人工鱼礁结构设计原理与研究进展

为了解侧板结构对八棱柱型人工鱼礁流场效应的影响，实验基于计算流体力学方法 (computational fluid dynamics, CFD)，利用大涡模拟 (LES)对4种不同侧板结构的八棱柱型人工鱼礁周围流场变化进行数值模拟，并以上升流体积、背涡流体积和向上输运通量等为流场效应指标进行了分析，同时利用水槽实验对数值模型进行验证。结果显示，水槽实验流速与2种尺寸数值模拟流速的均方根误差最大不超过0.065。0°垂直迎流时，2种来流速度下，A型、C型和D型礁的上升流体积较B型礁最大分别高35.6%、244.1%和80.1%，背涡流体积较B型礁最大分别高193.5%、115.8%和88.8%。C型和D型礁的向上输运通量均大于A型礁，且C型礁最大向上输运通量是D型礁的1.29倍。不同迎流角度下，C型礁和D型礁的上升流体积和背涡流体积在4种角度下差异显著，且迎流面投影面积和上升流体积及背涡流体积之间相关系数较小。研究表明，实验所采用的数值模拟准确可靠；侧板数量增加对于提升八棱柱型人工鱼礁流场效应尤其是上升流效应作用明显；下层侧板固定时，上层为倾斜侧板有利于提升礁体的上升流效应，上层为垂直侧板时有利于提升礁体的背涡流效应；不同的侧板组合会影响礁体对迎流角度的适应性。本研究结果可为鱼礁单体的优化设计以及大尺度海洋数值模型中阻力参数设定提供参考。

Comparison of artificial and natural reef productivity in Nantucket Sound,MA, USA

In order to understand the influence of the side plate structure on the flow field effect of the octagonal prism artificial reef, this paper is based on the computational fluid dynamics method (CFD), using large eddy simulation (LES) to analyze the octagonal prism type of four different side plate structures. The changes of the flow field around the artificial reef are numerically simulated. And the flow field effect indicators are analyzed with the volume of upwelling, the volume of wake vortex and upward transport flux. At the same time, the numerical model was verified by the water tank experiment. The results show that the maximum root-mean-square error between the experimental flow velocity of the flume and the numerical simulation flow velocity of the two sizes does not exceed 0.065. At 0° vertical upstream, the upwelling volume of type A, type C and type D reef is 35.6%, 244.1% and 80.1% higher than that of type B reef, and the volume of wake vortex is 193.5%, 115.8% and 88.8% higher than that of type B reef, respectively. The upward transport flux of type C and type D is greater than that of type A, and the maximum upward transportation flux of type C is 1.29 times that of type D. At different upstream angles, the correlation between the projected area of upstream surface and the volume of upwelling of types C and D is obvious, and that between the projected area of upstream surface and the volume of wake vortex of types C and D was small. The research results indicate that: the numerical simulation used in this paper is accurate and reliable. The increase in the number of side plates has a significant effect on improving the flow field effect of the octagonal prism artificial reef, especially the upwelling effect. When the lower side plate is fixed, the inclined side plate of the upper layer is helpful to enhance the upwelling effect of the reef, and the vertical side plate of the upper layer is helpful to enhance the wake vortex effect of the reef, and different side plate combinations will cause different flow field effects. The research results can provide a reference for the optimal design of reef cell and the setting of relevant retarding parameters in large-scale marine numerical models.