High-speed craft generally applies hy droplane boat-type and large power engine to obtain high speed in water as results that significant hydrodynamic nonlinearities, high-speed craft has complex the impact load characteristics and structural response which attract considerable attentions of ship mechanics researchers. This paper studies impacting load and structural response of a high-speed craft by means of numerical approach coupling CFD and FEM. A model experiment of high-speed craft is selected to simulate impact load and structural response, the craft model consists of two ship bodies and a keel beam, a number of pressure sensors and strain gauges are arranged to capture the impacting pres s ure and VBM. A numerical FSI approach coupling CFD and FEM is used to study the model experiment of the high-speed craft. CFD is used to solve the hydrodynamics of the high-speed craft, DFBI and overset grid algorithm are employed to simulate the craft motion. Dy namic FEM is us ed to calculate structural response of high-speed craft, structural VBM is obtained. Two-way FSI is employ ed to realize coupling of CFD and FEM, wave pres s ures and structural displacement are iterated to progress. At last, numerical res ults and experimental res ults including impacting pressure, craft motion and VBM are compared and analyzed, they agree with closely. The numerical approach can be used to study the impacting load and structural respons e for high-speed craft.
高速船一般采用斜面船型和大功率发动机在水中获得较高的速度，由于显著的水动力非线性，高速船具有复杂的冲击载荷特性和结构响应，这引起了船舶力学研究人员的极大关注。本文通过将 CFD 和 FEM 相结合的数值方法研究了高速船的冲击载荷和结构响应。选取高速船模型试验来模拟冲击载荷和结构响应，船模由两个船体和一个龙骨梁组成，布置了多个压力传感器和应变片来捕捉冲击预态和 VBM。采用 CFD 和 FEM 相结合的 FSI 数值方法来研究高速船的模型试验。CFD 用于求解高速飞行器的流体力学，DFBI 和超集网格算法用于模拟飞行器的运动。利用动态有限元计算高速飞行器的结构响应，得到结构 VBM。采用双向 FSI 实现 CFD 与 FEM 的耦合，对波浪预报和结构位移进行迭代。最后，将数值结果与实验结果（包括冲击压力、飞艇运动和 VBM）进行对比分析，结果非常吻合。该数值方法可用于研究高速飞行器的冲击载荷和结构响应。
{"title":"Numerical Research on Impacting Load and Structural Response for a Model Experiment of High-speed Craft","authors":"Weiqin Liu, Yuxin Qin, Yuchen Hu, Nikola Vladimir, Shuangxi Xu, Yigang Wu","doi":"10.1115/1.4065153","DOIUrl":"https://doi.org/10.1115/1.4065153","url":null,"abstract":"\u0000 High-speed craft generally applies hy droplane boat-type and large power engine to obtain high speed in water as results that significant hydrodynamic nonlinearities, high-speed craft has complex the impact load characteristics and structural response which attract considerable attentions of ship mechanics researchers. This paper studies impacting load and structural response of a high-speed craft by means of numerical approach coupling CFD and FEM. A model experiment of high-speed craft is selected to simulate impact load and structural response, the craft model consists of two ship bodies and a keel beam, a number of pressure sensors and strain gauges are arranged to capture the impacting pres s ure and VBM. A numerical FSI approach coupling CFD and FEM is used to study the model experiment of the high-speed craft. CFD is used to solve the hydrodynamics of the high-speed craft, DFBI and overset grid algorithm are employed to simulate the craft motion. Dy namic FEM is us ed to calculate structural response of high-speed craft, structural VBM is obtained. Two-way FSI is employ ed to realize coupling of CFD and FEM, wave pres s ures and structural displacement are iterated to progress. At last, numerical res ults and experimental res ults including impacting pressure, craft motion and VBM are compared and analyzed, they agree with closely. The numerical approach can be used to study the impacting load and structural respons e for high-speed craft.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140217071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Unsteady Reynolds averaged Navier-Stokes (RANS) method combined with Spalart-Allmaras turbulence model and dynamic mesh technology were used to investigate the impact of wake vortex on the vibration response of a cylinder. By analyzing the phase difference between the wake vortex force and the displacement under different mass parameters in flow-induced vibration (FIV), the study reveals that the influence of wake vortex on the cylinder varies significantly in different vibration branches. The wake vortex of the initial branch enhances the cylinder's vibration, whereas the wake vortices of the upper, lower, and desynchronized branches suppress the vibration. At the critical point between the initial branch and the upper branch of vortex induced vibration (VIV), there is a 90° phase jump, and the instantaneous phase difference fluctuation between the wake vortex force and displacement of the VIV branch remains relatively constant. In the galloping branch, there are wake vortices in different directions that affect the cylinder's vibration every quarter of the vibration period, and the phase difference undergoes periodic large fluctuations (either in-phase or out-of-phase), with the result that the wake vortex force periodically promotes or restrain the cylinder's vibration, which can serve as a novel criterion for identifying the occurrence of galloping. Furthermore, when varying the mass parameters at a constant reduced velocity, the impact of the wake vortex in the initial branch is relatively insignificant. However, as the mass ratio increases in other vibration branches, the suppressive effect increases, and the wake vortex force can prevent VIV induced galloping phenomenon by affecting the vibration intensity.
{"title":"Mechanism analysis of the effect of wake vortex on cylinder vibration in flow induced motion","authors":"Dahai Zhang, Hao Yang, Shuai Zhang","doi":"10.1115/1.4065101","DOIUrl":"https://doi.org/10.1115/1.4065101","url":null,"abstract":"\u0000 Unsteady Reynolds averaged Navier-Stokes (RANS) method combined with Spalart-Allmaras turbulence model and dynamic mesh technology were used to investigate the impact of wake vortex on the vibration response of a cylinder. By analyzing the phase difference between the wake vortex force and the displacement under different mass parameters in flow-induced vibration (FIV), the study reveals that the influence of wake vortex on the cylinder varies significantly in different vibration branches. The wake vortex of the initial branch enhances the cylinder's vibration, whereas the wake vortices of the upper, lower, and desynchronized branches suppress the vibration. At the critical point between the initial branch and the upper branch of vortex induced vibration (VIV), there is a 90° phase jump, and the instantaneous phase difference fluctuation between the wake vortex force and displacement of the VIV branch remains relatively constant. In the galloping branch, there are wake vortices in different directions that affect the cylinder's vibration every quarter of the vibration period, and the phase difference undergoes periodic large fluctuations (either in-phase or out-of-phase), with the result that the wake vortex force periodically promotes or restrain the cylinder's vibration, which can serve as a novel criterion for identifying the occurrence of galloping. Furthermore, when varying the mass parameters at a constant reduced velocity, the impact of the wake vortex in the initial branch is relatively insignificant. However, as the mass ratio increases in other vibration branches, the suppressive effect increases, and the wake vortex force can prevent VIV induced galloping phenomenon by affecting the vibration intensity.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140232003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gaussian process regression (GPR) is a commonly used approach for establishing the nonparametric models of ship maneuvering motion, and its performance depends on the selection of the kernel function. However, no single kernel function can be universally applied to all nonparametric models of ship maneuvering motion, which may compromise the robustness of GPR. To address this issue, an adaptive ensemble of multi-kernel GPRs based on heuristic model screening (AEGPR-HMS) is proposed in this paper. In the proposed method, four kernel functions are involved in constructing the ensemble model. The HMS method is introduced to determine the weights of individual-based GPR models, which can be adaptively assigned according to the baseline GPR model. To determine the hyper-parameters of these kernel functions, the genetic algorithm is also employed to compute the optimal values. The KVLCC2 tanker provided by the SIMMAN 2008 workshop is used to validate the performance of the proposed method. The results demonstrate that the AEGPR-HMS is an efficient and robust method for nonparametric modeling of ship maneuvering motion.
{"title":"Adaptive Ensemble of Multi-kernel Gaussian Process Regressions based on Heuristic Model Screening for Nonparametric Modeling of Ship Maneuvering Motion","authors":"Lichao Jiang, Xiaobing Shang, Xinyu Qi, Zilu Ouyang, Zhi Zhang","doi":"10.1115/1.4064856","DOIUrl":"https://doi.org/10.1115/1.4064856","url":null,"abstract":"\u0000 Gaussian process regression (GPR) is a commonly used approach for establishing the nonparametric models of ship maneuvering motion, and its performance depends on the selection of the kernel function. However, no single kernel function can be universally applied to all nonparametric models of ship maneuvering motion, which may compromise the robustness of GPR. To address this issue, an adaptive ensemble of multi-kernel GPRs based on heuristic model screening (AEGPR-HMS) is proposed in this paper. In the proposed method, four kernel functions are involved in constructing the ensemble model. The HMS method is introduced to determine the weights of individual-based GPR models, which can be adaptively assigned according to the baseline GPR model. To determine the hyper-parameters of these kernel functions, the genetic algorithm is also employed to compute the optimal values. The KVLCC2 tanker provided by the SIMMAN 2008 workshop is used to validate the performance of the proposed method. The results demonstrate that the AEGPR-HMS is an efficient and robust method for nonparametric modeling of ship maneuvering motion.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140425304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chain link fatigue failures in mooring lines have recently aroused the interest of the technical community in developing new design and monitoring methodologies focused on considering the effects of local corrosion. Experimental breakage test results evidenced that the effects of mean tension, pitting corrosion and surface roughness may influence the fatigue strength of chain links. A recently-developed methodology here denoted as Corrosion Grade considers the effects of mean tension and local corrosion through a visual assessment of the chain. The present work proposes a parametric correction factor to be used in the current S-N fatigue design methodology for considering local corrosion in studless chains. The parametric model is developed by means of finite element-based modeling of various pit shapes in the chain. The correction factor is fitted as a function of the pit aspect ratio. The proposed correction factor is combined with the Corrosion Grade methodology to obtain a final formula that considers the mean tension and the local corrosion. Results from both Corrosion Grade and the proposed correction factor are compared in three corroded experimental test samples. The proposed correction factor is capable of estimating the fatigue life of the corroded components analyzed with conservatism.
{"title":"A Practical Procedure for Fatigue Assessment of Mooring Line Chains with Pitting Corrosion","authors":"Filipe A. Rezende, P. Videiro, L. Sagrilo","doi":"10.1115/1.4064855","DOIUrl":"https://doi.org/10.1115/1.4064855","url":null,"abstract":"\u0000 Chain link fatigue failures in mooring lines have recently aroused the interest of the technical community in developing new design and monitoring methodologies focused on considering the effects of local corrosion. Experimental breakage test results evidenced that the effects of mean tension, pitting corrosion and surface roughness may influence the fatigue strength of chain links. A recently-developed methodology here denoted as Corrosion Grade considers the effects of mean tension and local corrosion through a visual assessment of the chain. The present work proposes a parametric correction factor to be used in the current S-N fatigue design methodology for considering local corrosion in studless chains. The parametric model is developed by means of finite element-based modeling of various pit shapes in the chain. The correction factor is fitted as a function of the pit aspect ratio. The proposed correction factor is combined with the Corrosion Grade methodology to obtain a final formula that considers the mean tension and the local corrosion. Results from both Corrosion Grade and the proposed correction factor are compared in three corroded experimental test samples. The proposed correction factor is capable of estimating the fatigue life of the corroded components analyzed with conservatism.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140427789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Mathias, Caio Fabricio Deberaldini Netto, Felipe Marino Moreno, Jefferson Fialho Coelho, Lucas Palmiro de Freitas, Marcel Rodrigues de Barros, Pedro C. Mello, Marcelo Dottori, F. G. Cozman, Anna Helena Reali Costa, Alberto Costa Nogueira Junior, E. Gomi, E. Tannuri
We develop and implement a Neural Operator (NOp) to predict the evolution of waves on the surface of water. The NOp uses a Graph Neural Network (GNN) to connect randomly sampled points on the water surface and exchange information between them to make the prediction. Our main contribution is adding physical knowledge to the implementation, which allows the model to be more general and able to be used in domains of different geometries with no retraining. Our implementation also takes advantage of the fact that the governing equations are independent of rotation and translation to make training easier. In this work, the model is trained with data from a single domain with fixed dimensions and evaluated in domains of different dimensions with little impact to performance.
{"title":"A PHYSICS-INFORMED NEURAL OPERATOR FOR THE SIMULATION OF SURFACE WAVES","authors":"M. Mathias, Caio Fabricio Deberaldini Netto, Felipe Marino Moreno, Jefferson Fialho Coelho, Lucas Palmiro de Freitas, Marcel Rodrigues de Barros, Pedro C. Mello, Marcelo Dottori, F. G. Cozman, Anna Helena Reali Costa, Alberto Costa Nogueira Junior, E. Gomi, E. Tannuri","doi":"10.1115/1.4064676","DOIUrl":"https://doi.org/10.1115/1.4064676","url":null,"abstract":"\u0000 We develop and implement a Neural Operator (NOp) to predict the evolution of waves on the surface of water. The NOp uses a Graph Neural Network (GNN) to connect randomly sampled points on the water surface and exchange information between them to make the prediction. Our main contribution is adding physical knowledge to the implementation, which allows the model to be more general and able to be used in domains of different geometries with no retraining. Our implementation also takes advantage of the fact that the governing equations are independent of rotation and translation to make training easier. In this work, the model is trained with data from a single domain with fixed dimensions and evaluated in domains of different dimensions with little impact to performance.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139798975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Mathias, Caio Fabricio Deberaldini Netto, Felipe Marino Moreno, Jefferson Fialho Coelho, Lucas Palmiro de Freitas, Marcel Rodrigues de Barros, Pedro C. Mello, Marcelo Dottori, F. G. Cozman, Anna Helena Reali Costa, Alberto Costa Nogueira Junior, E. Gomi, E. Tannuri
We develop and implement a Neural Operator (NOp) to predict the evolution of waves on the surface of water. The NOp uses a Graph Neural Network (GNN) to connect randomly sampled points on the water surface and exchange information between them to make the prediction. Our main contribution is adding physical knowledge to the implementation, which allows the model to be more general and able to be used in domains of different geometries with no retraining. Our implementation also takes advantage of the fact that the governing equations are independent of rotation and translation to make training easier. In this work, the model is trained with data from a single domain with fixed dimensions and evaluated in domains of different dimensions with little impact to performance.
{"title":"A PHYSICS-INFORMED NEURAL OPERATOR FOR THE SIMULATION OF SURFACE WAVES","authors":"M. Mathias, Caio Fabricio Deberaldini Netto, Felipe Marino Moreno, Jefferson Fialho Coelho, Lucas Palmiro de Freitas, Marcel Rodrigues de Barros, Pedro C. Mello, Marcelo Dottori, F. G. Cozman, Anna Helena Reali Costa, Alberto Costa Nogueira Junior, E. Gomi, E. Tannuri","doi":"10.1115/1.4064676","DOIUrl":"https://doi.org/10.1115/1.4064676","url":null,"abstract":"\u0000 We develop and implement a Neural Operator (NOp) to predict the evolution of waves on the surface of water. The NOp uses a Graph Neural Network (GNN) to connect randomly sampled points on the water surface and exchange information between them to make the prediction. Our main contribution is adding physical knowledge to the implementation, which allows the model to be more general and able to be used in domains of different geometries with no retraining. Our implementation also takes advantage of the fact that the governing equations are independent of rotation and translation to make training easier. In this work, the model is trained with data from a single domain with fixed dimensions and evaluated in domains of different dimensions with little impact to performance.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139858905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most models employed for fluid forces in drill-string dynamics are of reduced order. The simplified nature of these models often fails to describe complex behaviour of the fluid force, in particular when the drill-string movement is non-trivial or even when non-Newtonian behaviour is predominant. In this work, the fluid forces are estimated by modelling the dynamic of the drilling fluid for both Newtonian and non-Newtonian fluids, and compared with reduced order models. To achieve it, the lattice Boltzmann method is implemented to solve the fluid model, while prescribed movements are set for the tool-joint. With the obtained fields, the forces are calculated and compared with recurrent models. Finally, it is observed that some models are capable of describing the interaction as long as the dynamic of the tool-joint is simple. In the presence of other trajectories – e.g.: bouncing and chaotic – the models fail to describe the details of the dynamic.
{"title":"A COUPLED FLUID-STRUCTURE MODEL FOR ESTIMATION OF HYDRAULIC FORCES ON THE DRILL-PIPES","authors":"L. Volpi, E. Cayeux, R. W. Time","doi":"10.1115/1.4064614","DOIUrl":"https://doi.org/10.1115/1.4064614","url":null,"abstract":"\u0000 Most models employed for fluid forces in drill-string dynamics are of reduced order. The simplified nature of these models often fails to describe complex behaviour of the fluid force, in particular when the drill-string movement is non-trivial or even when non-Newtonian behaviour is predominant. In this work, the fluid forces are estimated by modelling the dynamic of the drilling fluid for both Newtonian and non-Newtonian fluids, and compared with reduced order models. To achieve it, the lattice Boltzmann method is implemented to solve the fluid model, while prescribed movements are set for the tool-joint. With the obtained fields, the forces are calculated and compared with recurrent models. Finally, it is observed that some models are capable of describing the interaction as long as the dynamic of the tool-joint is simple. In the presence of other trajectories – e.g.: bouncing and chaotic – the models fail to describe the details of the dynamic.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140481661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Suction anchors are large cylindrical anchors and well-suited for both catenary and taut mooring systems. The determination of horizontal and vertical load components hinges upon factors such as inclined loading angle and the padeye position, significantly influencing its failure mechanism. This study undertook a series of geotechnical centrifuge tests to scrutinize the behavior of suction anchor under lateral loading. Precise measurements were taken for variables including the pore pressure at the anchor tip, soil pressure along the anchor, anchor capacity, as well as the displacement and rotation around X, Y, and Z axes. The anchor failure mechanisms and interaction coefficients within a dissipation function were determined from the experimental results. The failure angle β serves as an indicator of anchor rotation in the translational failure mechanism, and αr describes anchor rotation in backward and forward movements. Under the inclined loading angle (θm) of 35°, the anchor failed in translational mechanism, with its ultimate bearing capacity surpassing that of the anchor failing through backward and forward mechanisms. Upon elevating the padeye location moved upward to 4L/7 to 2L/3, the anchor failed in a forward mechanism, accompanied by a significant decrease in soil pressure in the passive side. This separation of the soil plug from the anchor, driven by accumulated displacement and rotation, resulted in 25% decrease in ultimate bearing capacity. Conversely, when the inclined loading reduced from 35° to 20° at padeye location, the anchor failed in a backward mechanism, with no observed separation of the soil plug from the anchor.
{"title":"Centrifuge modelling of the performance of suction anchor in soft clay","authors":"Dongkang Fu, Ying Lai, Xiong Gen, Bin Zhu","doi":"10.1115/1.4064617","DOIUrl":"https://doi.org/10.1115/1.4064617","url":null,"abstract":"\u0000 Suction anchors are large cylindrical anchors and well-suited for both catenary and taut mooring systems. The determination of horizontal and vertical load components hinges upon factors such as inclined loading angle and the padeye position, significantly influencing its failure mechanism. This study undertook a series of geotechnical centrifuge tests to scrutinize the behavior of suction anchor under lateral loading. Precise measurements were taken for variables including the pore pressure at the anchor tip, soil pressure along the anchor, anchor capacity, as well as the displacement and rotation around X, Y, and Z axes. The anchor failure mechanisms and interaction coefficients within a dissipation function were determined from the experimental results. The failure angle β serves as an indicator of anchor rotation in the translational failure mechanism, and αr describes anchor rotation in backward and forward movements. Under the inclined loading angle (θm) of 35°, the anchor failed in translational mechanism, with its ultimate bearing capacity surpassing that of the anchor failing through backward and forward mechanisms. Upon elevating the padeye location moved upward to 4L/7 to 2L/3, the anchor failed in a forward mechanism, accompanied by a significant decrease in soil pressure in the passive side. This separation of the soil plug from the anchor, driven by accumulated displacement and rotation, resulted in 25% decrease in ultimate bearing capacity. Conversely, when the inclined loading reduced from 35° to 20° at padeye location, the anchor failed in a backward mechanism, with no observed separation of the soil plug from the anchor.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140485622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper proposes a shore-based constant tension mooring system, which improves the cable tension distribution by adjusting the length of the cable to maintain the constant tension of the cable between the ship and the mooring pile, in order to solve the problem of poor safety and reliability of the traditional mooring system in the mooring process. Firstly, based on the three-dimensional potential flow theory, this paper uses the hydrodynamic software AQWA to numerically simulate the dynamic response of the traditional mooring system under the coupling of wind, wave, and current in different sea states. Subsequently, a shore-based constant tension mooring system using the principle of volume-varying hydraulic control was studied. On the basis of a comprehensive analysis of the working principle of the constant tension hydraulic control mooring system, a mathematical model of the main working circuit is established. The system was numerically simulated by relying on MATLAB/simulink simulation software. Finally, by comparing with traditional mooring systems, the results show that the maximum cable tension of the shore-based constant-tension mooring system is significantly reduced, so that the tension is controlled within a fixed range, and the safety factor of the mooring cable is significantly improved, thus reducing the risk of mooring system failure and improving the ship's survivability.
{"title":"Study on cable tension characteristics of shore-based constant tension mooring systems under the coupling effect of wind, wave, and current","authors":"Li Wang, Nan Liu, Shoujun Wang, Songgui Chen","doi":"10.1115/1.4064615","DOIUrl":"https://doi.org/10.1115/1.4064615","url":null,"abstract":"\u0000 This paper proposes a shore-based constant tension mooring system, which improves the cable tension distribution by adjusting the length of the cable to maintain the constant tension of the cable between the ship and the mooring pile, in order to solve the problem of poor safety and reliability of the traditional mooring system in the mooring process. Firstly, based on the three-dimensional potential flow theory, this paper uses the hydrodynamic software AQWA to numerically simulate the dynamic response of the traditional mooring system under the coupling of wind, wave, and current in different sea states. Subsequently, a shore-based constant tension mooring system using the principle of volume-varying hydraulic control was studied. On the basis of a comprehensive analysis of the working principle of the constant tension hydraulic control mooring system, a mathematical model of the main working circuit is established. The system was numerically simulated by relying on MATLAB/simulink simulation software. Finally, by comparing with traditional mooring systems, the results show that the maximum cable tension of the shore-based constant-tension mooring system is significantly reduced, so that the tension is controlled within a fixed range, and the safety factor of the mooring cable is significantly improved, thus reducing the risk of mooring system failure and improving the ship's survivability.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140483186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The oscillating water column (OWC) is an economical and feasible type of wave energy converter with minimal maintenance costs which have been widely investigated. In this study, the effect of lipwalls for a shore-front OWC is investigated using Dual Boundary Equation Method (DBEM) and Computational Fluid Dynamics (CFD) approaches. The boundary value problem is solved using the DBEM method within the framework of linear water wave theory. Whilst in the CFD approach, the volume of fluid (VOF) approach is used for simulating the numerical wave tank, with appropriate boundary conditions and regular wave inlet. The DBEM approach is beneficial to understand the complex phenomena inside the chamber viz. radiation conductance and susceptance. It is inferred that case-B is found to exhibit better performance for a wider range of non-dimensional wave frequencies due to its wave trapping configuration where the position of the lower lipwall is orthogonal. The CFD studies provide interesting insights on the optimal damping ratio concerning wave amplification factor at higher relative water depths, power output, and correlation of phase difference. Besides, the study reveals that the pressure and wave elevation inside the chamber is associated with the inhalation and exhalation process of air is attributed to the lower half of the lipwall.
{"title":"Lipwall effects on a Shore-Front Oscillating Water Column (OWC) based on DBEM and CFD approaches","authors":"Kumar Narendran, Vijay K G","doi":"10.1115/1.4064616","DOIUrl":"https://doi.org/10.1115/1.4064616","url":null,"abstract":"\u0000 The oscillating water column (OWC) is an economical and feasible type of wave energy converter with minimal maintenance costs which have been widely investigated. In this study, the effect of lipwalls for a shore-front OWC is investigated using Dual Boundary Equation Method (DBEM) and Computational Fluid Dynamics (CFD) approaches. The boundary value problem is solved using the DBEM method within the framework of linear water wave theory. Whilst in the CFD approach, the volume of fluid (VOF) approach is used for simulating the numerical wave tank, with appropriate boundary conditions and regular wave inlet. The DBEM approach is beneficial to understand the complex phenomena inside the chamber viz. radiation conductance and susceptance. It is inferred that case-B is found to exhibit better performance for a wider range of non-dimensional wave frequencies due to its wave trapping configuration where the position of the lower lipwall is orthogonal. The CFD studies provide interesting insights on the optimal damping ratio concerning wave amplification factor at higher relative water depths, power output, and correlation of phase difference. Besides, the study reveals that the pressure and wave elevation inside the chamber is associated with the inhalation and exhalation process of air is attributed to the lower half of the lipwall.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140481670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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