Examination of net volume reduction of gravity-type open-net fish cages under sea currents

Chen, Da; Wang, C.M.; Zhang, Hong

doi:10.1016/j.aquaeng.2020.102128

Cited by 20 publications

(11 citation statements)

References 38 publications

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“…Data given from the State of World Fisheries and Aquaculture (Food and Agriculture Organization, 2018) show that from 1950 to 2016, the output of aquatic products increased to 170 tons per year with an 850% growth rate, of which marine aquatic products accounted for approximately 69%. In Australia, the aquaculture industry has been in a fast-growing phase and provides high-quality, safe, and sustainable seafood, with output values reaching 3.3 billion Australian dollars in 2020 (Chen et al, 2021). These developments in marine aquaculture have provided a strong motivation in carrying out research and development of larger fish cage systems.…”

Section: Introductionmentioning

confidence: 99%

Analytical solutions of hydroelastic interactions between waves and submerged open-net fish cage modeled as a porous cylindrical thin shell

Zhang

Jeng

et al. 2022

Physics of Fluids

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In this paper, a new semi-analytical solution is proposed to describe the interactions between ocean waves and a flexible cylindrical net cage that is submerged at different depths below the mean water level. The flexible net is treated as a thin perforated shell, and its deformation is governed by the membrane vibration equation of cylindrical shells. The small-amplitude wave theory is adopted to simulate the wavefield, while the flow passing through the cage is described by the porous medium theory. The numerical results exhibit significant wave responses of the net cage, including the distribution properties of wave surfaces, dynamic pressure drops on the net interface, and net structure displacements. Furthermore, the influences of several important design parameters on the hydrodynamic action imposed on the net cage are revealed by parametric studies. The present studies conclude that the significant wave impact is mainly concentrated on the free water surface, and increasing the porosity and flexibility of the net can alleviate wave scattering and the hydrodynamic actions. In addition, at specific wave frequencies, the horizontal wave force acting on the cage will vanish. These findings should be useful to engineers who are designing offshore fish cage systems.

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Section: Introductionmentioning

confidence: 99%

Analytical solutions of hydroelastic interactions between waves and submerged open-net fish cage modeled as a porous cylindrical thin shell

Zhang

Jeng

et al. 2022

Physics of Fluids

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“…Moored floating structures can be simplified into a multi-point architecture, as shown in Figure 1. Each mooring line is equally discrete to N nodes, which are connected with massless springs [18]. The response of a floating structure is represented by that of a node at center of mass (COM).…”

Section: Moored Floating Structure Architecturementioning

confidence: 99%

The Quasi-Static Response of Moored Floating Structures Based on Minimization of Mechanical Energy

Chen

Choung

2021

JMSE

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It is essential to design a reasonable mooring line length that ensures quasi-static responses of moored floating structures are within an acceptable level, and that reduces the cost of mooring lines in the overall project. Quasi-static responses include the equilibrium position and the line tension of a moored floating structure (also called the mean value in a dynamic response), etc. The quasi-static responses derived by the classic catenary equation cannot present mooring–seabed interaction and hydrodynamic effects on a mooring line. While a commercial program can predict reasonable quasi-static responses, costly modeling is required. This motivated us to propose a new method for predicting quasi-static responses that minimizes the mechanical energy of the whole system based on basic geometric parameters, and that is easy to implement. In this study, the mechanical energy of moored floating structures is assumed to be the sum of gravitational–buoyancy potential energy, kinetic energy induced by drag forces, and spring potential energy derived by line tension. We introduce fundamental theoretical background for the development of the proposed method. We investigate the effect of quasi-static actions on mooring response, comparing the proposed method’s results with those from the catenary equation and ABAQUS software. The study reveals the shortcomings of the catenary equation in offshore applications. We also compare quasi-static responses derived by the AQWA numerical package with the results calculated from the proposed method for an 8 MW WindFloat 2 type of platform. Good agreement was drawn between the proposed method and AQWA. The proposed method proves more timesaving than AQWA in terms of modeling of mooring lines and floaters, and more accurate than the catenary equation, and can be used effectively in the early design phase of dimension mooring lengths for moored floating structures.

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“…Average data from 2015 to 2017 indicates that fish products provide at least 20% of the animal protein intake of 3.3 billion people [1], and aquatic products accounted for about 46.4% of the food and agriculture production in 2017 [2]. In addition, the aquaculture industry of Australia is in a stage of rapid development and reached an annual output value of AUD 3.3 billion in 2020 [3]. In order to guarantee a stable output, the fishing cage system requires excellent reliability under environmental loads, such as waves and currents.…”

Section: Introductionmentioning

confidence: 99%

A Semi-Analytical Model for Studying Hydroelastic Behaviour of a Cylindrical Net Cage under Wave Action

Zhang

Jeng

et al. 2021

JMSE

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In the present study, a semi-analytical model based on the small-amplitude wave theory is developed to describe the wave fields around a single gravity-type cylindrical open fish net cage. The cage may be submerged to different depths below the free-water surface. The fish cage net is modelled as a flexible porous membrane, and the deflection of the net chamber is expressed by the transverse vibration equation of strings. The velocity potential is expanded in the form of the Fourier–Bessel series and the unknown coefficients in these series are determined from matching the boundary conditions and the least squares method. The number of terms for the series solution to be used is determined from convergence studies. The model results exhibit significant hydroelastic characteristics of the net cages, including the distribution properties of wave surface, pressure drop at the net interface, structural deflection, and wave loading along the cage height. In addition, the relationships between wave forces on the net cage with hydrodynamic and structural parameters are also revealed. The findings presented herein should be useful to engineers who are designing fish cage systems.

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Examination of net volume reduction of gravity-type open-net fish cages under sea currents

Cited by 20 publications

References 38 publications

Analytical solutions of hydroelastic interactions between waves and submerged open-net fish cage modeled as a porous cylindrical thin shell

Analytical solutions of hydroelastic interactions between waves and submerged open-net fish cage modeled as a porous cylindrical thin shell

The Quasi-Static Response of Moored Floating Structures Based on Minimization of Mechanical Energy

A Semi-Analytical Model for Studying Hydroelastic Behaviour of a Cylindrical Net Cage under Wave Action

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