Study On The Hydrodynamic Characteristics Of Functional Artificial Reef

The marine fishery resource is declined rapidly due to environmental degradation andover-fishing. The theme of ocean management in the21st century is sustainabledevelopment. As a new system for mariculture and enhancement, the marine ranchingplays a very important role. And artificial reef is the key part of the marine ranching, itrepairs ecological environment and also protects and enhances aquatic resources. Theartificial reef progress is comparatively in lower level in our country, mostly we observeand absorb advanced technologies from other countries.In this paper, we designed a new functional artificial reef, which was combined withthe light control. The contents are mainly composed of three parts:In the first part, we designed the new functional artificial reef, combining the reefwith tidal current energy. We determined the size and materials of the constructs.The second part is about the hydrodynamic behaviors of artificial reef, including thedrag coefficient and the flow field around artificial reef. We find that, for the reef withouthole on the top, when the angle of current attack is0°and45°, the drag coefficient is1.41and1.63. Otherwise, the drag coefficient is1.46and1.53. By the value of C_dwe got, Wealso studyed the stability of the reef. It shows that, the reef will not slide or rolling even thevelocity up to1.2m/s. Determining the flow field around the reef, we obtain that there’s noobvious difference of the upwelling area、eddy field behind reefs and flow regime regionbehind reefs scale at different velocities. We also conduct a streamline visualization of reefexperiment, which is much more intuitional.In the third part, the attractive effects of the artificial reef model with different lightcolors on Sebastiscus marmoratus and Argyrosomus japonicas were studied throughexperimental tests. The results showed that the attraction rate in the artificial reef areaunder the natural light condition was higher than other five groups. Light color hassignificant effect on the attraction rate which ranks from low to high as: Orange group <Green group <Red group <Blue group <White group <Natural group. Therefore, we candraw a preliminary conclusion that Sebastiscus marmoratus has a negative phototaxis. As for the Argyrosomus japonicas, there was no obvious aggregation phenomenon was foundin the artificial reef area during the experiment. We may also draw a conclusion that lightcolor has no effect on the attraction rate as there is no significant difference among thenatural group and other five light groups.