Applied Ocean Research最新文献

{"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}

{"title":"An empirical methodology for bend stiffener sizing","authors":"Rui Zhen ,&nbsp;Chen Shi ,&nbsp;Xingxian Bao","doi":"10.1016/j.apor.2025.104518","DOIUrl":"10.1016/j.apor.2025.104518","url":null,"abstract":"<div><div>A flexible riser hanging from an offshore platform may experience excessive curvatures at the hang-off zone due to the stiffness discontinuity between the riser and its attachment point. To mitigate this issue, a bend stiffener is typically installed to gradually increase the bending stiffness of the riser’s upper section, thereby limiting the curvature. Previous studies have modeled a bend stiffener, often with a conical profile, as a cantilever beam. The structural analysis of this beam results in a second-order nonlinear differential equation with variable coefficients. While an explicit analytical solution for this equation is not available, a numerical solution can be obtained using advanced mathematical algorithms, which can be implemented through commercial or open source software. This paper introduced an empirical procedure for designing a bend stiffener. The riser’s hang-off section, including the bend stiffener, is modeled as a cantilever beam. It is assumed that at a certain distance from the tip of the bend stiffener, the bending moment of the riser approaches zero. At this “zero-moment” point, the axial tension force and rotation angle of the riser can be obtained from global dynamic analyses of the riser. The procedure begins by determining the length of the riser section between the zero-moment point and the tip of the bend stiffener. With this length known, the shear force, tension force, and bending moment at the tip of the bend stiffener can be calculated based on the equilibrium of the riser section. The second part of the procedure involves estimating the dimensions of the bend stiffener, particularly the length and outer diameter of its conical section. To avoid relying on advanced mathematical algorithm, the bend stiffener is simplified as a series of short segments, with each segment modeled as a cantilever beam with a constant cross-section. Starting from the tip of the bend stiffener, the length and outer diameter of each successive segment were estimated iteratively from equilibrium, deformation equations, and material mechanics. The proposed empirical procedure was compared with previous studies and validated using finite element analysis simulations. Results showed that the empirical procedure offered a practical tool for the preliminary design of a bend stiffener.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104518"},"PeriodicalIF":4.3,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143724166","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":"Fast real-time prediction of wave exciting force for a point absorber based on impulse response functions","authors":"Ryo Yoshimura,&nbsp;Takahito Iida,&nbsp;Md Shahidullah Kaiser,&nbsp;Kazuki Irifune","doi":"10.1016/j.apor.2025.104539","DOIUrl":"10.1016/j.apor.2025.104539","url":null,"abstract":"<div><div>Fast real-time prediction of wave exciting forces is necessary for the optimal control of Point Absorbers (PAs) in wave energy conversion. However, the non-causality of the impulse response function (IRF) of wave exciting force is a crucial issue for the prediction. To address this problem, this study employs deterministic wave prediction using upstream measured wave data. By integrating the IRFs of water waves and wave exciting forces, a real-time prediction method of wave exciting force is developed. Once the wave exciting force can be estimated, body motion, outgoing waves, and energy absorption efficiency are easily determined. For the verification of the proposed method, regular wave analysis is carried out, and numerical results are compared with those obtained from the frequency domain analysis using the two-dimensional boundary element method (2D-BEM). The results are also verified by the energy conservation principles. Through these verifications, it is shown that the proposed results strongly agree with the 2D-BEM results. Additionally, the real-time applicability is evaluated using the real-time factor (RTF). It is shown that the method achieves RTFs less than <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math></span>; computational efficiency and practical feasibility are demonstrated.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104539"},"PeriodicalIF":4.3,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716092","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":"Feasibility assessment of enhancing permeability and stability in marine hydrate reservoirs with dual-enhanced stimulation: Slurry-sediment cementation characteristics","authors":"Fang Jin,&nbsp;Feng Huang,&nbsp;Guobiao Zhang,&nbsp;Bing Li,&nbsp;Yanchao Liu,&nbsp;Jianguo Lv","doi":"10.1016/j.apor.2025.104545","DOIUrl":"10.1016/j.apor.2025.104545","url":null,"abstract":"<div><div>Natural gas hydrate reservoirs in the South China Sea exhibit weak cementation, low strength, and low permeability, which severely restricts their commercial viability. To overcome these challenges, we propose an innovative dual-enhanced stimulation method involving slurry injection via splitting grouting. This slurry undergoes <em>in-situ</em> solidification, forming porous, high-strength, and high-permeability channels. The method's success hinges on understanding cementation patterns between the slurry and reservoir sediments, along with the permeability dynamics at the cementation interface. This study explored the microscopic features of the slurry-sediment cementation interface and evaluated changes in permeability nearby and within the slurry-sediment composite. It was observed that during the solidification process, the slurry invaded the sediments, resulting in an interface thickness more than 55µm. This invasion altered the pore structure of the sediment at the interface, reducing its porosity by more than 40 %, which in turn decreased gas permeability and damaged the permeability of the slurry-sediment coupled sample. After consolidation, the permeability damage of the coupled sample reached about 75 %, but it decreased to 27 % with the discharge of the permeability-enhancer in the slurry. Additionally, the evaluation of the pressure drop coefficient revealed that hydrate reservoirs stimulated with polyurethane slurry exhibit superior permeability compared to those transformed with guar gum fracturing fluid and pure water. This suggests that the dual-enhanced stimulation slurry causes minimal damage to reservoir permeability, demonstrating its feasibility in enhancing both permeability and strength of the reservoir. This study presents a novel stimulation method for the safe and efficient extraction of marine hydrates.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104545"},"PeriodicalIF":4.3,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716093","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":"Structural responses of offshore multi-body floating photovoltaic array under different connection conditions","authors":"Tao Zou ,&nbsp;Jian Jiang ,&nbsp;Haijun Li ,&nbsp;Junfeng Du ,&nbsp;Longbin Tao","doi":"10.1016/j.apor.2025.104544","DOIUrl":"10.1016/j.apor.2025.104544","url":null,"abstract":"<div><div>The connector design plays a pivotal role in ensuring the structural integrity and operational efficiency of offshore floating photovoltaic (FPV) systems. This study aims to systematically investigate the impact of various connection types (rigid, rubber, hinged, and flexible) on the hydrodynamic response of offshore FPV arrays, as well as on the structural responses of their connectors. Firstly, a single-float model was developed, and the hydrodynamic coefficients necessary for the time-domain analysis were meticulously derived using frequency-domain methods. Subsequently, a 3 × 3 FPV array model was constructed, including the connectors with specifications tailored to the stiffness and constraints of the four distinct connection types. Finally, a comparative analysis was conducted on the motion responses of the three representative modules (central, edge, and corner), along with the corresponding connectors’ responses. This study demonstrates that floats interconnected by rigid connectors are most significantly influenced by the surrounding floats. The outer floats, in conjunction with their connectors, constitute an outer-frame integrity phenomenon that plays a critical role in maintaining the array stability. Furthermore, the fatigue cycles experienced by the connectors attached to corner modules exhibited an increased sensitivity to the incident wave angle, highlighting the importance of precise wave direction considerations.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104544"},"PeriodicalIF":4.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704772","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":"Control co-design for wave energy systems","authors":"John V. Ringwood","doi":"10.1016/j.apor.2025.104514","DOIUrl":"10.1016/j.apor.2025.104514","url":null,"abstract":"<div><div>Control co-design (CCD) has become a powerful paradigm in the total optimisation of the dynamics of a system against a defined performance goal. Given the impact of control on wave energy systems, including significant effects on motion and energy capture performance, it is imperative that controller and system are optimised together to maximise (economic) system performance. There are a number of design aspects that can usefully be addressed by CCD in wave energy systems, including device geometry, mooring configuration, power take-off (PTO) parameters, and array layout. A number of these design aspects present significant computational challenges and, as a result, wave energy CCD studies typically address a single design aspect at a time. This paper examines the useful roles that CCD can play in wave energy systems, important criteria to consider, and the potential interaction between individual wave energy CCD aspects.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104514"},"PeriodicalIF":4.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704770","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}