Numerical Study on the Flow Field Around a Fish Farm in Tidal Current

The netting of the fish farm, with biofouling or not, was simulated using the porous-media fluid model. The porouscoefficients for both clean and biofouled netting were calculated from the drag and lift forces that acts on corresponding cleanor biofouled plane net, consequently the relationship between the porous coefficients and the features of the netting as well asthe biofouling is established. In this study, both constant and tidal currents through a fish farm, consisting of 2×4 full-scale netcages, were investigated numerically. Effects of cage height, incidence angle of the current and level of biofouling on thenetting on the flow field in vicinity region of the fish farm were presented and discussed. Compared with constant current,tidal current produces different flow pattern downstream from the fish farm. Overall, the height of the wake regiondownstream from the fish farm increases with increasing cage height. The attenuation in flow velocity both inside the net cageand in the wake region increases as the level of biofouling increases. With respect to the incidence angle of the tidal current,the optimal orientation of the fish farm can be determined in certain tidal current from an ecological perspective.

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