Experimental study on flow velocity and mooring loads for multiple net cages in steady current

Zhao, Yun; Bi, Chun Wei; Chen, Chang Ping; Li, Yu Cheng; Dong, Guohai

doi:10.1016/j.aquaeng.2015.05.005

Cited by 58 publications

(23 citation statements)

References 18 publications

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“…Fu et al [8] studied an extended three-dimensional hydro-elasticity theory to predict the dynamic response of 5 × 2 floating fish farm collars in waves. Zhao et al [9] performed a number of physical model experiments to study the main mooring line tensions and flow velocity magnitudes when the current flowed through multiple net cages. Zhou et al [10] presented hydrodynamic characteristics of knotless nylon netting normal to free stream and the effect of inclination angle on drag coefficient were discussed.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigations on Hydrodynamic Responses of a Semi-Submersible Offshore Fish Farm in Waves

Zhao

Guan

et al. 2019

JMSE

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A series of physical model experiments was performed to investigate the hydrodynamic responses of a semi-submersible offshore fish farm in waves. The structural configuration of the fish farm primarily refers to that of the world's first offshore fish farm, Ocean Farm 1, developed by SalMar in Norway. The mooring line tension and motion response of the fish farm were measured at three draughts. The study indicated that the tension on the windward mooring line is greater than that on the leeward mooring line. As the wave height increases, the mooring line tension and motion responses including the heave, surge, and pitch exhibit an upward trend. The windward mooring line tension decreased slightly with increasing draught. The existence of net resulted in approximately 42% reduction in mooring line tension and approximately 51% reduction in surge motion. However, the heave and pitch of the fish farm increased slightly with the existence of net. It was found that the wave parameters, draught, and net have noticeable effect on the hydrodynamic response. Thus, these factors are suggested to be considered in structural designs and optimization to guarantee the ability of the fish farm to resist destruction and ensure safety of workers during intense waves. weakness of development. The floaters and columns for a fish farm could be ideally used as a wave energy converter platform. The aquaculture platform of sufficient dimensions can support several wind turbines and realize self-power supply of the offshore fish farm. Overall, both the converter platform of wave energy and offshore wind turbine can be combined with this kind of new type of offshore aquaculture facility. Due to its superior performance, the offshore fish farm considered is accepted and widely used all over the world. Hence, fundamental research on the offshore fish farm is very critical, especially in the initial stage.

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Section: Introductionmentioning

confidence: 99%

Experimental Investigations on Hydrodynamic Responses of a Semi-Submersible Offshore Fish Farm in Waves

Zhao

Guan

et al. 2019

JMSE

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“…The hydrodynamic behaviors of multiple net cages in waves and current were investigated numerically by Xu et al (2012Xu et al ( , 2013b. Zhao et al (2015) also performed an experimental study on flow velocity and mooring loads for multiple net cages in steady current. The dynamic responses of a net cage in irregular waves were analyzed by Dong et al (2010) and Xu et al (2011).…”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental investigations on mooring loads of a marine fish farm in waves and current

Shen

Greco

Faltinsen

et al. 2018

Journal of Fluids and Structures

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A realistic aquaculture fish farm system in both regular and irregular waves is investigated by numerical simulations and model tests. The main purpose is to develop a reliable numerical tool and in this respect to investigate the survival conditions of the system. The structural and hydrodynamic modelings of the system are briefly introduced. Numerical sensitivity analysis is performed to investigate which physical parameters are dominant when modeling the system.The considered fish farm comprises a floating collar with two concentric tubes, a flexible net cage including a cylindrical part and a conical part with a center point weight at the bottom, and a sinker tube attached directly to the net. The system is moored with a complex mooring system with bridle lines, frame lines and anchor lines, supported by buoys.The mooring loads in the front two anchor lines and bridle lines are investigated in detail. Numerical results are first validated by the experimental data. Both numerical and experimental results show that one of the bridle lines experiences larger load than the rest of the mooring lines, which is surprising. Then a sensitivity analysis is carried out. The mooring loads are not sensitive to the majority of the parameters. The flow reduction factor in the rear part of the net is the most important parameter for the anchor loads. Modeling the floating collar as a rigid body has a small effect on the anchor loads but not for the bridle lines as it will alter the force distribution between bridles. The mooring loads are not sensitive to the wave load model for the floating collar in both regular and irregular seas and modeling the floating collar as elastic with zero frequency hydrodynamic coefficients is enough to give reliable results.Finally, the survival conditions of the fish farms with different set-ups is studied. Numerical results indicate that the dominant limitation to move the conventional fish farms to more exposed sea regions is the large volume reduction of the net cage. The existing mooring system can be applied in offshore regions as long as the bridle lines are properly designed. The maximum stress in the floating collar is moderate compared with the yield stress.

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“…The percentage reduction in current speed through the cage in the channel setup (Fig 4) was comparable in the Fluent (CFD) and SINMOD (ocean model) simulations, that were parametrized according to the field data in [24]. Other studies have reported different figures, e.g [29], but these are difficult to assess in the present context because they refer to either scale models or arrays of multiple cages. Previous simulation work has indicated that extensive aquaculture installations may reduce current speeds by more than 50% over large areas [9][10][11]30].…”

Section: Effects Of the Drag Parametrizationmentioning

confidence: 59%

Multiscale modelling of cage effects on the transport of effluents from open aquaculture systems

et al. 2020

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Most Atlantic salmon mariculture operations use open sea cages for the grow out phase. The ultimate fate and effects of the effluents and the possibilities of disease transfer between fish farms are major concerns for farmers, governance and the general public alike. Numerical model systems applied to studying and managing effluents and disease transfer in mariculture must realistically resolve the hydrodynamics in the vicinity of the fish farms. In the present study, the effects of the aquaculture structures on the current patterns were introduced in the ocean model system SINMOD. The drag parameters for the ocean model were determined by comparing the simulation results from the ANSYS Fluent ® software suite and SINMOD in an idealized channel setting with uniform currents. The model was run for a number of realistic scenarios in high horizontal resolution (*30 m) with sea cages influencing the flow field. Comparisons between extensive current measurements and the simulation results showed that the model system reproduced the current local current field well. By running simulation scenarios with and without the effects of the sea cages on the flow field, it was possible to assess the importance of such effects for numerical dispersal models and aquaculture environment interactions simulations and hence for assessment of environmental impacts.

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Experimental study on flow velocity and mooring loads for multiple net cages in steady current

Cited by 58 publications

References 18 publications

Experimental Investigations on Hydrodynamic Responses of a Semi-Submersible Offshore Fish Farm in Waves

Experimental Investigations on Hydrodynamic Responses of a Semi-Submersible Offshore Fish Farm in Waves

Numerical and experimental investigations on mooring loads of a marine fish farm in waves and current

Multiscale modelling of cage effects on the transport of effluents from open aquaculture systems

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