A numerical framework for modelling the dynamics of open ocean aquaculture structures in viscous fluids

Martín, Tobías; Tsarau, Andrei; Bihs, Hans

doi:10.1016/j.apor.2020.102410

Cited by 53 publications

(41 citation statements)

References 42 publications

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“…in which Q is the axial uniform tensile force in the net, m s is the uniform mass of the net per unit length, and ρ is the water density. In [28], a comparison between the analytical model based on Equation (10) and the FEM simulation for the cylindrical net cage illustrates acceptable errors.…”

Section: Methods Of Solutionsmentioning

confidence: 98%

“…By substituting Equation (16a,b) into Equation (10) and noting the orthogonality of cos(mθ), m = 0, 1, 2 . .…”

Section: Methods Of Solutionsmentioning

confidence: 99%

“…However, these models neglect the interferences of the structure and its motions on the flow field. For this reason, some researchers, e.g., Bi et al [9] and Martin et al [10], introduced computational fluid dynamics (CFD) techniques to achieve a fluid-structure interaction (FSI), but this requires tremendous computational time. In [10], it is reported that the simulation of a semisubmersible cage in irregular waves by FSI takes around 185 h for 300 s of simulation time on 64 cores (Intel Sandy Bridge) with 2.6 Ghz and 2 GB memory per core.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Methods Of Solutionsmentioning

confidence: 98%

“…By substituting Equation (16a,b) into Equation (10) and noting the orthogonality of cos(mθ), m = 0, 1, 2 . .…”

Section: Methods Of Solutionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…The free surface is modelled using the level set method of Osher and Sethian [39] and Sussman et al [40]. The dynamics of rigid floating structures are coupled to the fluid solver using a continuous direct forcing method [41] and the incremental pressure-correction algorithm of Timmermans et al [42]. The third-order accurate TVD Runge-Kutta scheme of Shu and Osher [32] is applied to propagate the momentum and free surface in time, and the fifth-order accurate WENO schemes by Jiang and Peng [43] and Jiang and Shu [44] are used for convection terms.…”

Section: Coupling To the Fluid Solvermentioning

confidence: 99%

A Numerical Solution for Modelling Mooring Dynamics, Including Bending and Shearing Effects, Using a Geometrically Exact Beam Model

Martín

Bihs

2021

JMSE

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During the operation of moored, floating devices in the renewable energy sector, the tight coupling between the mooring system and floater motion results in snap load conditions. Before snap events occur, the mooring line is typically slack. Here, the mechanism of energy propagation changes from axial to bending dominant, and the correct modelling of the rotational deformation of the lines becomes important. In this paper, a new numerical solution for modelling the mooring dynamics that includes bending and shearing effects is proposed for this purpose. The approach is based on a geometrically exact beam model and quaternion representations for the rotational deformations. Further, the model is coupled to a two-phase numerical wave tank to simulate the motion of a moored, floating offshore wind platform in waves. A good agreement between the proposed numerical model and reference solutions was found. The influence of the bending stiffness on the motion of the structure was studied subsequently. We found that increased stiffness increased the amplitudes of the heave and surge motion, whereas the motion frequencies were less altered.

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“…In two-dimensional Cartesian coordinates, under steady currents and floater oscillations, the hydroelastic response of full-scale floater-and-net systems was investigated in [20]. Recently, a numerical framework for modelling open sea aquacultures in waves and currents based on CFD was developed to study the structural dynamics of the net [21]. Solidity was defined as the ratio of the projected area to the circumscribed area of the net, which is an essential parameter and determines the projected area.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analysis of the Effect of Currents on the Dynamics of a Moored Flexible Cylindrical Net Cage

Liu

Mohapatra

Soares

2021

JMSE

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A numerical model associated with wave–current interactions with a moored flexible cylindrical cage was developed based on the finite element method. An analytical model was formulated under the linearised wave theory and small structural response, and a semi-analytical solution was obtained using the Fourier Bessel series solution and least squares approximation method, along with a matching technique. The numerical results from the finite element analysis of the horizontal displacements for different design parameters under a uniform current were compared with the analytical model solutions. It was seen that they had a good level of agreement with their results. The effects of different current speeds and time on the cage shapes were analysed from the finite element results. Further, the mooring forces on the flexible cage for different values of the cage height and cage radius were also presented. The comparison of the results indicated that the numerical model results could be used with confidence in the design of a flexible cylindrical net cage for applications to offshore aquacultures.

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A numerical framework for modelling the dynamics of open ocean aquaculture structures in viscous fluids

Cited by 53 publications

References 42 publications

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

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

A Numerical Solution for Modelling Mooring Dynamics, Including Bending and Shearing Effects, Using a Geometrically Exact Beam Model

Finite Element Analysis of the Effect of Currents on the Dynamics of a Moored Flexible Cylindrical Net Cage

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