Current Loads on Net Panels With Rhombic Meshes

Enerhaug, Birger; Føre, Martin; Endresen, Per Christian; Madsen, Nina; Hansen, Kurt Schaldemose

doi:10.1115/omae2012-83394

Cited by 8 publications

(7 citation statements)

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“…A detailed explanation of the net model and mathematical basis is given in Endresen et al (2013Endresen et al ( , 2014 and Enerhaug et al (2012). In the following, a brief overview of the principles and mathematical methods used in the net model is presented.…”

Section: Theorymentioning

confidence: 99%

“…The normal drag coefficient is dependent on the mesh bar Reynolds number and set according to the polynomial presented in Kristiansen and Faltinsen (2012). For more details on the hydrodynamic load model for nets in FhSim, see Enerhaug et al (2012). The wake effect, meaning the reduction of incident water velocity due to blockage from upstream parts of the net is also included in the hydrodynamic load model in FhSim.…”

Section: Theorymentioning

confidence: 99%

“…Previously, the net model had been used to simulate net panels with rhombic meshes (Enerhaug et al, 2012), net panels with bending stiffness Jensen et al, 2013), and a variety of cylindrical net cages of smaller dimensions (Moe-Føre et al, 2014). The structural model of the net is based on Priour (1999Priour ( , 2001Priour ( , 2003.…”

Section: Theorymentioning

confidence: 99%

See 2 more Smart Citations

Three-dimensional deformation of a large circular flexible sea cage in high currents: Field experiment and modeling

Klebert

Patursson²,

Endresen

et al. 2015

Ocean Engineering

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Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

See 1 more Smart Citation

Three-dimensional deformation of a large circular flexible sea cage in high currents: Field experiment and modeling

Klebert

Patursson²,

Endresen

et al. 2015

Ocean Engineering

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“…[17]) to model arbitrary net structures [18,19]. Numerical models of the copper and PET net panels were realized in FhSim, which is a framework for numerical time-domain simulation developed at SINTEF Fish eries and Aquaculture.…”

Section: Methodsmentioning

confidence: 99%

Deformation of Nets With Bending Stiffness Normal To Uniform Currents

Gansel

Jensen

Endresen

et al. 2014

Journal of Offshore Mechanics and Arctic Engineering

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The tremendous growth o f the fishfarming industry in Norway over the past decades was supported by new designs and materials fo r fish farms, enabling bigger fish cages to be positioned in more exposed sea areas. Today, the nets o f most fish cages in Norway are made from nylon, but also new net materials are proposed to better prevent escapes, pro tect fish from predator attacks, improve the stability offish cages, and reduce biofouling. Some o f these materials are stiff in at least one direction, and there still is a lack o f knowledge about the behavior o f nets with bending stiffness in currents and waves. The aim o f this study was to determine how nets with bending stiffness deform in differen t cur rents and how the deformation influences the drag on the nets and to compare the results with predictions from a numerical model. Three types o f net (PET, copper, and steel) were clamped to a solid steel bar on the top side but were otherwise unrestricted. The nets were subjected to several flow speeds between 0.1 and 0.9 mis. The net deformation was determined with an optical tracking system, and the forces on the net panels were measured with a multi-axis force! torque sensor system. It is shown that bending stiffness and density o f nets affect net deformation, as both parameters impact the balance between drag and gravitational forces on the nets. Net deformation leads to a decrease o f the projected net area. As the rate o f deformation with current speed varies greatly between different net types, the discrepancy between measured drag and drag values nor malized to the projected net area at different current speeds follows different relation ships fo r different nets. A numerical model, FhSim, was able to predict net deformation o f nets with bending stiffness well, and it is shown thatFhSim could not only account fo r the effect o f bending stiffness on net deformation, but also that the model captures the structural dynamics o f nets with bending stiffness in a current. J ou rn al of O ffs h o re M ech an ics and A rctic E n g in eering C o p y rig h t© T a b le 2 O v e r v ie w o v e r f lo w s p e e d s t h e n e t s a n d m o u n t s w e r e s u b je c t e d to

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“…These phases are described in detail in sections 2.1 and 2.2. Although 3D effects such as wakes (Endersen et al 2013;Enerhaug et al 2012) are not discussed in this study, their influence can be included by modifying the hydrodynamic force database built in the first phase. Meanwhile, all fish farming systems are constructed with interconnected net sections, so their hydroelastic response can always be modeled using the proposed hybrid method.…”

Section: Hybrid Empirical-numerical Analysismentioning

confidence: 99%

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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Current Loads on Net Panels With Rhombic Meshes

Cited by 8 publications

References 0 publications

Three-dimensional deformation of a large circular flexible sea cage in high currents: Field experiment and modeling

Three-dimensional deformation of a large circular flexible sea cage in high currents: Field experiment and modeling

Deformation of Nets With Bending Stiffness Normal To Uniform Currents

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

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