HYDRODYNAMIC ANALYSIS OF GRAVITY NET CAGE IN OPEN SEA

Resumo

This work is orientated towards modeling the hydrodinamic response of a circular net cage for fish-
farming, submitted to the wave conditions of the city of Rio Grande - Rio Grande do Sul (RS). For this purpose,

several routines were created using the MATLAB program, in order to determine the hydrostatic equilibrium of the
structure, the drag force acting on the cage’s net and the mooring systems using different materials. In possession
of given data and taking into account the wave regimes of the study site, simulations were performed using the
ANSYS AQWA software in order to obtain the cable tensions and the net cage behavior. Thereby, it can be noted
that the break strength of the mooring system cables was not exceeded and the mooring systems were effective
to keep the structure stable. At last, the modeling of the drag force acting on the net with the software used,
by applying the drag coefficient formula, proved to be an acceptable solution for questions involving net cage.
However, it is important to emphasize that the model used does not consider the non-linearity of the net. Also, the
study suggests the installation of a smaller diameter net cage for pisciculture at the study site.