Applied Ocean Research最新文献

{"title":"Active flow control on unsteady cloud cavitation: Insights into jet dynamics","authors":"","doi":"10.1016/j.apor.2024.104152","DOIUrl":"10.1016/j.apor.2024.104152","url":null,"abstract":"<div><p>Unsteady cloud cavitation significantly impairs the performance of marine systems. Active flow control method has shown promise in effectively reducing cavitation, yet its specific mechanisms of action require elucidation. This study investigates continuous water injection on a NACA66 (MOD) hydrofoil as an active control against unsteady cloud cavitation. Results show notable reductions in cavitation volume: 52.57 % at a cavitation number of 0.83 and 86.24 % at 1.29. Employing the Lagrangian approach, the study tracks ideal particles to explore the jet's behavior and its interaction with cavitation. The interaction between the jet and cavitation is reciprocal: cavitation draws the jet, which in turn alters the cavitation's structure. The jet's movement is synchronized with the evolution process of cavitating flow, effectively limiting the spread of attached cavitation, disrupting cloud integrity, and encircling scattered clouds to prevent their growth. The analysis identifies the jet's streamwise direction as critical in suppressing cavitation, with the normal direction providing supplementary support, and the spanwise direction having minimal impact. Furthermore, the jet promotes a condensation-dominant state in local flow regions, hindering cavitation growth by altering the water-vapor mass transport process.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937338","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":"Mechanical response analysis of pipeline under settlement based on pipe-soil interaction model","authors":"","doi":"10.1016/j.apor.2024.104162","DOIUrl":"10.1016/j.apor.2024.104162","url":null,"abstract":"<div><p>Long-distance pipelines have significant advantages in terms of low investment, transportation cost and high safety, which make pipeline networks expand. Pipelines inevitably pass through the collapsible loess areas in northwest China, suffering from subsidence and other disasters. To accurately analyze the effect of subsidence on the stress-strain of pipelines, the pipe-soil interaction model based on the soil constitutive model (PSIMBOSCM) was proposed to accurately obtain the soil spring performance parameters. The results of pipeline stress monitoring were numerically analyzed, and the accuracy of the model was verified. The influence of key factors such as pipe diameter, wall thickness, internal pressure, loess internal friction angle and loess moisture content on the stress-strain state of a gas pipeline under the operation were systematically studied. The results of the study showed that the finite element model of the mechanical response of buried pipeline under geological action was established and verified by in-situ monitoring data of the buried pipeline. The average relative error between the stress monitoring results and the finite element calculation results was 7.8 %. The dangerous position of the pipeline within the settlement area was located in the middle of the settlement area, and the safe settlement threshold and ultimate settlement threshold of the pipeline were 2.3 m and 3.7 m, respectively. Decreasing pipe diameter and increasing the wall thickness are effective ways to improve the bearing capacity of buried pipelines. Internal pressure has minimal influence on the mechanical response of pipelines under settlement. The loess moisture content is negatively correlated with pipeline stress, and the loess internal friction angle shows a positive correlation with pipeline stress. This research can provide valuable technical basis for the safe operation of pipelines in collapsible loess settlement areas.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141964133","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":"Vibration-based multiphase flow identification by deep learning for the vertical section of subsea pipelines","authors":"","doi":"10.1016/j.apor.2024.104167","DOIUrl":"10.1016/j.apor.2024.104167","url":null,"abstract":"<div><p>Flow pattern identification is critical for the flow assurance of the multiphase flow in the offshore oil &amp; gas industry. For this purpose, an intelligent flow pattern identification model based on a convolutional neural network (CNN) is proposed in this study to identify different flow patterns of two-phase flow in the vertical section of subsea pipelines. The different vibration signals from four vibration sensors are converted by the continuous wavelet transform (CWT), and then fed into the improved LeNet networks, where the features in the last layer of the four LeNet are fused to develop the multi-input parallel convolutional neural network (CWT-Mul-LeNet). A series of two-phase flow pattern experiments for the vertical section of subsea pipelines are implemented in the multiphase flow loop to verify the performance of the proposed model. The results show that the accuracy of the proposed CWT-Mul-LeNet model is higher than that of CWT-LeNet (a single vibration sensor is allocated). Meanwhile, the performance of CWT is better than hilbert-huang transform (HHT) and short-time Fourier transform (STFT) in terms of time-frequency conversion. In addition, the identification accuracy of 99.06 % characterized by CWT-Mul-LeNet can be further improved by introducing the convolutional block attention module (CBAM) to 99.69 %, which is explained with the 3D t-SNE algorithm by means of feature visualization. The relevant data collected from the experiment can assist in the study of pipeline flow characteristics. The constructed model integrates information from complex positions, fully compensating for the shortcomings of traditional models with a single source of information data features, and improving the accuracy of intelligent flow pattern identification.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937337","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":"Pipeline lateral buckling triggered by the residual curvature with tri-linear axial pipe-soil interaction","authors":"","doi":"10.1016/j.apor.2024.104148","DOIUrl":"10.1016/j.apor.2024.104148","url":null,"abstract":"<div><p>Unburied subsea pipelines are vulnerable to lateral buckling due to high temperature and high pressure, which can be mitigated by inducing controlled lateral buckling through introducing residual curvatures at designable positions. The axial soil resistance is crucial in controlling buckling. Thus, a tri-linear pipe-soil resistance model is incorporated into the numerical model through springs in ABAQUS to study the influence of nonlinear axial soil resistance on lateral buckling. The effect of various factors on pipeline buckling is investigated, including the model length of pipeline, axial peak soil resistance, axial peak mobilization distance, axial residual soil resistance, and axial residual mobilization distance. Results demonstrate that insufficient pipe length inhibits buckling deformation at higher temperatures, which could reduce displacement amplitude and maximum stress. Pipeline buckling is significantly affected by axial resistance. The axial peak resistance and peak mobilization distance affect both pre-buckling and post-buckling states, while axial residual resistance and residual mobilization distance mainly affect post-buckling state. Therefore, in the engineering design of pipeline buckling, it is recommended to minimize the distance between adjacent residual curvatures that trigger buckling and to carefully select an appropriate axial soil resistance model that considers the actual field conditions.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141963913","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":"Response surface method-based efficient approach for the load and resistance factors calibration of breakwater foundation considering soil spatial variability","authors":"","doi":"10.1016/j.apor.2024.104160","DOIUrl":"10.1016/j.apor.2024.104160","url":null,"abstract":"<div><p>This study aims to propose an efficient approach to calibrate the load and resistance factors (LRFs) for the limit state design of breakwater foundations. The spatial variability of soil was considered by employing the Cholesky decomposition technique. To overcome the low computational efficiency of the Monte Carlo simulation (MCS), a response surface method (RSM) was utilized. Additionally, an efficient algorithm, namely the adaptive boundary-based particle filtering algorithm (ABB-PFA), was proposed with the use of RSM to automatically and quickly search optimal nominal values of random variables in the LRF calibration process. Noticeably, the optimal number of particles and values of the modification factor used in the ABB-PFA were observed to enhance the efficiency of the calibration process. The results showed that the computational efficiency of the calibration process is significantly increased by utilizing the response surface method and the proposed ABB-PFA. The efficiency increases the most if the number of particles is one and the value of the modification factor is 0.5 or 0.6. The influences of the random field element size on the efficiency of the calibration process were also investigated. By using the appropriate size, the efficiency is significantly increased while still obtaining a high accuracy of the LRFs calibration process.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141964134","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":"Deep learning based short-term motion prediction of floating wind turbine under shutdown condition","authors":"","doi":"10.1016/j.apor.2024.104147","DOIUrl":"10.1016/j.apor.2024.104147","url":null,"abstract":"<div><p>It has become an inevitable trend for the application of the wind power generation devices to shift from land to ocean. The safety of floating offshore wind turbine (FOWT) platforms is closely related to their motion response. The motion response of platforms will be affected by various factors, such as waves, wind, and currents. Predicting the short-term motion response of a platform with high precision and utilizing the predicted values for advanced control has always been a significant concern. At present, the development of deep learning technology has brought some potential solutions to this problem. In this paper, we proposed a method combining convolutional neural network (CNN) and gated recurrent unit (GRU) to predict the short-term motion response of the platform. Specifically, a series of numerical simulation of the 5MW OC4 semi-submersible FOWT under shutdown conditions are carried out, and the wave elevation and platform motion data are obtained based on the simulation data. The simulation data is then divided into the training set, validation set and test set. In this paper, we combine the Bayesian optimization algorithm to adaptively select the optimal hyper-parameters of the deep learning model and use the optimal hyper-parameters to establish the optimal CNN-GRU model for training. By comparing the prediction results of GRU, long short-term memory (LSTM), CNN, and CNN-LSTM models, we found that the CNN-GRU hybrid model achieves the highest prediction accuracy on different datasets. More importantly, when comparing the prediction results with the real values, it is found that the CNN-GRU hybrid model has strong non-linear expression ability for prediction duration of 2 s, 4 s, 6 s, and 8 s. The prediction accuracy is negatively correlated with the prediction duration. Finally, it is proved that the CNN-GRU model has significant advantages in terms of prediction accuracy and training time. We verify the CNN-GRU model using the dataset under combined wind-wave action, proving that the model is transferable and suitable for complex working conditions. This provides an idea for optimizing the motion response prediction model of FOWT.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937280","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 modelling of copper alloy aquaculture net in currents with the Smoothed Particle Hydrodynamics method.","authors":"","doi":"10.1016/j.apor.2024.104151","DOIUrl":"10.1016/j.apor.2024.104151","url":null,"abstract":"<div><p>Aquaculture in high-energy areas poses significant challenges to traditional engineering tools, as the strong non-linear loads exerted on structures often require more refined numerical models. In this work, we carry out the numerical modelling of an aquaculture net made of copper alloy interacting with current, employing a Computational Fluid Dynamic (CFD) method. The numerical approach used in this work allows for the simulation of the direct interaction between the net and the fluid, without the need to use hydrodynamic coefficients to model the net, unlike traditional numerical approaches. The methodology used was validated at current velocities typical of high energy sea states and gave satisfactory results in the majority of cases analysed. The methodology presented here allows the evaluation of hydrodynamic forces on the numerical net, its displacement and deformation, and the fluid velocity field surrounding the net. The proposed methodology is based on the application of the Smoothed Particle Hydrodynamics (SPH) method. The net is modelled as a set of fluid-driven elements with spherical geometry connected with dynamic mooring lines, where the boundary particles that make up the fluid-driven elements interact with the particles that make up the fluid, providing the fluid-structure interaction. The numerical modelling of the net is executed through the coupling of DualSPHysics and MoorDyn+. DualSPHysics is an open-source, fully Lagrangian, meshless code based on weakly compressible SPH that addresses the fluid-structure interaction. On the other hand, MoorDyn+ is a dynamic mooring library that uses a lumped-mass numerical model to resolve tensions in the mooring lines and allows the connections between fluid-driven elements. Two cases of analysis were carried out and validated against experimental data. For the first case, the net was modelled in a fixed frame in currents and the drag forces on the net were evaluated. In the second case, the setup comprises a floating fish cage (scale 1:15) with a copper alloy net moored to a fixed point, modelled in currents. In this latest study, the loads on the fish cage measured at the mooring were evaluated. The numerical results showed a satisfactory agreement.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0141118724002724/pdfft?md5=e8996355c990fe17b79fdf4eeac9bb20&pid=1-s2.0-S0141118724002724-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937341","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":"Performance prediction of a hydrofoil near the free surface using low (BEM) and high (RANS) fidelity methods","authors":"","doi":"10.1016/j.apor.2024.104157","DOIUrl":"10.1016/j.apor.2024.104157","url":null,"abstract":"<div><p>As a first step toward a multi-fidelity optimization tool for hydrofoils, the present work assesses the ability of the in-house code PUFFIn to be used as a “low-fidelity” solver within the multi-fidelity framework. The code, based on the Boundary Element Method (BEM) and the potential flow theory, is used to study the performance of a typical windsurf hydrofoil operating near the free surface. The hydrofoil is composed of a front wing and a rear stabilizer in a plane-like configuration. Computations are performed for single body configurations (only one wing) and two-body configurations (front wing and stabilizer). First, three linearized models of the free surface are compared for the single front wing configuration with several values of the Froude number: the symmetry, anti-symmetry and Neumann-Kelvin conditions. The results show that for relatively high Froude number, the anti-symmetry and the Neumann-Kelvin conditions provide very similar forces. Then, the predictions of the BEM solver are compared with “high-fidelity” RANS computations, in terms of pressure drag and lift, pressure distribution on the hydrofoil and free surface elevation. Several Froude numbers and submergence depths are studied. The global lift and drag variations predicted by the BEM with the anti-symmetry and Neumann-Kelvin conditions on the single-body configurations are similar to the RANS predictions. For the two-body configurations, the Neumann-Kelvin condition outperforms the anti-symmetry condition. Based on the BEM/RANS comparison, the potential flow solver reveals to be a relevant tool for multi-fidelity optimization.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937340","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":"Development of a novel multi-component coupled numerical model for aquaculture systems in OpenFOAM","authors":"","doi":"10.1016/j.apor.2024.104146","DOIUrl":"10.1016/j.apor.2024.104146","url":null,"abstract":"<div><p>The motion and deformation of an aquaculture system under wave and current conditions is a complex fluid–structure interactions problem. Existing models often lack the capability to accurately simulate these interactions across all components of an aquaculture system. To address this limitation, we have developed a novel multi-component numerical model that coupled high-fidelity flow simulations in OpenFOAM freeware, and structural dynamics in MoorDyn, and EndoBeams modules. Our integrated model employs an incompressible fluid solver with a Volume of Fluid (VOF) method to capture multiphase fluid dynamics, while a screen model and mass spring method account for the flexible nets deformation. MoorDyn is used for simulating mooring line dynamics, and EndoBeams solves structural deformation of components such as collars and frames. The Immersed Boundary Method (IBM) is used to capture the interaction between the fluid and the structural components. By updating the deformation and motion states and exchanging positions and forces in each time step, the model ensures effective coupling between different components. Extensive validation against published experimental data confirms that our model is a robust tool for simulating the interactions of aquaculture systems with fluid and between all components, providing valuable insights for their design and optimization.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0141118724002670/pdfft?md5=5b2c997ddeb900911c6857ea28b0869f&pid=1-s2.0-S0141118724002670-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937342","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 study on wave attenuation and stability of ecological dike system composed of submerged breakwater, mangrove, and dike under storm surge","authors":"","doi":"10.1016/j.apor.2024.104144","DOIUrl":"10.1016/j.apor.2024.104144","url":null,"abstract":"<div><p>Four tests were conducted to investigate the wave attenuation and dike stability effectiveness of a basic dike, a dike that combined with the submerged breakwater, with mangrove, and with both submerged breakwater and mangrove. Wave variation, hydrodynamic responses (wave scour, wave pressure, pore pressure), and dike stability were investigated. It was found that the submerged breakwater effectively reduced wave height and wave pressure in small wave conditions. However, the dike stability was not improved due to the balance between the positive effect of wave attenuation and the negative effect of water elevation increase in large wave conditions. The mangrove's wave attenuation effects were remarkable at both small and large wave conditions, leading to smaller hydrodynamic responses and ultimately contributing to a significant improvement in the dike stability. The combination of submerged breakwater and mangrove induced the best wave attenuation effect in shallow water with the smallest hydrodynamic responses. However, the presence of submerged breakwater amplified water elevation and significant wave height in deep water conditions, inducing stronger wave impact and more intense wave scour, ultimately resulting in the weaker stability of the dike.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937365","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}