Abstract: A positive six prism type artificial reef was designed to improve the marine fisheries habitat of the Zhoushan Archipelago. Two parameters of ε and η were used to evaluate the structure of artificial reefs, the value ε reflects the water permeability of artificial reefs and the value η reflects the adhesion ability of artificial reefs. The positive six prism type artificial reef was found to have a good permeability, and could also provide a larger area for the attachment of marine organisms. The design objectives were met. Based on the Fluent software, the CFD simulation of the fish reef was carried out, it was found that the maximum height of the upwelling increased with the flow velocity, and the length of the back vortex was about 9.3-9.6 times of the height of the fish reef, which indicated that it had a good hydrodynamic performance. In order to validate the performance of simulation further, flume experiment was conducted, which yielded consistent results as the simulation study. This further proved the validity of the hydrodynamic performance of the positive six prism artificial reef. The field experiment was also conducted at the end to evaluate the effect of the positive six prism reefs and to compare with the regular artificial reefs. Both the reefs could improve marine environment, but the average of density and biomass in the area of the positive six prism type artificial reef was higher than those in the control reef area, showing that the positive six prism artificial reef tended to have better hydrodynamic characteristics leading to more efficient in improving local habitats.

Key words: artificial reef, upwelling current, wake vortex, CFD simulation, flume experiment, effect evaluation