Dynamic properties of a flexible net sheet in waves and current—A numerical approach

Lader, Pål; Fredheim, Arne

doi:10.1016/j.aquaeng.2006.02.002

Cited by 79 publications

(36 citation statements)

References 2 publications

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“…21-23. Lader and Fredheim (2006) found that the mean position of a net exposed to waves and current is approximately equal to the static deformation of the net when exposed to current only condition. Similar to the results of the previous studies Fredheim 2006, Shen et al 2015), Fig.…”

Section: Floater Oscillations Combined With a Steady Currentmentioning

confidence: 99%

“…Although little difference in the reduced projected area is observed in the lower sections with oscillatory flows, differences can be observed in the upper sections. This can be explained by the fact that for an oscillating floater, larger hydrodynamic forces act on the upper parts of the net (Lader and Fredheim 2006), causing those parts to deform more severely. Moreover, similar to the variation in the drag coefficient, smaller oscillatory periods and larger amplitudes lead to smaller values of the exposed area reduction coefficient in the upper sections.…”

Section: Floater Oscillationsmentioning

confidence: 99%

“…Fish-farming structures exhibit hydroelastic behavior when subjected to waves and currents. Therefore, accurate predictions of the hydroelastic response of fish cages are of critical importance (Lader and Fredheim 2006).…”

Section: Introductionmentioning

confidence: 99%

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A Hybrid Empirical-Numerical Method for Hydroelastic Analysis of a Floater-and-Net System

et al. 2016

Journal of Ship Research

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Because of scale effects and inappropriate hydrodynamic models, the nonlinear hydroelastic response of net cages used for fish farming cannot be analyzed precisely with traditional model testing or combinations of FEMs (finite element methods) and load models. In this study, an innovative hybrid method is proposed to determine the hydroelastic response of full-scale floater-and-net systems more accurately. In this method, the net for the fish cage was vertically and peripherally divided into similar interconnected sections with different hydrodynamic parameters, which were assumed to be uniformly distributed over each section. A model of a typical section was subjected to various towing velocities, oscillation periods and amplitudes in a towing tank to simulate the potential motions of all sections in the net under various currents, waves and floater movements. By analyzing the measured hydrodynamic force from this test section, a hydrodynamic force database for a typical net section under various currents, waves and floater motions was built. Finally, based on an FEM, the modified Morison equation and the hydrodynamic force database, the hydroelastic behavior of the full-scale fish cage was calculated with an iterative scheme. It is demonstrated that this hybrid method is able to produce correct hydroelastic response for both steady and oscillatory flows. The hydroelastic response of a 2D example of a full-length net panel with steady currents and floater oscillations was studied in detail.

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Section: Floater Oscillations Combined With a Steady Currentmentioning

confidence: 99%

Section: Floater Oscillationsmentioning

confidence: 99%

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A Hybrid Empirical-Numerical Method for Hydroelastic Analysis of a Floater-and-Net System

et al. 2016

Journal of Ship Research

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“…Tsukrov et al 2003 proposed a numerical model to analyze the hydrodynamic response of net panels to environmental loading with the concept of consistent finite element. Lader and Fredheim 2006 investigated dynamic properties of a flexib le net sheet exposed to waves and current by numerical simu lation, in wh ich the net was modeled by dividing it into super elements. Kristiansen and Faltinsen 2012 proposed a screen type of force model for the v iscous hydrodynamic load on nets, in which the net is divided into a number of flat net panels, or screens.…”

Section: Introductionmentioning

confidence: 99%

Untitled

Xu¹,

Hou²,

Dong³

et al. 2017

Turk. J. Fish. Aquat. Sci.

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Float collar is an important component for the fish cage systems which are applied by the aquaculture industry. The integrity and reliability of the float collar are detrimental in order to avoid the critical failure which may lead to major loss and severe consequences. A finite element model for the structural analysis of the float collar for the metal fish cage in waves is developed and validated by comparing with the experimental data. The numerical simulation is performed to conduct the parametrical study of float collar and to analyze the deformation and the stress of a met al fish cage in waves. The results indicate that the numerical model can accurately predict the deformation of float collar and the tension force on mooring line. When the central angle of the arc between two neighboring clamps is larger than 15°, the influence of the amount of clamps on the deformation of float collar is decreased significantly. For the metal fish cage structure, the upper part of the nets for the metal fish cage experiences the largest deformation, and thus the diameter of the net twine at the upper part of the metal fish cage should be increased to avoid the structural failure.

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“…, Fredriksson et al (2003Fredriksson et al ( , 2007 , Lader and Fredheim (2006) 3 . , Huang et al (2006) , Thomassen (2008) , Lee et al (2008) , Kim (2009) .…”

mentioning

confidence: 99%

Dynamic behavior of a submersible fish cage rigged with a circular floating and a sinking collar

Lee¹,

Lee²,

Choe³

et al. 2010

Journal of the Korean society of Fisheries Technology

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In this research, the submersible fish cage was designed to avoid structural and biological damage during harsh sea conditions. The submersible cage system consists of netting, mooring ropes, a floating collar, floats, sinkers and anchors. Whole elements of the cage were modeled on the mass-spring model. The computer simulations were carried out to investigate the dynamic behavior of the cage and to calculate mooring line tension subjected to tidal currents and waves. As expected, the tension values in the mooring line of the submerged position are 36% less compared to that of the surface cage under the same loading conditions. As the wave was used in combination with the current velocity of 1m/s, the average tensile load for the submerged cage showed 85% of the value for the floating cage. The simulation results provide an improved understanding of the behaviors of the structure and valuable information on the optimized design of the cage system exposed to open ocean environmental factors.

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Dynamic properties of a flexible net sheet in waves and current—A numerical approach

Cited by 79 publications

References 2 publications

A Hybrid Empirical-Numerical Method for Hydroelastic Analysis of a Floater-and-Net System

A Hybrid Empirical-Numerical Method for Hydroelastic Analysis of a Floater-and-Net System

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Dynamic behavior of a submersible fish cage rigged with a circular floating and a sinking collar

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