Applied Ocean Research最新文献

{"title":"Short-term significant wave height prediction using adaptive variational mode decomposition and error-compensation model","authors":"Junheng Pang,&nbsp;Sheng Dong","doi":"10.1016/j.apor.2025.104519","DOIUrl":"10.1016/j.apor.2025.104519","url":null,"abstract":"<div><div>Significant wave height (Hs) is a critical parameter for the design of offshore structures and marine construction planning. Recently, pre-processing techniques have been extensively employed to enhance the performance of Hs predictions. Although variational mode decomposition (VMD) has been proven as an effective tool, it is not parameter-adaptive, and manual parameter selection introduces significant uncertainty. To address this issue, an adaptive VMD method, termed GAVMD, is developed, integrating the grey wolf optimizer (GWO), attention entropy (AE), and VMD. Furthermore, the gated recurrent unit (GRU) and extreme learning machine (ELM) are combined into an error-compensation model (GRU-ELM) to perform prediction tasks. By integrating GAVMD with the error-compensation model, a novel hybrid model, GAVMD-GRU-ELM, is proposed for Hs prediction. To validate the proposed model, two single models, ELM and GRU, as well as two hybrid models, VMD-GRU and GAVMD-GRU, are adopted as baselines. The experimental results demonstrate that while single models perform adequately for 3-h predictions, they fall short for 6-h forecasts. In contrast, hybrid models consistently achieve accurate predictions, benefiting from VMD or GAVMD, with GAVMD showing superior improvement compared to VMD. In all prediction scenarios, GAVMD-GRU-ELM outperforms the other models, indicating that the error-compensation model effectively enhances forecast accuracy.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104519"},"PeriodicalIF":4.3,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619772","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":"Nonlinear analysis and weight optimization of living quarters for offshore jack-up rigs: A sustainable engineering approach","authors":"Myung-Su Yi ,&nbsp;Joo-Shin Park","doi":"10.1016/j.apor.2025.104515","DOIUrl":"10.1016/j.apor.2025.104515","url":null,"abstract":"<div><div>The living quarters (LQ) on jack-up rigs play a critical role in ensuring crew safety and operational functionality under extreme offshore conditions. This study presents a comprehensive structural engineering procedure for the design and analysis of LQ structures, addressing the absence of specific industry standards. The methodology integrates global and local load effects from critical equipment, such as helidecks and lifeboat stations, under harsh environmental conditions during wet towing. A multi-level analysis approach, including finite element analysis (FEA), nonlinear evaluations, and fatigue assessments, was employed to verify structural resilience. The study successfully validates the LQ structures against ultimate limit state (ULS), serviceability limit state (SLS), and accidental limit state (ALS) criteria. The maximum plastic strain observed under green water pressure was 3.8 %, well below the allowable threshold of 15 %, demonstrating adequate safety margins. Fatigue analysis confirmed resistance to vortex-induced vibrations (VIV), ensuring the durability of tubular members. Optimization efforts reduced LQ structural weight by 20 %, enhancing efficiency without compromising safety. The proposed procedure bridges the gap in industry standards, providing a robust framework for designing safer and more reliable LQ structures. This study advances offshore engineering practices by addressing complex loading scenarios and operational challenges, thereby supporting the development of resilient jack-up rigs capable of enduring extreme marine conditions.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104515"},"PeriodicalIF":4.3,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619771","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":"Assessing the need for artificial data in offshore operability calculations","authors":"Øystein Døskeland ,&nbsp;Svein Sævik ,&nbsp;Zhen Gao ,&nbsp;Petter Moen","doi":"10.1016/j.apor.2025.104499","DOIUrl":"10.1016/j.apor.2025.104499","url":null,"abstract":"<div><div>Offshore operations are frequently delayed by weather conditions that exceed operational limits. While such delays are expected, it is challenging to estimate them at an early point in a project. Accurate estimates are beneficial for bidding contracts, planning vessel schedules, optimizing operation sequences, and reducing commercial risk and costs. Models that generate artificial but representative time series data have previously been proposed to increase the statistical confidence in weather waiting estimates. In this study, two existing methods that rely on artificially generated data, a Markov Chain model and a VAR (Vector Auto-Regressive) model, were studied and compared against a method that directly relies on 48 years of NORA3 hindcast data. The modelling errors that are introduced with the artificial data are difficult to quantify and are found to vary with different schedules and the season. Such methods are not recommended for cost estimation on projects that may be included in a portfolio strategy. Instead, the weather waiting may be calculated directly from hindcast data, and the confidence intervals may be quantified using the Bootstrap Method, which was found to perform better than analytical alternatives. However, if sufficient effort is spent to validate the results, the use of artificial data may be informative for cases where the stakes and the uncertainties are particularly high, such as for operations performed during the late fall and winter season in the North Sea region.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104499"},"PeriodicalIF":4.3,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619320","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":"Experimental investigation of the breakwater consisting of an array of cylindrical oscillating water column devices: Hydrodynamic characteristics and wave energy conversion","authors":"Jiapeng Pan,&nbsp;Yuan Lin,&nbsp;Junfei Hong,&nbsp;Fang He","doi":"10.1016/j.apor.2025.104520","DOIUrl":"10.1016/j.apor.2025.104520","url":null,"abstract":"<div><div>Integrating OWC into breakwater is a win-win program that accomplishes function expansion and cost-sharing. In the present study, a non-intercepting breakwater, integrated with an array of cylindrical OWCs aligned linearly with a certain distance, is proposed and experimentally studied, emphasizing the hydrodynamic characteristic and wave energy conversion. The superiority of the proposed OWC-type breakwater in coastal protection is affirmed by comparing hydrodynamic experiments of three specific configurations. The effects of the OWC array's porosity, wave height, and draft on the hydrodynamic characteristics and wave energy conversion are investigated in detail. Under an array layout, the hydrodynamic interaction between devices contributes significantly to the hydrodynamic response of OWC. When the cylindrical OWC array has a porosity of 0.2 to 0.6, the wave energy conversion is improved in terms of both a larger peak efficiency value and a broader efficient frequency bandwidth. A smaller porosity can result in a larger second-order wave component in the wave at the center of adjacent OWC devices. In addition, the wave transmission can be effectively suppressed by decreasing the OWC array's porosity or increasing the device's draft. In practice applications, the OWC array's porosity needs to be determined flexibly according to the project objectives.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104520"},"PeriodicalIF":4.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619770","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":"A unified FSI framework for modeling liquid sloshing and baffle suppression in the elastic tank","authors":"Chenxi Zhao ,&nbsp;Yan Wu ,&nbsp;Yongchuan Yu ,&nbsp;Oskar J. Haidn ,&nbsp;Xiangyu Hu","doi":"10.1016/j.apor.2025.104498","DOIUrl":"10.1016/j.apor.2025.104498","url":null,"abstract":"<div><div>The dynamic and highly nonlinear nature of liquid sloshing in liquefied natural gas (LNG) tanks necessitates accurate numerical modeling to ensure structural integrity and operational safety during maritime transport. However, existing studies often overlook detailed stress and strain distributions within tank walls, which limits the assessment of structural reliability. Additionally, traditional fluid–structure interaction (FSI) approaches typically adopt separate solvers for fluid dynamics and structural mechanics, leading to data transfer errors and interpolation inaccuracies. To address these challenges, this study employs a unified smoothed particle hydrodynamics (SPH) framework for simulating liquid sloshing and its interaction with elastic tank structures. The effects of single- and multi-resolution schemes, as well as single- and multi-phase formulations, are systematically analyzed to assess their influence on numerical accuracy and computational efficiency, through validation against experimental data. The results demonstrate the reliable precision of the proposed multi-phase and multi-physics FSI model in predicting free-surface elevation, pressure distribution, and structural deformation. Furthermore, the study explores the effectiveness of various baffle configurations in mitigating sloshing-induced forces and structural deformations, providing insights into their role in mitigating hydrodynamic loads on tank structures.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"157 ","pages":"Article 104498"},"PeriodicalIF":4.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610700","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":"Effect of flow deflectors on local scour around artificial reefs under steady current: Experimental and numerical investigations","authors":"Xianyi Liu,&nbsp;Xinxin Wang,&nbsp;Fenfang Zhao,&nbsp;Huaxiang Sheng","doi":"10.1016/j.apor.2025.104509","DOIUrl":"10.1016/j.apor.2025.104509","url":null,"abstract":"<div><div>Artificial reefs are submerged structures used to rehabilitate marine ecosystems and restore fishery resources. Field investigations have revealed that local scour poses a significant threat to these structures in various regions. Despite this, there is limited research on scour countermeasures for artificial reefs and a lack of understanding regarding the flow patterns that influence scour. This study examines the effects of different deflectors on scour depth and flow patterns around artificial reefs, focusing on a control model (AR1) and an optimized model (AR11). The experiments were conducted under steady, unidirectional current conditions. Flume experiments demonstrated that AR11 reduced the maximum scour depth by approximately 46 % compared to AR1 and effectively prevented reef tilting. Flow fields on the scour bed of AR1 and AR11 were reconstructed using hydrodynamic modelling of scour topography and computational fluid dynamics (CFD). The analysis revealed that the main flow features affecting the scour around AR1 were a counterclockwise vortex on its side and a vortex within the scour hole. In contrast, AR11 effectively mitigated the adverse effects of these vortices, thereby reducing scour around the artificial reef.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"157 ","pages":"Article 104509"},"PeriodicalIF":4.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610701","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":"An extended two-layer viscous Boussinesq-type model for surface gravity waves: Including the effect of bottom friction","authors":"Hao Sun ,&nbsp;Yang Zhao ,&nbsp;Zhongbo Liu ,&nbsp;Yong Liu","doi":"10.1016/j.apor.2025.104495","DOIUrl":"10.1016/j.apor.2025.104495","url":null,"abstract":"<div><div>Wave propagation is accompanied by energy attenuation owing to the water viscosity. Based on the two-layer viscous Boussinesq-type model considering of deep-water waves, the bottom friction term is incorporated to further simulate wave energy dissipation for limited-depth and shallow water waves. The viscous effects at the free surface and the seabed are analyzed based on analytical linear dispersion. Linear dispersion relation of present model is obtained using Stokes-type Fourier analysis and compared with the analytical solution, where the linear phase celerity and damping rate of the model is accurate for <em>h</em>/<em>L</em>₀ ≤ 8.0 and 5.22 (<em>h</em> is water depth and <em>L</em>₀ is characteristic wavelength) within 1% error, respectively. The finite difference method is employed for numerical implementation, and the computed results are compared with analytical solutions and related experimental data. Remarkable agreements demonstrate the accuracy of the numerical procedure and verify the importance of bottom friction. This article discusses the dimensionless water depth corresponding to the maximum damping rate caused by bottom friction and comparing the different methods to consider bottom friction. The value of bottom friction coefficient is also explored based on experiments.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"157 ","pages":"Article 104495"},"PeriodicalIF":4.3,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143593206","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":"Global evaluation of wave data reanalysis: Comparison of the ERA5 dataset to buoy observations","authors":"Victoria Bessonova ,&nbsp;Evdokia Tapoglou ,&nbsp;Robert Dorrell ,&nbsp;Nina Dethlefs ,&nbsp;Katharine York","doi":"10.1016/j.apor.2025.104490","DOIUrl":"10.1016/j.apor.2025.104490","url":null,"abstract":"<div><div>Wave reanalysis data are critical to multiple industries including commerce, fisheries, petroleum, offshore wind, the design and the construction of maritime structures. One of the most used datasets is ERA5 developed by the European Centre for Medium Range Forecast. The accuracy and reliability of this dataset have not been rigorously assessed on a global scale. We present the first global evaluation of ERA5 significant wave height against measurements from 444 buoys worldwide. We demonstrate the influence of critical control factors including distance to shore, water depth, regional characteristics and seasonality. Results showed that ERA5 underestimates significant wave height in extreme conditions. This underestimation could lead to underestimating the severity of predicted wave conditions when designing vessels or foundations for maritime structures. ERA5 accuracy increases farther from shore, but does not change significantly with increasing water depth. In the Northern Hemisphere, the RMSE and absolute bias between ERA5 and measured significant wave height are up to 0.25 m lower in summer than in winter. Seasonal patterns are less pronounced in the Southern Hemisphere. The results provide global confidence levels for the robust use of ERA5 data, and establish a methodology to test future datasets.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"157 ","pages":"Article 104490"},"PeriodicalIF":4.3,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143593205","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 study on internal waves generated by a submerged body moving in two types of stratified fluids","authors":"Xuebin Chen ,&nbsp;Shuqun Cai ,&nbsp;Jiexin Xu ,&nbsp;Shuyan Deng","doi":"10.1016/j.apor.2025.104513","DOIUrl":"10.1016/j.apor.2025.104513","url":null,"abstract":"<div><div>A numerical model is employed to simulate the internal waves generated by a moving submerged body in stratified fluids through the joint solution of the Navier-Stokes equations and the density transport equation. It is found the generation of internal waves begins with the formation of elevation and depression regions at the front and rear ends of the submerged body. As the body moves, more pairs of elevation and depression regions emerge in the wake, progressively leading to the full evolution of divergent and transverse wave features. Internal waves generated in two types of stratified fluids are compared, inferring the similarity of internal waves between two stratified fluids is not restricted to a specific depth but is consistently observed across all depths, and this similarity encompasses main flow characteristics, including internal wave surface fluctuation, pressure, and velocity components. However, an equivalent of Froude number, Fr, is only a necessary condition for the similarity, which does not guarantee the similarity between cases with different density stratifications. A water depth-based Froude number, Fr’(z), is proposed in this paper to investigate similarity. It has been shown that similarity is ensured when the Fr’(z) values of these cases are equal at any water depth.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"157 ","pages":"Article 104513"},"PeriodicalIF":4.3,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143593203","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":"Sea level forecasting using deep recurrent neural networks with high-resolution hydrodynamic model","authors":"Saeed Rajabi-Kiasari ,&nbsp;Artu Ellmann ,&nbsp;Nicole Delpeche-Ellmann","doi":"10.1016/j.apor.2025.104496","DOIUrl":"10.1016/j.apor.2025.104496","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Changes in climate, along with increasing marine activities in coastal and offshore regions, highlight the need for effective sea level forecasting methods. In recent years, forecasting techniques, especially those utilizing machine learning/deep learning methods (ML/DL), have shown promising capabilities. However, sea level forecasting is often limited in accuracy and spatiotemporal coverage, primarily due to the challenges posed by available observational data, which complicates the assessment of existing ML/DL techniques in complex and dynamic regions like the Baltic Sea. This study addresses these challenges by utilizing a high-resolution spatiotemporal framework that integrates high-resolution hydrodynamic and marine geoid models available to Baltic countries, enabling further capabilities to be explored in terms of sea level accuracy and validation. Specifically, it examines short-term sea level forecasting in the eastern Baltic Sea and the potential of utilizing two recurrent neural network-based models such as the Long Short-Term Memory Networks (LSTMs), and the Gated Recurrent Unit (GRU) along with high-resolution input data sources. These models were specifically chosen, due to their expected capabilities with time series data and their ability to learn both short and long-term connections of the input datasets.&lt;/div&gt;&lt;div&gt;To achieve this, a multivariate multistep-ahead (3, 6, 9, 12, and 24 h) forecasting framework was developed. The DL models' input components are high-resolution sea level data obtained from a bias-corrected hydrodynamic model, wind speed, surface pressure, and sea surface temperature. Results for various time steps (from 3 h to 24 h ahead), during the test period, revealed that the two DL models generally showed similar performance, with slightly superior results with the GRU model. For instance, GRU and LSTM showed an averaged root mean square error (RMSE) of 4.96 cm and 5.3 cm and a coefficient of determination (R²) of 0.93 and 0.92, respectively. Investigations of the time series forecasting performance at selected locations, also demonstrated the superiority of the GRU model, for all time steps, with Willmott's index (WI) values generally above 0.9 and high reliability as reflected in Prediction Interval Coverage Probability (PICP) values mostly exceeding 90 %. The results, however, weren't always perfect; both the GRU and LSTM models encountered limitations with forecasting the sea level maxima. Further examination of the spatial discrepancies also reveals some problematic areas in the eastern Gulf of Finland. This may have been influenced by the exclusion of some input components such as river discharge, salinity and meridional winds, further enhanced by complex hydrodynamics, extreme sea level variations, strong local currents, resonance-induced seiches and seasonal ice cover. In addition, an external validation of the GRU results was performed using along-track satellite altimetry from Sentinel 3A and","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"157 ","pages":"Article 104496"},"PeriodicalIF":4.3,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579608","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}