Design evaluation of a fish cage mooring system with different bridle line connections using model experiments and simulations

Park, Subong; Lee, Jihoon; Lee, Chun‐Woo

doi:10.1016/j.aquaeng.2021.102177

Cited by 14 publications

(6 citation statements)

References 14 publications

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“…The research of mooring systems on floating collar net cage usually correlates with strength analysis of mooring lines, collar offset, and fish net volume reduction. Previous research has studied the strength of mooring lines and fish net volume reduction based on spread mooring configuration [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Comparative study of spread and vertical mooring configuration in floating collar net cage under irregular waves and current

Murdjito,

Athallah,

Prasetywan

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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Offshore aquaculture is one of the national strategic programs of the Ministry of Fishery and Ocean Affairs of Indonesia to increase national fish cultivation capacity. One solution is using a simple flexible floating collar net which is suitable for small to medium cage volume. In designing such floating net, its mooring line configuration is vital to maintain fixed position of structural part of the cage volume. The purpose of this study is to compare design aspect of two types of mooring systems, i.e., spread and vertical configuration, by investigating selected parameters: mooring line tension, collar offset, and volume reduction. The mooring configuration and floating collar net cage are analysed through a numerical model based on Morison-force equations, under environmental condition adopted from Kangean field East Java. Load cases from collinearly in-line and between-line directions under extreme waves and current condition are checked against relevant safety factor. The dynamics analysis using the time domain simulation is based on 900 seconds cut-off according to its maximum wave elevation profile to generate the hydrodynamics forces to the mooring systems.

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Section: Introductionmentioning

confidence: 99%

“…Researchers have found that a proper mooring line configuration will affect the fish net volume, as it contributes to small or large fish net volume reduction [5][6][7]. When the fish net volume reduction is large, the economical of a floating collar net cage will reduce significantly which lead to inefficient of the system.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of spread and vertical mooring configuration in floating collar net cage under irregular waves and current

Murdjito,

Athallah,

Prasetywan

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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“…According to (Xu and Qin, 2020), physical model tests and field measurements have been conducted to understand hydrodynamic behaviors of net panels and aquaculture systems in steady flow (Bi et al, 2013;DeCew et al, 2013;Klebert and Su, 2020;Tang et al, 2021), oscillating flow (Liu et al, 2012) and waves (Fredriksson et al, 2003;Fredriksson et al, 2004;Lader et al, 2007;Zhao et al, 2008;Park et al, 2021). Many experimental tests examined the biofouling effects on net panels (Swift et al, 2006;Bi et al, 2018;Bi et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Numerical studies on wake and turbulence characteristics of aquaculture nets

Qin

2022

Front. Mar. Sci.

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This paper aims to understand the drag coefficient discrepancy between the equivalent-twine and twisted-twine nets based on their wake and turbulence characteristics. To that end, we conduct unsteady Reynolds-averaged Navier-Stokes (URANS) and the second-moment (Reynolds stress, RSM) simulations at a Reynolds number, Re=4.5×103, based on the effective diameter of the net twine, which corresponds to the subcritical flow regime. Then, the vortex structures and the turbulence statistics are assessed at AOA=90°. The results highlight that the wake interactions for the twisted-twine net are relatively strong compared to the equivalent-twine net, due to the disturbance of the helixes on the twisted twines. In comparison to the classical Karman vortex, the overall vortex shedding of these two nets is well organized. Symmetric vortices form behind the equivalent-twine net, while single vortices form behind the twisted-twine net. Moreover, the Reynolds normal and shear stresses show symmetric and anti-symmetric profiles. The addition of helixes to smooth circular cylinders changes the flow development, leading to a decrease of turbulence kinetic energy. With this understanding, engineers need to be carefully select the net type for preliminary design of marine aquaculture cages to avoid over- or underestimation of the drag forces.

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“…With the contributions of considerable researchers working at SINTEF Ocean (Endresen et al, 2013(Endresen et al, , 2014Reite et al, 2014;Skjong et al, 2021;Su et al, 2021Su et al, , 2019Endresen and Klebert, 2020), the computer program FhSim was successfully developed with considerable verifications and applied to various applications, such as fish cages in rough seas, trawl net system and aquaculture operation. Lee (2002) and Cha and Lee (2002) developed a numerical tool for fishing gears and later applied it to fish cage analysis (Lee et al, 2008;Lee et al, 2015;Park et al, 2021). This numerical tool turned into commercial software, SimuTrawl, SimuPurse and SimuLine, under the company MPSL.…”

Section: Introductionmentioning

confidence: 99%

“…1.2 State of the art in aquaculture structural designs Endresen et al, 2013;Endresen et al, 2014;Skjong et al, 2021;Su et al, 2021Su et al, , 2019; Endresen and Klebert, 2020 DUT-FlexSim Morison Mass-spring Li et al 2006a, 2006bZhao et al 2007a, 2007c SimuTrawl\ SimuPurse\ SimuLine Screen Mass-spring Lee et al, 2005;Lee et al, 2008;Lee et al, 2015;Park et al, 2021 NaLA Morison Mass-spring Takagi et al, 2002;Tsukrov et al, 2003;Suzuki et al, 2003;Shimizu et al, 2007;Takagi et al, 2014 1 Introduction…”

Section: Introductionmentioning

confidence: 99%

Development of Advanced Numerical Tools for Dynamic Analysis of Aquaculture Structures

Cheng¹

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Numerical methods to accurately predict dynamic responses of marine aquaculture structures are essential in the engineering design process, because these structures can be subjected to large wave and current loads in the ocean environment, which causes complex structural motion and deformation. However, only a few numerical programs for the dynamic analysis of aquaculture structures can be accessed by the public without permission. In order to meet the high demand for a ready-for-use program, a numerical module for an open-source Finite Element Analysis (FEA) program, Code_Aster, is developed in this PhD study. This numerical module includes various wave models (e.g., Airy waves, Stokes 2nd order waves and irregular waves) and hydrodynamic force models (e.g., Morison model, Screen model and flow velocity reduction due to wake effects). Moreover, a coupling algorithm to handle the wake effects of thin, flexible and highly permeable structures with complex geometries is also implemented to solve the complex fluid-structure interaction (FSI) problem in marine aquaculture engineering. The accuracy of structural response prediction can be improved using the coupling algorithm with the open-source Computational Fluid Dynamics (CFD) solver, OpenFOAM, which can solve the complex flow field around the structures. Detailed verifications and validations are firstly conducted with considerations of different net solidities, inflow angles, incoming current velocities and net dimensions. Subsequently, the newly developed numerical module is applied to study dynamic responses of traditional fish cages, grid moored fish farms and a large semi-submersible aquaculture structure for practical engineering design and optimization purposes. The structural responses of traditional fish cages with different design parameters (including circumferences of floating collar, depths of net bag, submerged weights) are comprehensively analyzed under pure current conditions. Based on the parametric analysis with a large number of numerical simulations, regression functions for the most concerning aspects are provided for engineering usages in the design process. These regression functions can save considerable time for experiments and numerical simulations in the design of traditional fish cages. The structural responses of grid moored fish farms are analyzed with respect to combinations of mooring line breakages and current directions. Based on the numerical results, suggestions to improve the design of the mooring system are given. It is also recommended to monitor the positions of buoys during in-situ operations. When one of the mooring line breaks, the maximum tension increment in the mooring system can be estimated based on the displacement of the buoys. This estimation can help the farmer to decide whether the damaged mooring line should be repaired immediately. The global responses of a semi-submersible offshore aquaculture structure are investigated under irregular waves and current conditions which correspond to a return period of 50 years. The numerical model shows a reasonable agreement with published experimental results and demonstrates that the newly developed numerical module can be applied to the dynamic analysis of offshore aquaculture structures.

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Design evaluation of a fish cage mooring system with different bridle line connections using model experiments and simulations

Cited by 14 publications

References 14 publications

Comparative study of spread and vertical mooring configuration in floating collar net cage under irregular waves and current

Comparative study of spread and vertical mooring configuration in floating collar net cage under irregular waves and current

Numerical studies on wake and turbulence characteristics of aquaculture nets

Development of Advanced Numerical Tools for Dynamic Analysis of Aquaculture Structures

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