Guo H. Dong, Yanjun Mao, Yufei Wu, Xiaozhou Ma, Yuan Fang, Xiong Lu, Luyao Zhang, Diwen Zhou, Zhiqiang Liu
A flexibly connected double-module floating structure can be used as the primary component unit of a large multi-module floating structure, revealing some basic principles regarding the interaction of multiple modules and connectors to the same extent. This study investigated the hydrodynamic characteristics of a double-module floating structure with cable-fender connectors and connector loads through an experimental model test. Owing to the flexible connector's weak coupling strength, the two modules' motion responses in the double-module floating structure are similar to those of the single-module floating structure. The magnitude of the connector load is related to the relative pitch motion of the two modules. The increased stiffness of the connector can limit the pitch motion of the modules but can also lead to higher forces on the connector. The load acting on the fender in the cable-fender connector is strongly nonlinear, and the shear force on the fender due to the deflection load is large; this may be the controlling load causing fender damage.
{"title":"Experimental study on the hydrodynamic performance of a flexible connected double-module floating structure","authors":"Guo H. Dong, Yanjun Mao, Yufei Wu, Xiaozhou Ma, Yuan Fang, Xiong Lu, Luyao Zhang, Diwen Zhou, Zhiqiang Liu","doi":"10.1115/1.4064537","DOIUrl":"https://doi.org/10.1115/1.4064537","url":null,"abstract":"\u0000 A flexibly connected double-module floating structure can be used as the primary component unit of a large multi-module floating structure, revealing some basic principles regarding the interaction of multiple modules and connectors to the same extent. This study investigated the hydrodynamic characteristics of a double-module floating structure with cable-fender connectors and connector loads through an experimental model test. Owing to the flexible connector's weak coupling strength, the two modules' motion responses in the double-module floating structure are similar to those of the single-module floating structure. The magnitude of the connector load is related to the relative pitch motion of the two modules. The increased stiffness of the connector can limit the pitch motion of the modules but can also lead to higher forces on the connector. The load acting on the fender in the cable-fender connector is strongly nonlinear, and the shear force on the fender due to the deflection load is large; this may be the controlling load causing fender damage.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139604688","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 deformation caused by waves and current in an aquatic environment significantly impacts the remaining volume of a net cage. Its fluctuations in magnitude could pose a potential threat to the well-being of cultivated species. There's a critical need for a simple, cost-effective solution to monitor cage deformation in real-time. This study proposes a depth-based method, utilizing just two depth meters attached to the cage's floating collar and tube sinker, to estimate the remaining volume. Comparing to the experimental measurements from previous studies, this method demonstrates satisfactory accuracies. Under current-only and waves-current conditions, the estimation differences are around 11.6% and 23%, respectively. In contrast, when compared to commonly-used volume-based methods, the differences are approximately 1.8% and 9.5%. Despite a tendency for overestimation when the mean cross-sectional area deviates from the original top or bottom area of the cage, this method remains a feasible alternative. Its practicality highlights its potential as an efficient means of monitoring cage deformation.
{"title":"Numerical simulation of net cage and an alternative method to estimate the remaining volume","authors":"H. Tang, Po-Hung Yeh, Ray-Yeng Yang, Fan-Hua Nan","doi":"10.1115/1.4064538","DOIUrl":"https://doi.org/10.1115/1.4064538","url":null,"abstract":"\u0000 The deformation caused by waves and current in an aquatic environment significantly impacts the remaining volume of a net cage. Its fluctuations in magnitude could pose a potential threat to the well-being of cultivated species. There's a critical need for a simple, cost-effective solution to monitor cage deformation in real-time. This study proposes a depth-based method, utilizing just two depth meters attached to the cage's floating collar and tube sinker, to estimate the remaining volume. Comparing to the experimental measurements from previous studies, this method demonstrates satisfactory accuracies. Under current-only and waves-current conditions, the estimation differences are around 11.6% and 23%, respectively. In contrast, when compared to commonly-used volume-based methods, the differences are approximately 1.8% and 9.5%. Despite a tendency for overestimation when the mean cross-sectional area deviates from the original top or bottom area of the cage, this method remains a feasible alternative. Its practicality highlights its potential as an efficient means of monitoring cage deformation.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139603628","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}
Duppala Azad, Sunny Kumar Annam, V. R. Menda, P. Swain, Srinivas Vadapalli, Divakar Bommana
The development of propulsion devices by using the propulsive mechanisms of aquatic animals such as fish is a challenging task. An attempt has been made to replicate the fishtailed motion that caused thrust in the current investigation. At a low Reynolds number of Re = 1173, the propulsive performance of NACA (National Advisory Committee for Aeronautics) 0012 flapping foils enduring distinct flapping trajectories (fishtailed and elliptical) is evaluated. A dynamic mesh arbitrary Lagrangian-Eulerian framework is used to understand the desired flapping motion of the foils while solving the flow via in-compressible Navier-Stokes equations. Along with the flapping trajectory, the effects of the Strouhal number (St), inter-foils distance (Lx), and phase angle (φ) between the foils on the produced thrust are examined. The results demonstrate that using tandem configuration flapping foil with elliptical and fishtailed flapping can significantly increase the induced thrust and propulsive efficiency.
{"title":"The impact of flapping trajectories on the induced thrust of a Single and tandem configuration flapping foil","authors":"Duppala Azad, Sunny Kumar Annam, V. R. Menda, P. Swain, Srinivas Vadapalli, Divakar Bommana","doi":"10.1115/1.4064500","DOIUrl":"https://doi.org/10.1115/1.4064500","url":null,"abstract":"\u0000 The development of propulsion devices by using the propulsive mechanisms of aquatic animals such as fish is a challenging task. An attempt has been made to replicate the fishtailed motion that caused thrust in the current investigation. At a low Reynolds number of Re = 1173, the propulsive performance of NACA (National Advisory Committee for Aeronautics) 0012 flapping foils enduring distinct flapping trajectories (fishtailed and elliptical) is evaluated. A dynamic mesh arbitrary Lagrangian-Eulerian framework is used to understand the desired flapping motion of the foils while solving the flow via in-compressible Navier-Stokes equations. Along with the flapping trajectory, the effects of the Strouhal number (St), inter-foils distance (Lx), and phase angle (φ) between the foils on the produced thrust are examined. The results demonstrate that using tandem configuration flapping foil with elliptical and fishtailed flapping can significantly increase the induced thrust and propulsive efficiency.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139528239","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}
Erik Vanem, E. Fekhari, Nikolay K. Dimitrov, Mark Kelly, Alexis Cousin, Martin Guiton
This paper presents a joint statistical model that has been fitted to data of wind and wave conditions for an offshore location off South Brittany. The data are from a numerical model and contain hourly values for several wind and wave variables over a period of 32 years. The joint distribution presented in this paper considers the variables wind direction, mean wind speed, significant wave height, wave direction and peak period. A conditional model for turbulence given wind speed is introduced to yield an additional variable for the joint model. The joint model is constructed as a product of marginal and conditional models for the various variables. Additionally, the fitted models will be used to construct environmental contours for some of the variables. For significant wave height, various models are used to obtain different extreme value estimates, illustrating the uncertainties involved in extrapolating statistical models beyond the support of the data, and a discussion on the use of non-parametric copulas for the joint distribution is presented. Moreover, bootstrap has been performed to estimate the uncertainty in estimated model parameters from sampling variability. The effect of changing which variable to model as the marginal in a conditional model is illustrated by switching from wind speed to significant wave height. Such joint distribution models are important inputs for design of offshore structures, and in particular for offshore wind turbines, and the influence of the joint model in design is illustrated by a simple case study.
{"title":"A JOINT PROBABILITY DISTRIBUTION FOR MULTIVARIATE WIND-WAVE CONDITIONS AND DISCUSSIONS ON UNCERTAINTIES","authors":"Erik Vanem, E. Fekhari, Nikolay K. Dimitrov, Mark Kelly, Alexis Cousin, Martin Guiton","doi":"10.1115/1.4064498","DOIUrl":"https://doi.org/10.1115/1.4064498","url":null,"abstract":"\u0000 This paper presents a joint statistical model that has been fitted to data of wind and wave conditions for an offshore location off South Brittany. The data are from a numerical model and contain hourly values for several wind and wave variables over a period of 32 years. The joint distribution presented in this paper considers the variables wind direction, mean wind speed, significant wave height, wave direction and peak period. A conditional model for turbulence given wind speed is introduced to yield an additional variable for the joint model. The joint model is constructed as a product of marginal and conditional models for the various variables. Additionally, the fitted models will be used to construct environmental contours for some of the variables. For significant wave height, various models are used to obtain different extreme value estimates, illustrating the uncertainties involved in extrapolating statistical models beyond the support of the data, and a discussion on the use of non-parametric copulas for the joint distribution is presented. Moreover, bootstrap has been performed to estimate the uncertainty in estimated model parameters from sampling variability. The effect of changing which variable to model as the marginal in a conditional model is illustrated by switching from wind speed to significant wave height. Such joint distribution models are important inputs for design of offshore structures, and in particular for offshore wind turbines, and the influence of the joint model in design is illustrated by a simple case study.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139619763","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}
Ship hull vibration is a significant contributor to fatigue crack growth and the major sources of vibrations are found to be the main engine vibration excitation, the wave-induced springing and whipping loads, and the action of the propeller. In the midship region, wave-induced loads and the main engine are the major contributors, whereas propeller excitation dominates in the aft region of the ship hull. No general method exists to solve all kinds of vibration problems and they need to be evaluated through a cost-by-case approach. The complex and uncertain aspects of hull vibration and fatigue crack growth motivate the need for a reliability-based scheme for assessing the resulting fatigue crack propagation. In the present paper, a probabilistic formulation for the failure probability of the occurrence of crack propagation of a secondary hull component is outlined. A generic cargo hold model is analyzed with engine excitation and wave-induced loading as vibration sources, and a stochastic model for vibration response is outlined. The limit state is formulated as the possible occurrence of fatigue crack growth. The secondary hull component considered is a pipe stack support, which is a supporting component that attaches the cargo pipes to the wall inside a cargo tank. Different initial crack sizes are implemented to evaluate the adequacy of the applied stochastic model for vibration response and the accuracy of the estimated failure probability is assessed.
{"title":"Reliability Analysis of Crack Growth Occurrence for a Secondary Hull Component due to Vibration Excitation","authors":"Siri Kolle Kleivane, B. Leira, Sverre Steen","doi":"10.1115/1.4064499","DOIUrl":"https://doi.org/10.1115/1.4064499","url":null,"abstract":"\u0000 Ship hull vibration is a significant contributor to fatigue crack growth and the major sources of vibrations are found to be the main engine vibration excitation, the wave-induced springing and whipping loads, and the action of the propeller. In the midship region, wave-induced loads and the main engine are the major contributors, whereas propeller excitation dominates in the aft region of the ship hull. No general method exists to solve all kinds of vibration problems and they need to be evaluated through a cost-by-case approach. The complex and uncertain aspects of hull vibration and fatigue crack growth motivate the need for a reliability-based scheme for assessing the resulting fatigue crack propagation. In the present paper, a probabilistic formulation for the failure probability of the occurrence of crack propagation of a secondary hull component is outlined. A generic cargo hold model is analyzed with engine excitation and wave-induced loading as vibration sources, and a stochastic model for vibration response is outlined. The limit state is formulated as the possible occurrence of fatigue crack growth. The secondary hull component considered is a pipe stack support, which is a supporting component that attaches the cargo pipes to the wall inside a cargo tank. Different initial crack sizes are implemented to evaluate the adequacy of the applied stochastic model for vibration response and the accuracy of the estimated failure probability is assessed.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139527947","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 marginal ice zone (MIZ) is the area between sea ice and open water, the structure of which is mainly determined by wave and ice interactions. Thus mastering the characteristics of MIZ is of great significance to the Arctic routes opening and the natural resources development. In this paper, the hydroelastic response of ice floes in waves is studied, a three-dimensional numerical wave tank is established based on the computational fluid dynamics (CFD) technology. The finite volume method (FVM) and finite element method (FEM) are respectively utilized for discrete fluid domain and ice domain. A mapping interface at the junction of the fluid and ice floes domains is created to perform data mapping by the shape function interpolation method and the least square method. This work presents a series of numerical simulations to study the fluid-solid interaction (FSI) of waves and ice floes. Under the given incident wave parameters, the vertical bending deformation of ice floes with different shapes under the excitation of waves, the effect of ice floes' deformation on the wave field are studied, and the effect of wave overwash on the transmitted wave field is emphasized. Results show that the shape of the ice floes significantly affects its elastic deformation and scattered wave field, and the wave overwash phenomenon attenuates the scattering wave.
{"title":"Research on the hydroelastic response of ice floes and wave scattering field","authors":"Xi Zhang, Tingqiu Li, Zuyuan Liu","doi":"10.1115/1.4064497","DOIUrl":"https://doi.org/10.1115/1.4064497","url":null,"abstract":"\u0000 The marginal ice zone (MIZ) is the area between sea ice and open water, the structure of which is mainly determined by wave and ice interactions. Thus mastering the characteristics of MIZ is of great significance to the Arctic routes opening and the natural resources development. In this paper, the hydroelastic response of ice floes in waves is studied, a three-dimensional numerical wave tank is established based on the computational fluid dynamics (CFD) technology. The finite volume method (FVM) and finite element method (FEM) are respectively utilized for discrete fluid domain and ice domain. A mapping interface at the junction of the fluid and ice floes domains is created to perform data mapping by the shape function interpolation method and the least square method. This work presents a series of numerical simulations to study the fluid-solid interaction (FSI) of waves and ice floes. Under the given incident wave parameters, the vertical bending deformation of ice floes with different shapes under the excitation of waves, the effect of ice floes' deformation on the wave field are studied, and the effect of wave overwash on the transmitted wave field is emphasized. Results show that the shape of the ice floes significantly affects its elastic deformation and scattered wave field, and the wave overwash phenomenon attenuates the scattering wave.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139528366","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}
When estimating significant wave height and wave power, it is regularly assumed 4 for the spectral estimate factor. It means considering a narrowband wave spectrum. That approach is accurate enough when the spectral broadness parameter is near zero. Since the Peru Basin is an open ocean: swells and local wind waves can overlap; therefore, its wave spectrum should be considered broadband. This work aims to demonstrate that the wave spectrum in Peru Basin has waves in a broad band of frequencies and also discuss how this characteristic affects estimating the significant wave height and wave power. The methodology comprises numerical methods, inferential statistics and spectral analysis applied to ocean data. The paper's conclusions declare the Peru Basin wave spectrum as broadband. The estimated significant wave height for broadband wave spectrum is 7% lower than if the wave spectrum was considered narrowband. We propose 3.7 as the spectral estimate factor for calculating the significant wave height in the Peru Basin instead of the commonly used 4. The significant wave height error when assuming a narrowband wave spectrum slightly affects the spectral parametric wave power calculation, causing a maximum overestimation of 5%. Nevertheless, accurately estimating significant wave height is critical for diverse marine technologies.
{"title":"Effect of Broadness of Wave Spectrum on Significant Wave Height and Wave Power for Open Ocean Conditions of the Peru Basin","authors":"Dennys De La Torre, Jaime Luyo, Arturo Ortega","doi":"10.1115/1.4064501","DOIUrl":"https://doi.org/10.1115/1.4064501","url":null,"abstract":"\u0000 When estimating significant wave height and wave power, it is regularly assumed 4 for the spectral estimate factor. It means considering a narrowband wave spectrum. That approach is accurate enough when the spectral broadness parameter is near zero. Since the Peru Basin is an open ocean: swells and local wind waves can overlap; therefore, its wave spectrum should be considered broadband. This work aims to demonstrate that the wave spectrum in Peru Basin has waves in a broad band of frequencies and also discuss how this characteristic affects estimating the significant wave height and wave power. The methodology comprises numerical methods, inferential statistics and spectral analysis applied to ocean data. The paper's conclusions declare the Peru Basin wave spectrum as broadband. The estimated significant wave height for broadband wave spectrum is 7% lower than if the wave spectrum was considered narrowband. We propose 3.7 as the spectral estimate factor for calculating the significant wave height in the Peru Basin instead of the commonly used 4. The significant wave height error when assuming a narrowband wave spectrum slightly affects the spectral parametric wave power calculation, causing a maximum overestimation of 5%. Nevertheless, accurately estimating significant wave height is critical for diverse marine technologies.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139618179","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}
F. Cenci, Aline Leal de Lima Gontarski, Maria Eduarda Felippe Chame, Cláudia Martins Peri Machado dos Santos, Rodolfo T. Gonçalves, A. Fujarra
This work presents experimental results on Vortex-induced Vibration (VIV) of a horizontal cylinder with 2.69m in length, 21mm in diameter, and a mass ratio equal to 3.9. The experiments were carried out in a towing tank, where the flexible cylinder was towed under constant current profiles. Twenty reduced velocities were tested in a range of 1.75 < Vr < 15.79, corresponding to Reynolds numbers from 1,000 to 10,000. The displacements were measured directly through a submerged optical system that simultaneously acquired the in-line and cross-flow movement of 18 reflective targets along the length. The extensive monitored section of the model enabled the application of a modal decomposition technique, which is a methodology that is still relatively unexplored through direct measurements. A comprehensive analysis was applied and the VIV responses related to amplitudes, frequencies, phase angles, and trajectories are shown and discussed in depth. The overall dynamics exhibits a multimodal response behavior, and the modal decomposition procedure has conclusively confirmed that the total amplitude comprises several modes vibrating at the dominant mode frequency. Root mean square values of response amplitude were up to 0.77D and 0.23D in the cross-flow and in-line directions, respectively. The cross-flow synchronization had a significant impact on the in-line excitation modes, and the trajectories showed coherence between motions.
{"title":"Direct Measurements of Vortex-Induced Vibrations on a Horizontal Flexible Cylinder in Water","authors":"F. Cenci, Aline Leal de Lima Gontarski, Maria Eduarda Felippe Chame, Cláudia Martins Peri Machado dos Santos, Rodolfo T. Gonçalves, A. Fujarra","doi":"10.1115/1.4064474","DOIUrl":"https://doi.org/10.1115/1.4064474","url":null,"abstract":"\u0000 This work presents experimental results on Vortex-induced Vibration (VIV) of a horizontal cylinder with 2.69m in length, 21mm in diameter, and a mass ratio equal to 3.9. The experiments were carried out in a towing tank, where the flexible cylinder was towed under constant current profiles. Twenty reduced velocities were tested in a range of 1.75 < Vr < 15.79, corresponding to Reynolds numbers from 1,000 to 10,000. The displacements were measured directly through a submerged optical system that simultaneously acquired the in-line and cross-flow movement of 18 reflective targets along the length. The extensive monitored section of the model enabled the application of a modal decomposition technique, which is a methodology that is still relatively unexplored through direct measurements. A comprehensive analysis was applied and the VIV responses related to amplitudes, frequencies, phase angles, and trajectories are shown and discussed in depth. The overall dynamics exhibits a multimodal response behavior, and the modal decomposition procedure has conclusively confirmed that the total amplitude comprises several modes vibrating at the dominant mode frequency. Root mean square values of response amplitude were up to 0.77D and 0.23D in the cross-flow and in-line directions, respectively. The cross-flow synchronization had a significant impact on the in-line excitation modes, and the trajectories showed coherence between motions.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139532556","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 interaction between surface gravity waves and surface-piercing vertical multi-plate breakwaters in finite water depth is investigated under the assumption of potential flow theory. The time-domain desingularized boundary integral equation method (DBIEM) is adopted to solve the boundary value problem. A decomposition method based on the superposition principle is used to obtain reflected waves. The effect of the vertical plates as a floating breakwater by making full use of Bragg resonance is analyzed. Initially, the waveforms calculated without breakwaters are compared with second-order Stokes regular wave to obtain the appropriate desingularization distance. Then, the interaction of surface gravity waves with the breakwaters with the single plate, double and triple plates are analyzed. The transmission and reflection coefficients of the breakwater with the single plate are verified with the analytical solutions of previous literature. The transmission and reflection coefficients of the breakwaters with double and triple plates are verified with experimental results. Finally, the transmission and reflection coefficients of surface-piercing vertical multi-plate breakwaters with different plate numbers and drafts are also calculated. The occurring condition of Bragg resonance and its values affected by the plate number and the draft are analyzed. The present results are reference values for the optimal design of vertical plates as a floating breakwater for offshore and coastal engineering applications by fully using Bragg resonance.
{"title":"BRAGG RESONANCE OF SURFACE GRAVITY WAVES BY SURFACE-PIERCING VERTICAL MULTI-PLATE BREAKWATERS","authors":"Changzhe Chen, Jing-Ping Wu, Jun Pan, Zaojian Zou","doi":"10.1115/1.4064390","DOIUrl":"https://doi.org/10.1115/1.4064390","url":null,"abstract":"\u0000 The interaction between surface gravity waves and surface-piercing vertical multi-plate breakwaters in finite water depth is investigated under the assumption of potential flow theory. The time-domain desingularized boundary integral equation method (DBIEM) is adopted to solve the boundary value problem. A decomposition method based on the superposition principle is used to obtain reflected waves. The effect of the vertical plates as a floating breakwater by making full use of Bragg resonance is analyzed. Initially, the waveforms calculated without breakwaters are compared with second-order Stokes regular wave to obtain the appropriate desingularization distance. Then, the interaction of surface gravity waves with the breakwaters with the single plate, double and triple plates are analyzed. The transmission and reflection coefficients of the breakwater with the single plate are verified with the analytical solutions of previous literature. The transmission and reflection coefficients of the breakwaters with double and triple plates are verified with experimental results. Finally, the transmission and reflection coefficients of surface-piercing vertical multi-plate breakwaters with different plate numbers and drafts are also calculated. The occurring condition of Bragg resonance and its values affected by the plate number and the draft are analyzed. The present results are reference values for the optimal design of vertical plates as a floating breakwater for offshore and coastal engineering applications by fully using Bragg resonance.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139452231","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}
In the process of coastal bridge construction, cofferdams become necessary facilities to ensure the construction environment dry and safe. However, during the construction period of coastal bridges, extreme surges and waves caused by typhoons can impose huge hydrodynamic loads at the cofferdam and a potential threat to the safety and integrity of cofferdam. Therefore, it becomes valuable to assess the hydrodynamic loads of bridge cofferdam under extreme waves. Meanwhile, in the harsh marine environment, waves tend to propagate in multiple directions. However, previous studies mainly focused on the hydrodynamic characteristics of cofferdam by waves that propagate in one direction. Few studies were carried out on the hydrodynamic characteristics of cofferdam under the action of extreme waves in multiple directions. To fill in the gaps in previous research, this study numerically studied the complex wave hydrodynamics of cofferdam under multidirectional extreme waves. Effects of several major factors, i.e., significant wave height, peak wave period, water depth, spreading angle, incident wave angle and submergence depth were systematically analyzed. It is desired that present research could enhance our understandings on the complex wave hydrodynamics of bridge cofferdam under multidirectional focused waves.
{"title":"Hydrodynamic characteristics of bridge cofferdam under multidirectional focused waves","authors":"X. Wang, K. Qu","doi":"10.1115/1.4064391","DOIUrl":"https://doi.org/10.1115/1.4064391","url":null,"abstract":"\u0000 In the process of coastal bridge construction, cofferdams become necessary facilities to ensure the construction environment dry and safe. However, during the construction period of coastal bridges, extreme surges and waves caused by typhoons can impose huge hydrodynamic loads at the cofferdam and a potential threat to the safety and integrity of cofferdam. Therefore, it becomes valuable to assess the hydrodynamic loads of bridge cofferdam under extreme waves. Meanwhile, in the harsh marine environment, waves tend to propagate in multiple directions. However, previous studies mainly focused on the hydrodynamic characteristics of cofferdam by waves that propagate in one direction. Few studies were carried out on the hydrodynamic characteristics of cofferdam under the action of extreme waves in multiple directions. To fill in the gaps in previous research, this study numerically studied the complex wave hydrodynamics of cofferdam under multidirectional extreme waves. Effects of several major factors, i.e., significant wave height, peak wave period, water depth, spreading angle, incident wave angle and submergence depth were systematically analyzed. It is desired that present research could enhance our understandings on the complex wave hydrodynamics of bridge cofferdam under multidirectional focused waves.","PeriodicalId":509714,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139390161","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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