不同布设间距下方型人工鱼礁体的水动力特性数值研究

为研究方型人工鱼礁体水动力特性受礁体布设间距变化的影响,通过物模实验实测了开口比为0.3的方形开口双礁体在布设间距为1.0L、2.0L时周围特征点的流速及礁体受力,并利用Fluent软件模拟了双礁体在布设间距为0.5L、1.0L、2.0L、4.0L时的水动力场,通过分析得到了礁体上升流特性参数、阻力系数随布设间距的变化情况。研究结果表明:数值模拟结果与实验结果吻合较好,本文数值模拟方法是可行的;模拟工况下,随着布设间距的增加,双礁体产生的上升流区体积逐渐减小,阻力系数逐渐增大,流场效应较好的布设间距为0.5L、1.0L、2.0L。研究结果可为礁区布局方案的确定提供参考。

Numerical Research on Hydrodynamic Characteristics of Artificial Reefs with Different Disposal Spaces

With the improvement of the living standard and the decline of offshore marine fishery resources, restoring the ecological environment of the offshore waters, protecting fishery resources and maintaining the sustainable development of marine fisheries are becoming an urgent task at present. Therefore, some scholars proposed the idea of constructing artificial reefs a few decades ago. Artificial reefs are an important part of the construction of marine pastures. They are one or more natural or artificial structures placed purposefully on the seabed, which have a positive impact on the physical, biological or socio-economic processes related to marine living resources. For the present, the artificial reef is becoming a new increasing point of marine fishery and develops rapidly in the world.In order to research the effect of disposal spaces on the hydrodynamic characteristics of square-type artificial reefs, the measuring points’ velocities and the force on reefs are measured through physical model test when the disposal spaces are 1.0L and 2.0L, and the three-dimensional CFD simulation software-FLUENT is applied to study the flow fields of artificial reefs with 0.3 opening ratio under different disposal spaces(0.5L^4.0L), the variation of the flow field effect and drag coefficients of reefs with different disposal spaces is obtained through analyzing the variation laws of the flow fields.In this paper, the velocity and force value of the measured points of the reefs by numerical simulation are in good agreement with the measured values of physical model experiment. It is proved that the calculation method adopted in this paper is feasible. The following results are then obtained from the simulation:(1) The hydrodynamic characteristics presented a few differences with the different disposal spaces. Under the simulating operating conditions, the volume of upwelling reduces with the increase of disposal spaces, but the volume of slow-flow area and k_Z all increase.(2) The formula for the k_z of the double cubic reefs under different disposal spaces is: k_z=0.003 5×(D/L)~2+0.038(D/L)+0.11(R^2=0.97). The optimum disposal space is 0.5L^2.0L. The results of the research can provide references for determination of reef areas’ layouts.(3) When the two reefs are set with spacing of 0.5L along the direction of the current, the characteristic parameter of upwelling is the largest. When the two reefs are set with spacing of 2.0L along the direction of the current, the maximum influencing range of the slow flow area is the most extensive. It can be seen that the flow field effects are stronger when the disposal spaces are 0.5L^2.0L. The obtained results of this paper have some engineering application values and can provide reference for the determination of reef areas’ layouts.