Applied Ocean Research最新文献

{"title":"Experimental investigation of the asymmetric oscillation mechanism of an oscillating water column wave energy converter","authors":"Yuan Lin,&nbsp;Jiapeng Pan,&nbsp;Maoxing Wei,&nbsp;Fang He","doi":"10.1016/j.apor.2025.104557","DOIUrl":"10.1016/j.apor.2025.104557","url":null,"abstract":"<div><div>While numerous studies focus on the energy extraction rate of oscillating water column (OWC) converters, many assume symmetric water column oscillations within the flow field, despite observed discrepancies in real-world conditions. This study employs particle image velocimetry (PIV) to analyze flow field asymmetry under various regular wave conditions, with wave height being a key variable. Experimental results reveal significant differences in velocity distributions and flow patterns. At higher wave heights, a high-velocity region near the front wall of the OWC converter emerges as the primary outflow pathway, while the inflow largely adheres to the wave-induced flow velocity. These flow pattern variations closely correlate with the vortex evolution region. Further analysis uncovers asymmetry in vortex generation: the seaward vortex originates from a stable shear layer, whereas the leeward vortex forms through multiple flow separations and turbulent mixing. These vortices shape the asymmetric flow pattern, with the leeward vortex driving outflow near the front wall and the seaward vortex creating a high-velocity “curtain” that impedes water inflow. The inherent asymmetry in the flow field, minimal under weaker hydrodynamic conditions, becomes more pronounced at higher wave heights due to intensified vortex influences. Additionally, a symbiotic interaction between the seaward and leeward vortices is observed, where each influences the other's formation,This interplay ultimately impacts the overall flow dynamics and energy extraction efficiency.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104557"},"PeriodicalIF":4.3,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143807414","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":"LiDAR target detection and classification for ship situational awareness: A hybrid learning approach","authors":"Filippo Ponzini,&nbsp;Raphael Zaccone,&nbsp;Michele Martelli","doi":"10.1016/j.apor.2025.104552","DOIUrl":"10.1016/j.apor.2025.104552","url":null,"abstract":"<div><div>In recent years, LiDARs have been used to enhance situational awareness of autonomous vehicles, including in the marine domain, driven by the need for reliable detections in Marine Autonomous Surface Ships and Unmanned Surface Vehicles. Detecting obstacles and targets within point clouds is generally handled by a fully unsupervised learning framework. While effective and simple, this approach cannot classify targets. This paper presents a combined unsupervised/supervised approach for detecting and classifying marine targets and obstacles. The unsupervised detection framework is maintained by incorporating a lightweight supervised module capable of classifying detection outputs without disrupting the workflow. Rather than training on the entire point cloud, the proposed method focuses on selected target features, reducing model size and information exchange. Specifically, a Random Forest Classifier is trained on features extracted from the point-cloud dataset. The acquisition of an ad-hoc training dataset and its statistical analysis are presented to identify key features. The selection, training, and validation processes are outlined. Finally, the supervised model is integrated into a state-of-the-art unsupervised LiDAR detection pipeline and tested in a real scenario. The results demonstrate the hybrid framework’s effectiveness and compliance with real-time constraints.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104552"},"PeriodicalIF":4.3,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800204","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 cost elements on optimum layout of an offshore wind farm","authors":"Pegah Ziyaei,&nbsp;Mahdi Khorasanchi","doi":"10.1016/j.apor.2025.104537","DOIUrl":"10.1016/j.apor.2025.104537","url":null,"abstract":"<div><div>The main goal in wind farm layout optimization is to minimize the cost of energy (COE). This can be achieved by reducing the costs associated with the wind farm and/or increasing the power output, as both factors directly impact the COE. In this study, we focus on minimizing the levelized cost of energy (LCOE) by comprehensively considering all costs throughout the lifetime of a wind farm. To investigate the impact of the LCOE on optimization process, we examine a non-homogeneous wind farm. Consequently, we let the optimization process choose between two distinct categories of commercially available turbine sizes. The proposed cost model includes expenses associated with the key components involved in design, construction, and operation and maintenance processes throughout the wind farm's lifespan. Considering the change in wind speed, we first study two cases of identical turbines and a combination of different sizes of turbines by single and multi-objective optimization processes to minimize LCOE. While varying turbine sizes contribute to an increase in power production of the wind farm, the significant rise in elements of cost makes it impractical from a developer's perspective. Finally, we investigate the significance of considering different elements of cost in the objective function and emphasize the importance and superiority of the LCOE over the traditional COE.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104537"},"PeriodicalIF":4.3,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785256","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":"AI-driven 6-hour ahead nowcasting of sea-surface currents using HF Radar","authors":"Mattia Cavaiola ,&nbsp;Simone Marini ,&nbsp;Marcello G. Magaldi ,&nbsp;Andrea Mazzino","doi":"10.1016/j.apor.2025.104542","DOIUrl":"10.1016/j.apor.2025.104542","url":null,"abstract":"<div><div>This study introduces novel AI-driven models, Bidirectional Encoding-Forecasting (BiEF) and Variational Bidirectional Encoding-Forecasting (VBiEF), for nowcasting sea-surface currents using High Frequency (HF) Radar data. These models leverage advanced deep learning techniques to predict the dynamics of sea currents with accuracy and temporal resolution. Our research demonstrates that these AI models significantly outperform traditional persistence-based methods, providing skillful forecasts up to six hours ahead. While the VBiEF model, in particular, showcases good skill in capturing both the spatial and temporal complexities of sea currents, as well as in reconstructing intricate oceanographic features such as vorticity, divergence fields, and the rate of deformation tensor, several challenges remain to be addressed to further increase predictability levels. Furthermore, the good performance of these models in areas beyond their training domain suggests their adaptability and scalability for global ocean studies, opening new avenues for future research and application, highlighting the potential of AI in marine science.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104542"},"PeriodicalIF":4.3,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785257","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 particle crushing on the mechanical behavior of unreinforced and geogrid-reinforced marine coral sands","authors":"Zhaogang Luo ,&nbsp;Qiang Ou ,&nbsp;Xuanming Ding ,&nbsp;Ting Zhang ,&nbsp;Jinqiao Zhao","doi":"10.1016/j.apor.2025.104555","DOIUrl":"10.1016/j.apor.2025.104555","url":null,"abstract":"<div><div>Strength deterioration induced by particle crushing is detrimental to the construction of marine geo-structures. As an efficient reinforcement method, the geogrid-reinforced coral sand (GRCS) technique also suffers from the adverse effects of particle crushing. In this study, the macro-micro mechanical behavior of unreinforced and geogrid-reinforced coral sands under triaxial loading was investigated using an experimentally validated three-dimensional discrete element method (DEM), focusing on the effect of particle crushing. The results reveal that crushability determines the stress-strain response, strength parameters, spatial distribution of crushing, and number of particle fragments differently. The analysis of microscopic contact forces indicates that the resistance pattern of GRCS under triaxial loading results in the gap in spatial distribution patterns and the number of fragments compared with the unreinforced condition. Further micro-scale analysis of the crushing behavior shows that the increased fragments induce a transition of the particle morphology from angular to round-like patterns, thus the low occlusion and increased plasticity of crushed coral sands contribute to the stress-strain softening and peak strength reduction. In conjunction with the effect of crushing on shear strength, the strength envelope characteristics and the evolution mechanism of shear mechanical parameters are revealed under the effects of reinforcement, low crushing, and high crushing.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104555"},"PeriodicalIF":4.3,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783065","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":"Calibration of medium-range metocean forecasts for the North Sea","authors":"Conor Murphy ,&nbsp;Ross Towe ,&nbsp;Philip Jonathan","doi":"10.1016/j.apor.2025.104538","DOIUrl":"10.1016/j.apor.2025.104538","url":null,"abstract":"<div><div>We assess the value of calibrating forecast models for significant wave height <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>S</mi></mrow></msub></math></span>, wind speed <span><math><mi>W</mi></math></span> and mean spectral wave period <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>m</mi></mrow></msub></math></span> for forecast horizons between zero and 168 h from a commercial forecast provider, to improve forecast performance for a location in the central North Sea. We consider two straightforward calibration models, linear regression (LR) and non-homogeneous Gaussian regression (NHGR), incorporating deterministic, control and ensemble mean forecast covariates. We show that relatively simple calibration models (with at most three covariates) provide good calibration and that addition of further covariates cannot be justified. Optimal calibration models (for the forecast mean of a physical quantity) always make use of the deterministic forecast and ensemble mean forecast for the same quantity, together with a covariate associated with a different physical quantity. The selection of optimal covariates is performed independently per forecast horizon, and the set of optimal covariates shows a large degree of consistency across forecast horizons. As a result, it is possible to specify a consistent model to calibrate a given physical quantity, incorporating a common set of three covariates for all horizons. For NHGR models of a given physical quantity, the ensemble forecast standard deviation for that quantity is skilful in predicting forecast error standard deviation, strikingly so for <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>S</mi></mrow></msub></math></span>. We show that the consistent LR and NHGR calibration models facilitate reduction in forecast bias to near zero for all of <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>S</mi></mrow></msub></math></span>, <span><math><mi>W</mi></math></span> and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>m</mi></mrow></msub></math></span>, and that there is little difference between LR and NHGR calibration for the mean. Both LR and NHGR models facilitate reduction in forecast error standard deviation relative to naive adoption of the (uncalibrated) deterministic forecast, with NHGR providing somewhat better performance. Distributions of standardised residuals from NHGR are generally more similar to a standard Gaussian than those from LR.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104538"},"PeriodicalIF":4.3,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143748584","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":"Observed changes in significant wave heights derived from long-term homogenized measurements offshore mainland Portugal","authors":"Rita Esteves ,&nbsp;Diogo Mendes ,&nbsp;Maria Graça Neves ,&nbsp;Tiago Oliveira ,&nbsp;José Paulo Pinto","doi":"10.1016/j.apor.2025.104546","DOIUrl":"10.1016/j.apor.2025.104546","url":null,"abstract":"<div><div>Trends in wind-wave climates across the globe have been primarily addressed using numerical models. Availability of long-term data collected by wave buoys is often scarce and they present inhomogeneities associated with wave buoy size and hardware over time. Here, a trend analysis was conducted on approximately 40 years of homogeneous wind-wave data collected by wave buoys offshore mainland Portugal. For that, a homogenization methodology based on RHTestsV4, with ERA5 wave hindcast as reference time series was used. Results indicate that along the north-western coastline facing the North Atlantic, an increasing trend of monthly mean significant wave height of +10 mm/yr was observed at FigLei record for the months between October and December. Along the south-western coastline, no statistically significant trends were observed. Along the southern coastline, which is also exposed to wind-waves generated in the Mediterranean Sea results at Faro record show a decreasing trend of monthly 90th percentile of -22.2 mm/yr between October and December. A further comparison between the wind-wave trends obtained with local wave buoys and those from the global ERA5 wave hindcast highlights that the trends of the later can be opposite, or they can vary by up to a factor of 10 which emphasizes the importance of long-term wave buoy observations networks for a more accurate understanding of local wave climates.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104546"},"PeriodicalIF":4.3,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738755","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 investigation of coarse granular flow of the Coandă effect-based collector over logarithmic spiral surface for deepsea mining","authors":"Hao Jia,&nbsp;Ya-peng Wang,&nbsp;Jian Yang","doi":"10.1016/j.apor.2025.104540","DOIUrl":"10.1016/j.apor.2025.104540","url":null,"abstract":"<div><div>As an emerging hydraulic harvester for deep-ocean polymetallic nodules, Coandă effect-based collectors aim to minimize seabed disturbance while maintaining high collector efficiency. This study employs CFD-DEM simulations to analyze a logarithmic spiral collector with non-dimensional parameters (<em>s/R</em> = 1, 2/3, 1/2), focusing on jet dynamics and particle trajectories. Results reveal that the near-wall jet entrains ambient flow, creating a high-pressure zone at the collection pipe inlet. The merged flow ascends asymmetrically toward the tube, inducing a reflux vortex. Jet expansion is quantified via normalized half-width (<em>y_1/2m</em>/<em>h</em>), showing a linear growth rate (∼10 % per <em>s/h</em> increment) along the logarithmic spiral. Turbulence effects are characterized by wall Reynolds number (<em>Re_w</em>) and local Reynolds number (<em>Re_b</em>): <em>Re_b</em> increases monotonically with <em>s</em>, while <em>Re_w</em> first decreases then increases due to delayed boundary layer development, independent of <em>s/R</em>. Particle motion exhibits four distinct lift phases, with higher <em>s/R</em> ratios enhancing sustained horizontal jet velocity components, thereby accelerating particle velocity during lift and revolution stages. These findings systematically clarify interactions between spiral geometry, flow dynamics, and particle transport, offering direct guidance for optimizing Coandă effect-based collectors to reduce seabed environmental impact. The proposed metrics (<em>y_1/2m</em>/<em>h, Re_w, Re_b</em>) establish quantitative benchmarks for evaluating hydraulic performance in deep-sea mining applications.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104540"},"PeriodicalIF":4.3,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738754","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 study of nonlinear hydrodynamic and mooring modelling for the Volturn floating wind platform in comparison with experiments","authors":"Yi Zhang ,&nbsp;Peter Stansby ,&nbsp;Gangqiang Li","doi":"10.1016/j.apor.2025.104550","DOIUrl":"10.1016/j.apor.2025.104550","url":null,"abstract":"<div><div>For coupled hydrodynamic-aerodynamic-mooring models for floating offshore wind platforms, there has been little time domain validation against experimental data which can reveal the origin of uncertainties for this complex problem. Here we use data for focussed waves incident on the 15 MW Volturn semi-submersible platform at 1:70 scale and free decay tests where fairlead tensions and instantaneous platform position have been measured. This enables mooring models to be assessed independently with known fairlead motions. The catenary chain moorings are modelled by quasi-static theory and in lumped-mass form including dynamics and damping using the MoorDyn code. Tension predictions by MoorDyn with fairlead motion input were always highly accurate in both free decay and focussed waves while quasi-static theory only gave equivalent accuracy in surge decay tests. In relatively large focussed waves, motion prediction by coupled modelling was substantially improved by including the instantaneous platform position in the excitation force formulae, giving a simple nonlinear extension within an otherwise linear model (apart from the drag formulation). Both mooring models gave similar predictions of platform motion in free decay and focussed waves generally approximating experimental results. While mooring tension was well predicted by MoorDyn in all cases, quasi-static modelling again only gave good prediction for surge free decay. Irregular wave interactions at full-scale have also been simulated with wind thrust effect and the statistics of the platform motions and fairlead tensions are analysed, showing the importance of dynamic mooring effects on mooring fatigue but with little effect on maximum tension or platform motion.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104550"},"PeriodicalIF":4.3,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735048","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":"Inclined pullout capacity of suction anchors in clay-silty sand-clay soil deposits","authors":"Chuhao Long ,&nbsp;Rucong Liang ,&nbsp;Mi Zhou ,&nbsp;Jinhui Li ,&nbsp;Xihong Zhang","doi":"10.1016/j.apor.2025.104549","DOIUrl":"10.1016/j.apor.2025.104549","url":null,"abstract":"<div><div>This study focuses on two types of suction anchor foundations frequently used in wind power projects, evaluated through numerical modeling to assess their pullout capability under inclined mooring loading in a clay-silty sand-clay-soil deposits. A finite element model was generated and validated against existing data with good agreement. A parametric study was then conducted to investigate the effects of geometric variation, including the interbedded silt sand, padeye positioning, and soil material properties. Key design factors identified from the simulations include: (1) the optimized padeye position, (2) the ultimate horizontal (or lateral) and vertical pullout abilities, and (3) the horizontal (or lateral) load distributions at different padeyes. Finally, based on the results of numerical analysis, an empirical design approach was proposed, along with a design method that enhances current guidelines for more accurate prediction of anchor pullout capacity in clay-silty sand-clay soil deposits.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104549"},"PeriodicalIF":4.3,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735047","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}