Frequency domain modelling of a coupled system of floating structure and mooring Lines: An application to a wave energy converter

Touzón, Imanol; Nava, Vincenzo; Gao, Zhen; Petuya, V.

doi:10.1016/j.oceaneng.2020.108498

Cited by 12 publications

(5 citation statements)

References 18 publications

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“…In addition, the porosity properties of the fishing net are unique compared to the typical offshore structures. The study of the hydrodynamic characteristics of the fishing net can be divided into two aspects: On the one hand, computational cost can be dramatically increased if the physical net meshes were directly modeled with the numerous small-scale rigid rods (Cornejo et al, 2014;Winthereig-Rasmussen et al, 2016;Yao et al, 2016;Touzon et al, 2021). On the other hand, the porous medium method to describe the small-scale rigid rod was adopted (Bi et al, 2014;Zhao et al, 2015); as a result, the real influences of the topology as well as the structural details of net meshes are overlooked.…”

Section: Component Of the Floating Reefmentioning

confidence: 99%

“…The primary methods are the static and dynamic analysis (Tu et al, 2020). The lumped mass point model is a common method to study the dynamic response of mooring systems (Zhu et al, 2016a;Pan et al, 2021;Palo et al, 2021;Feng et al, 2021a;Zhu et al, 2020;Touzon et al, 2021). The dynamic safety performance of the floating platform with iron chain was studied by Gobat and Grosenbaugh (2001); Agarwal and Jain (2003), and Umar and Datta (2003).…”

Section: Component Of the Floating Reefmentioning

confidence: 99%

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Review of Structure Types and New Development Prospects of Artificial Reefs in China

et al. 2022

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Artificial reefs are beneficial to restore fishery resources and increase fishery production. Meanwhile, they play a significant role in improving ocean ecology and accelerating the evolution of fishery industries. Since they are generally affected by currents, waves, and other hydrological factors, the flow field around artificial reefs and their stabilities have become a research hotspot in recent years. Research on artificial reefs is a systematic process consisting of four aspects: Firstly, the significance, the definition, the mechanism, and the present research progress were introduced for artificial reefs in detail. Secondly, the development trend of the sit-bottom artificial reef and that of the floating artificial reef were summarized, respectively. Thirdly, it was found that the combination of traditional artificial reefs and emerging ocean engineering has a great development potential in practical engineering. Finally, the existing problems related to the hydrodynamic characteristics of the artificial reefs in China were summarized, and the prospects of artificial reefs were proposed. The purpose of this study is to provide a scientific reference for the ecological and sustainable development of the large-scale construction of artificial reefs in the ocean.

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Section: Component Of the Floating Reefmentioning

confidence: 99%

Section: Component Of the Floating Reefmentioning

confidence: 99%

Review of Structure Types and New Development Prospects of Artificial Reefs in China

et al. 2022

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“…Main sources of non-linearity are the viscous forces on both the floater and mooring nodes, the geometric stiffness of catenary lines and the fairlead and anchor relations between the structure and mooring line ends. These effects are linearized in this approach in order to enable the FD solution of the whole coupled model, as specified in 23 , as well as the modal analysis, represented in Fig. 4.…”

Section: Dynamic Linearized Frequency Domainmentioning

confidence: 99%

“…The non-linear geometric stiffness contributes significantly to the system performance, especially in cases with significant mooring pretensions and in the LF range. Its influence on both the floater and mooring lines can be obtained through the secant stiffness force on the structure, as carried out in 23 accounting for two standard deviations of each degree of freedom of the floater about the mean position.…”

Section: Dynamic Linearized Frequency Domainmentioning

confidence: 99%

Numerical Approaches for Loads and Motions Assessment of Floating WECs Moored by Means of Catenary Mooring Systems

Touzón¹,

Petuya²,

Nava³

et al. 2021

Proceedings of I4SDG Workshop 2021

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Technologies for harvesting offshore renewable energy based on floating platforms, such as offshore wind, wave and tidal energies, are currently being developed with the purpose of achieving a competitive cost of energy. The economic impact of the mooring system is significant within the total cost of such deployments, and large efforts are being carried out to optimize designs. Analysis of mooring systems at early stages generally require a trade-off between quick analysis methods and accuracy to carry out multi-variate sensitivity analyses. Even though the most accurate approaches are based on the non-linear finite element method in the time domain, these can result in being very time consuming. The most widely used numerical approaches for mooring line load estimates are introduced and discussed in this paper. It is verified that accurate line tension estimates require lines drag and inertia forces to be accounted for. A mooring and floating structure coupled model based on the lumped mass finite element approach is also discussed, and it is confirmed that the differences found in the coupled numerical model are mainly produced by the uncertainty on hydrodynamic force estimates on the floating structure rather than by the lumped mass method. In order to enable quick line tension estimates, a linearization of the structure and mooring coupled model is discussed. It shows accurate results in operational conditions and enables modal analysis of the coupled system.

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“…The structure design, material selection and mooring methods of floating reefs are the focus of research all over the world [3][4][5]. The finite element method and lumped mass point method are mostly used to establish the numerical model of artificial floating reefs, and the purpose is to study the hydrodynamic characteristics of floating reefs [6][7][8]. Marine aquaculture cages were used to study the initial stage of floating reefs because there are many similarities between the structure of floating reefs and marine aquaculture cages.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Hydrodynamic Characteristics of Layered Floating Reefs under Tidal Currents and Waves

Pan,

Yang,

Xue

et al. 2023

Water

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Artificial floating reefs are an important supplement to bottom reefs in marine habitat construction, which provide a good environment for fish to survive, breed and habituate in the middle and upper layers of water. They can adapt to the silt bottom of the East China Sea. To make full use of the water space and improve the effective space of the floating reef, based on the field tidal current data, an upper- and lower-layered artificial floating reef has been designed in this study. The connection method of the upper and lower reefs has been described in detail and a hydrodynamic numerical model has been established. At the same time, the effects of floating reef structure ratio, wave height and wave steepness on its force and motion are discussed under the action of tidal current and wave current. The result shows that, at a specific flow rate, the change of the proportion of the layered floating reef structure had little effect on the roll of the upper and lower reefs. The maximum roll angle does not exceed 15°, and the tilt angle of the upper and lower reefs is consistent, which ensures the good flow resistance and stability of the floating reef. Under the specific length of the connecting cable and the main mooring, the hydrodynamic characteristics of the layered floating reef are better when the ratio of the sum height of the lower reef and the connecting cable to the height of the upper reef is not greater than one and the extreme proportion structure is not considered. The tension of the stratified floating reef is proportional to the wave height and wave steepness under the action of wave and current. The main mooring rope is the most stressed, and the rolling motion of the upper and lower reefs is consistent. Above all, results can provide a theoretical basis for the optimization design of the artificial floating reef structure.

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Frequency domain modelling of a coupled system of floating structure and mooring Lines: An application to a wave energy converter

Cited by 12 publications

References 18 publications

Review of Structure Types and New Development Prospects of Artificial Reefs in China

Review of Structure Types and New Development Prospects of Artificial Reefs in China

Numerical Approaches for Loads and Motions Assessment of Floating WECs Moored by Means of Catenary Mooring Systems

Numerical Simulation of Hydrodynamic Characteristics of Layered Floating Reefs under Tidal Currents and Waves

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