spatio-Temporal Load Network (Ada-STLNet) is proposed aiming to address the issue of multi-node axial force and bending moment response prediction of deep-water jacket platform. Our model utilizes an enhanced graph convolution (EGCN) and self-attention mechanism for efficient spatial correlation modeling in multi-node response, LSTM for long sequence temporal feature capture. It integrates spatial and temporal, along with load-aware modules to capture intricate patterns in structural responses. Additionally, a multi-gated coupling mechanism with two independent gating modules is designed to adaptively represent the complex dependencies of structural responses, ensuring model stability and robustness. Extensive experiments conducted on prototype structural monitoring data from a deep-water jacket platform in the South China Sea demonstrate that Ada-STLNet outperforms six traditional models, including HA, SVR, KNN, MLP, LSTM, and GRU, across various prediction steps. The proposed model exhibits superior accuracy, particularly in short-term predictions, achieving up to 62.80% improvement in MAE and 48.11% in RMSE for axial force predictions compared to the second-best model. Ablation studies confirm the effectiveness of each component within Ada-STLNet. This research highlights the potential of Ada-STLNet for reliable and accurate prediction of structural responses, contributing significantly to the field of marine engineering.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119888"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722226","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":"Velocity field measurements under Very Large Floating Structures interacting with surface waves","authors":"Esra Uksul ,&nbsp;Angeliki Laskari ,&nbsp;Sebastian Schreier ,&nbsp;Christian Poelma","doi":"10.1016/j.oceaneng.2024.119759","DOIUrl":"10.1016/j.oceaneng.2024.119759","url":null,"abstract":"<div><div>Increasing utilization of ocean space and a global push for renewable energy solutions has spurred interest in wave behavior around Very Large Floating Structures, like floating photovoltaic (PV) systems. Flexible PV modules may be more suitable for the varying wave conditions found in offshore environments. However, while viscoelastic models are commonly used for wave prediction, they show notable discrepancies with experiments, likely due to untested assumptions of inviscid flow. This experimental study aims to fill that gap by investigating both the wave characteristics and velocity fields underneath flexible and rigid structures using simultaneous Particle Image Velocimetry (PIV) and wave elevation measurements. Wave attenuation is observed for short wavelengths over the flexible structure length. The 2nd order Stokes wave theory provides a good approximation of the wave-induced horizontal velocity profiles under the flexible structure but underestimates the velocities under the rigid one which further lacks the typical exponential decay with water depth. The presence of a wave boundary layer is showcased and compared to an adaptation of the Stokes 2nd problem.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119759"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical assessment of incoming atmospheric boundary layer effects generated by various approaches on ship airwake turbulence characteristics","authors":"Ali Zamiri,&nbsp;Jin Taek Chung","doi":"10.1016/j.oceaneng.2024.119764","DOIUrl":"10.1016/j.oceaneng.2024.119764","url":null,"abstract":"<div><div>The unsteady and extensively separated turbulent airwake flows around a ship’s deck significantly impact helicopter pilot performance during shipboard operations. Hence, incorporating realistic, unsteady incoming mainstream conditions such as the atmospheric boundary layer (ABL), is crucial in numerical simulations of the ship airwake. This study employed delayed detached eddy simulations (DDES) to evaluate the effect of steady and unsteady ABL modeling methods on the turbulent flow characteristics of the ship airwake. A 1:12.5 scaled Simple Frigate Shape 1 (SFS1) ship model was utilized in the numerical simulations, and three distinct ABL profiles (one steady and two unsteady) were simulated at two different wind direction angles (HW and RW30). Synthetic and turbulator modeling methods were utilized to generate the unsteady ABL profiles. Time-averaged and instantaneous flow fields calculated by various ABL profiles were compared with experimental data at multiple points within the ship airwake. The numerical findings indicated that while the time-averaged data remained unaffected by the ABL profile presence, the instantaneous flow quantities experienced significant alterations, especially under the red wind condition. The introduction of an unsteady ABL profile was shown to augment the unsteadiness and fluctuation of the flow field within the ship airwake compared to the steady ABL scenario. Cross-correlation analyses between the velocity fields computed using steady and unsteady ABL profiles unveiled distinct patterns and behaviors of flow structures over the deck. Moreover, evaluation of the velocity and pressure fields of unsteady ABL across time/space domains revealed incremented turbulence and disturbances over the flight deck, intensifying with wind direction angle. The synthetic ABL modeling approach was found to deliver promising outcomes in comparison to the turbulator method, while requiring significantly lower computational resources.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119764"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722208","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":"Numerical investigation of local scour around a 2-degree of freedom vibrating subsea pipeline in steady flow under sagging condition","authors":"Vatsal Dhamelia,&nbsp;Ming Zhao,&nbsp;Pan Hu,&nbsp;Heath Palmer","doi":"10.1016/j.oceaneng.2024.119890","DOIUrl":"10.1016/j.oceaneng.2024.119890","url":null,"abstract":"<div><div>Numerical simulations are conducted to investigate the local scour below a sagging subsea pipeline vibrating in two degrees of freedom (2-DOF), covering a sagging ratio from −0.3 to 0 and a wide range of reduced velocities from 0.5 to 15. A negative sagging ratio means that the static balance position of the bottom surface of the pipeline is below the sand surface. The combined effects of the sagging and 2-DOF vibration of the pipeline on the scour are investigated. The maximum scour depth of the 2-DOF vibrating pipeline in the lock-in range of the vibration increases by 10% compared to the 1-DOF; however, the reduced velocity where the maximum scour depth occurs changes from 5 to 6. The variations of the vibration amplitude with the reduced velocity for all the sagging ratios follow a similar trend. For embedment ratios of −0.4 to −0.3, initial condition of scour simulation affects the equilibrium scour depth and vibration amplitudes. Simulations with a flat sand surface as initial condition prevent full scour development because the pipeline reaches its static balance position due to weak flow through the pipeline-to-bed gap. However, if the simulation starts with a sufficiently large initial scour depth, scour can reach its equilibrium.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119890"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New insights into local scour characteristics around vibrating monopiles under combined wave-current conditions","authors":"Zishun Yao ,&nbsp;Bruce Melville ,&nbsp;Asaad Y. Shamseldin ,&nbsp;Risheng Wang ,&nbsp;Dawei Guan","doi":"10.1016/j.oceaneng.2024.119812","DOIUrl":"10.1016/j.oceaneng.2024.119812","url":null,"abstract":"<div><div>Cyclic lateral vibrations on monopile foundations of offshore wind turbines throughout their service life may affect the local scour around the foundations. While previous studies have explored local scour around vibrating monopile foundations under current-only conditions, the local scour characteristics around these foundations under combined wave-current conditions remains unclear. This experimental study presents new insights into local scour characteristics around vibrating monopile foundations under combined wave-current conditions. A novel dimensionless parameter, the friction velocity-based Froude number (<em>Fr∗</em>), is proposed to quantify the effect of hydrodynamic intensity on the scour process. Based on the <em>Fr∗</em> values obtained in the experiment, three distinct regimes were identified to characterize the impact of vibrations on the scouring process: In Regime 1 (<em>Fr∗</em> &lt; 0.055), scour dimensions are more pronounced, while in Regime 3 (<em>Fr∗</em> &gt; 0.06), they are less significant compared to the equilibrium scour hole around static monopile foundations. In the transitional phase, Regime 2 (0.055 &lt; <em>Fr∗</em> &lt; 0.06), scour dimensions fluctuate by up to 10.9% relative to static conditions. Additionally, an estimation equation for equilibrium scour depth based on <em>Fr∗</em> is developed, demonstrating good prediction accuracy and broad applicability. These insights advance the understanding of scour features and provide a valuable reference for predicting scour depth around vibrating monopile foundations in diverse hydrodynamic environments.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119812"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722210","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":"Numerical investigation of the specific roll-heave coupled motion in an elastically connected twin barge float-over system","authors":"Shujie Zhao ,&nbsp;Dejiang Li ,&nbsp;Xun Meng ,&nbsp;Junfeng Du","doi":"10.1016/j.oceaneng.2024.119840","DOIUrl":"10.1016/j.oceaneng.2024.119840","url":null,"abstract":"<div><div>The concept of using an elastic connection between twin barge hulls and topsides offers an advantage in reducing the contact forces and topsides loads in a twin barge float-over (TBFO) system. However, due to the insufficient understanding of the complex motion characteristics of elastically connected multi-body systems, this operational mode has not yet been applied in marine engineering. To investigate the coupled motion characteristics of an elastically connected TBFO system, an experimental study was conducted. The results indicated that the topside's roll motion in such systems is greater than that of the barges under low-frequency wave conditions. Furthermore, a strong coupling exists between the topside's heave motion and the reverse roll motion of the twin barges. A numerical model for the TBFO system with elastic connections was developed and validated against physical model test results. Further numerical analysis revealed that the specific roll-heave coupled motions increase the topside's heave motion at low frequencies while reducing it in the higher frequency range. This suggests that the elastic connection could be effectively applied in TBFO operations under relatively short-wavelength sea conditions.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119840"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722209","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":"Numerical investigation on the suction caisson response considering seabed trenches and cyclic loading","authors":"Le Wang ,&nbsp;Tingran Zhang ,&nbsp;Xinglei Cheng ,&nbsp;Wanhai Xu ,&nbsp;Zhichao Shen ,&nbsp;Shengjie Rui ,&nbsp;Yinghui Tian","doi":"10.1016/j.oceaneng.2024.119839","DOIUrl":"10.1016/j.oceaneng.2024.119839","url":null,"abstract":"<div><div>As anchors of floating offshore structures, suction caissons endure cyclic loads transmitted by mooring chains. The moving chains repeatedly cut into the seabed, triggering the formation of trench, which further reduces the stability of suction caisson. However, the coupling effects of cyclic loading and trenches on the movement of suction caisson remain unexplored. To address this issue, finite element analyses were conducted to investigate the coupling effect of cyclic loading and trench on the movement of rigid suction in clay, employing a bounding surface constitutive model. The influences of cyclic amplitude, mean load, trench depth and width on the anchor behaviour are analysed. The results show that movement at the fixed loading point on the rigid caisson nonlinearly increases with the amplitude (<em>q</em>_am) and mean (<em>q</em>_me) of cyclic loading on a trenched seabed. This increase becomes pronounced when <em>q</em>_am exceeds 0.15, and <em>q</em>_me surpasses 0.35 the caisson's bearing capacity (<em>q</em>_ref). Additionally, trench dimensions significantly influence the caisson's movement. Specifically, trench depth has complex influence on the caisson's movement pattern, and increasing trench width results in larger movement, especially beyond a certain width. Considering the seabed trenches and cyclic loading, these findings offer valuable insight into the suction caisson movement.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119839"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722211","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":"Hydrodynamic performance of swimming fish in the wake region of a semi-cylinder","authors":"Hao Wang ,&nbsp;Saiyu Yuan ,&nbsp;Hongwu Tang ,&nbsp;Carlo Gualtieri ,&nbsp;Yuxiang Ling","doi":"10.1016/j.oceaneng.2024.119730","DOIUrl":"10.1016/j.oceaneng.2024.119730","url":null,"abstract":"<div><div>The characteristics of environmental vortices significantly influence the behavioral strategies of fish. This study investigated how wake vortices from obstacles affected propulsion and stability disturbances in fish behavior by numerically quantifying hydrodynamic effects related to different scales of semi-cylinders. The strong reverse flow in the recirculation regions of semi-cylinders generated trailing edge vortices near the tail, which reduced thrust and induced instability upon wake vortex impingement. Decreasing the gap between the semi-cylinder and the fish increased the duration of disruption. Additionally, passing wake vortices induced drag on fish tails and destabilized the fish when the gap between the vortices was small. Notably, for fish behind small semi-cylinders, wake vortex impingement did not cause drag and instability; rather, the primary source of drag was the shed wake vortices. These factors extended the disruption region laterally from the edges of the semi-cylinder to twice its diameter outside the wake region. Only the far downstream area, beyond the recirculation flow, could provide a beneficial turbulence environment with low-momentum flow. The findings of this study may enhance the understanding of vortex-fish interactions and offer valuable insights for the design and path planning of bio-inspired underwater vehicles.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119730"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722216","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":"Hydrodynamic characteristics of floating photovoltaic systems based on membrane structures in maritime environment","authors":"Lichao Xiong,&nbsp;Conghuan Le,&nbsp;Puyang Zhang,&nbsp;Hongyan Ding","doi":"10.1016/j.oceaneng.2024.119827","DOIUrl":"10.1016/j.oceaneng.2024.119827","url":null,"abstract":"<div><div>As the world confronts the pursuit of sustainable energy sources, floating photovoltaic (FPV) systems emerge as a focal point of innovation. As a novel FPV system, the membrane structure, owing to its advantages of lightweight design and economic feasibility, presents significant potential for widespread applications. Drawing inspiration from Ocean Sun's membrane prototype, this article devised a research model for the membrane structure. The initial phase involved a frequency-domain study. A 1:40 scale-down model was meticulously crafted for laboratory experiments, intended for comparison with numerical simulations. Conclusively, the amplitude response functions of the experimental scaled model aligned well with those of the numerically simulated scaled model and full-scale model. Moving forward, a time-domain study was conducted through numerical simulations to analyze the hydrodynamic responses of the prototype under combined wave and current loading. The findings revealed that the membrane structure have good seakeeping and stability. In comparison to the working sea state, the structural motion responses and mooring forces under survival sea state were significantly amplified. Notably, the mooring forces exhibited the most pronounced increase, surpassing a two-fold relationship. Subsequently, comparative analyses were conducted between membrane structures and FPV platforms in six relevant studies. It was found that the trends in RAO and wave interactions exhibited by these structures generally align with those observed in membrane structures.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119827"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722213","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 and experimental testing of a multi-tagline anti-sway and positioning system for slender-beam payload lifting during offshore operations","authors":"Maokai Sun ,&nbsp;Wanru Deng ,&nbsp;Zewen Sun ,&nbsp;Guangdong Han ,&nbsp;Shenghai Wang ,&nbsp;Hongpeng Zhang ,&nbsp;Yi Wei ,&nbsp;Yuqing Sun ,&nbsp;Zhiming Yuan","doi":"10.1016/j.oceaneng.2024.119790","DOIUrl":"10.1016/j.oceaneng.2024.119790","url":null,"abstract":"<div><div>To address the issues of anti-slip and anti-sway during the lifting of slender-beam payloads (SBP) in offshore environment, this paper presents a novel Multi-Tagline Anti-Sway and Positioning System (MTAPS). The entire lifting process is divided into two stages: the single-point lifting stage and the multi-tagline damping constraint stage. Dynamic modeling is performed at these two stages, and both Damping Control (DC) and Hierarchical Control (HC) strategies are designed for the MTAPS. Matlab/Simulink is used to analyze the dynamic characteristics of the SBP from the horizontal position to the lift-off stage. The sway reduction effect of the two MTAPS control strategies are then compared. Comprehensive experiments are conducted to validate the accuracy of the dynamic models and the effectiveness of the control methods. These experiments demonstrate that the MTAPS effectively mitigates the swinging of the SBP caused by single-point lifting, achieving an average reduction of sway motion by 86.25% during the suspension stage. The simulations and experiments shed lights on multi-tagline control strategies, as well as on the optimization of the offshore lifting process of SBP.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"315 ","pages":"Article 119790"},"PeriodicalIF":4.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722214","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}