Artificial reefs are beneficial to restore fishery resources and increase fishery production. Meanwhile, they play a significant role in improving ocean ecology and accelerating the evolution of fishery industries. Since they are generally affected by currents, waves, and other hydrological factors, the flow field around artificial reefs and their stabilities have become a research hotspot in recent years. Research on artificial reefs is a systematic process consisting of four aspects: Firstly, the significance, the definition, the mechanism, and the present research progress were introduced for artificial reefs in detail. Secondly, the development trend of the sit-bottom artificial reef and that of the floating artificial reef were summarized, respectively. Thirdly, it was found that the combination of traditional artificial reefs and emerging ocean engineering has a great development potential in practical engineering. Finally, the existing problems related to the hydrodynamic characteristics of the artificial reefs in China were summarized, and the prospects of artificial reefs were proposed. The purpose of this study is to provide a scientific reference for the ecological and sustainable development of the large-scale construction of artificial reefs in the ocean.

An artificial floating reef is an important part of the coastal ecological corridor. The large-scale construction of floating reefs by optimizing mooring methods can effectively improve the ecological effects of coastal projects. The artificial floating reef belongs to coastal engineering, and wave resistance is fundamental to its structural design. In this paper, the method for processing coupling forces and motion, the method for judging the floating reef out of water surface, and the method for correcting velocity and acceleration of water mass points are elaborated in detail by using the finite element method and lumped-mass mooring model. By comparing and analyzing the results of physical experiment and numerical simulation, the correctness of the numerical model is verified. Finally, the diachronic variation of pitching angle of floating reef, the tension of the mooring rope, and the total tension of the fixed points of the fishing net were analyzed by the dynamic response numerical mode with a new type of mooring. The purpose of the current study was to provide a basis for the optimization of structure shape, the matching of floating body, and the counterweight of artificial floating reef.

The possibility of using microvortex generator jets to improve the flight stability and firing accuracy of the M549 projectile by regulating the vortex distribution on the surface is studied in this paper. The microvortex generator jet is inserted in front of the projectile shoulder, and the flow field structure around the projectile is simulated by the detached eddy simulation method. The numerical results show that microvortex generator jets can eliminate irregular vibrations induced by aerodynamics forces by inhibiting vortex shedding.

Artificial floating reefs are an important supplement to bottom reefs in marine habitat construction, which provide a good environment for fish to survive, breed and habituate in the middle and upper layers of water. They can adapt to the silt bottom of the East China Sea. To make full use of the water space and improve the effective space of the floating reef, based on the field tidal current data, an upper- and lower-layered artificial floating reef has been designed in this study. The connection method of the upper and lower reefs has been described in detail and a hydrodynamic numerical model has been established. At the same time, the effects of floating reef structure ratio, wave height and wave steepness on its force and motion are discussed under the action of tidal current and wave current. The result shows that, at a specific flow rate, the change of the proportion of the layered floating reef structure had little effect on the roll of the upper and lower reefs. The maximum roll angle does not exceed 15°, and the tilt angle of the upper and lower reefs is consistent, which ensures the good flow resistance and stability of the floating reef. Under the specific length of the connecting cable and the main mooring, the hydrodynamic characteristics of the layered floating reef are better when the ratio of the sum height of the lower reef and the connecting cable to the height of the upper reef is not greater than one and the extreme proportion structure is not considered. The tension of the stratified floating reef is proportional to the wave height and wave steepness under the action of wave and current. The main mooring rope is the most stressed, and the rolling motion of the upper and lower reefs is consistent. Above all, results can provide a theoretical basis for the optimization design of the artificial floating reef structure.