Hydrodynamics And Numerical Simulation Of Artificial Reefs

An artificial reef is one or more objects of natural or human origin deployed purposefully on the seafloor to influence physical, biological, or socioeconomic processes related to living marine resources, and it is the important component of the construction of marine ranching engineering. Just like other ocean engineering structures, artificial reefs on sea bottom are withstood by the hydrological environment effects responded by the current conditions, and then the perspective of flow field effect and forces stood are nearly correlated with theirs hydrodynamic capability under the ocean field conditions. About the studies of the hydrodynamic capability of artificial reef, researchers usually recur to the reference of traditional fishing gear hydrodynamics and flume tank experiments. However, these methods may be affected or limited by theoretical profundity, fluid attributes, meterage methods and precision, manpower and material resources, etc, which can't meet the requirement of complete understanding for the hydrodynamics of artificial reef.This paper, aimed at artificial reef model, according as computational fluid dynamics, based on the Fluent CFD code, utilized three-dimensional turbulent model to simulate the hydrodynamic capability of artificial reef models. The pressure distribution, flow field effect and forces stood of model reefs are obtained, which shows the flow field structure on the locals of artificial reefs. A good agreement is achieved between numerical results with flume tank experiments data, especially, the particle imagine velocimetry data. It suggested that the numerical simulation method adopted in this paper can be applied to predict the hydrodynamic capability of artificial reefs, and then popularize this method in the study of actual artificial reef. Its achievement will establish the theoretical foundation for the pilot study of artificial reef flow field theory and designs optimized, and supply the scientific reference to the progressive development of layout and construction of artificial reef areas.Firstly, a numerical simulation model of RNG k -εturbulent flow aimed at apertured cube artificial reef model is established in this paper. By use of this numerical model, the three-dimensional flow structure is predicted; the relationship between pressure and velocity is analyzed; and the values of forces stood and velocities are obtained. Numerical results have a good coherence compared with experiments data; the relative errors between the numerical and metrical are all small, which are in range of 2.3 %~26.2 % and 1.3 %~36.4 % respectively. It suggested that both the numerical and experimental methods could represent the increase trends of forces stood with the flow velocities increasing, and numerical results are basically accorded with the flow field characteristic of cross flow past the locals of model reef.Secondly, aimed at a single apertured cube artificial reef model, three-dimensional turbulent model is applied to simulate the unsteady flow of cross flow; simultaneous, by the PIV technology, the flow characteristic on the longitudinal central section of flow field of cross flow pasting the artificial reef model is measured, and the dynamic process of the vortex alternative formation, its development and extinction are realize clearly, where are in the upstream, the wake, the front, the inside areas respectively. Numerical results have a good coherence compared with PIV data, which agrees with the flow structure on the locals of artificial reef model and the forces stood by model.Thirdly, by three-dimensional numerical simulation technology, the unsteady flow of cross flow past a trapezoid platform artificial reef model is simulated, and the flow field effect of trapezoid platform reef model is realized. Numerical results have a good coherence compared with PIV data. These results can more indicate that both the numerical computation and characteristic predictions in this paper achieve a precision to some extent. And the incidence of upwelling and flow field were compare within three kind of artificial reef model.Finally, based on computational fluid dynamics theory, three-dimensional turbulent model is adopted to simulate the flow in artificial reef block, and flow field distribution in block of artificial reef ecosystem. It is feasible for people to realize the flow field effect of artificial reef block intuitively, and then supply scientific reference to the layout and construction of artificial reef areas.