Abstract
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.
Highlights
Fish farming provides an important protein supply for humans and brings huge economic benefits
The dynamic behaviour of fish cage nets is simulated by numerical models, for example, the bar element model in [4,5] or mass-spring model in [6,7], in which the hydrodynamic force on each element is estimated by the Morison equation or the screen-type method proposed by [8]
The net cage is modelled as a flexible porous cylinder and its wave actions
Summary
Fish farming provides an important protein supply for humans and brings huge economic benefits. The dynamic behaviour of fish cage nets is simulated by numerical models, for example, the bar element model in [4,5] or mass-spring model in [6,7], in which the hydrodynamic force on each element is estimated by the Morison equation or the screen-type method proposed by [8] These models neglect the interferences of the structure and its motions on the flow field. The interactions between waves and submersible cylindrical fish net cage are approximated by a semi-analytical solution based on linear hydroelastic theory.
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