Experimental Investigation on Hydrodynamic Coefficients of a Column-Stabilized Fish Cage in Waves

Zhao Zhao,Chen Chen,Cui Cui,Bi Bi

doi:10.3390/jmse7110418

Abstract

This study on hydrodynamic coefficients of a column-stabilized fish cage under wave action plays an important role in the anti-wave design of cages. The regular wave test was used to study the horizontal wave force of the jacket and column-stabilized fish cage under different wave heights, periods, and incident angles; the finite element model of the jacket and the column-stabilized fish cage was established according to the test model. On the basis of the calculation of the finite element model, combined with the wave force obtained from the experiment, the hydrodynamic coefficients of the structure was fitted by the least squares method, and then the drag force, inertial force, and total force of the structure under different conditions were calculated. The results show that the hydrodynamic coefficients of the jacket and netting under the wave condition were more obvious with the change of the KC number and wave incident angles. And as the wave height increased, the drag force, the inertial force, and the proportion of the drag force to the horizontal wave force both increased. When the wavelength was large, the same trend occured as the wave period increased. When the wave incident angles were different, the forces of the jacket and the column-stabilized fish cage were always small in lateral low-frequency waves, which is consistent with the change law of hydrodynamic coefficients of the jacket and netting.

Highlights

There are developments made almost daily in marine aquaculture equipment in China. One such development is that of column-stabilized fish cages, which have gradually been recognized because of their structure safety, steadfast and reliable, and convenient integration with other marine jacket platforms
The results indicate that there was a peak phase difference between the drag force and the inertial force that make up the wave force, and the peak phase of the inertial force was before the total force, while the peak phase of the drag force was after the total force, which were determined by Equations (2) and (3)
The total upstream area was large, due to the severe shielding of the members on the meeting-wave side, the force of the subsequent members was significantly reduced, which directly led to the reduction of the total oblique waves, while the horizontal wave force under the lateral wave was smaller

Summary

Introduction

There are developments made almost daily in marine aquaculture equipment in China One such development is that of column-stabilized fish cages, which have gradually been recognized because of their structure safety, steadfast and reliable, and convenient integration with other marine jacket platforms. As the coastal environment is deteriorating, aquaculture is gradually developing into more open sea; there are a large number of abandoned or newly developed jacket platforms, such as developing oil and wind energy. Combining this jacket structure with the netting structure improves the capacity of anti-storm of the deep sea cage, and effectively solves the power supply problem of the breeding equipment, and facilitates the automation and intelligence of the deep sea aquaculture industry. It is necessary to carry out relevant experiments to study the force and hydrodynamic coefficients law of the column-stable cage under regular waves

Results

Discussion

Conclusion