框架型与沉箱型人工鱼礁绕流特性的数值模拟

Numerical simulation of flow around frame and caisson artificial reef models

为对框架型(正六面柱形罩式边长为2 m、高4 m)和沉箱型(方形空心开口式3 m×3 m)人工鱼礁模型绕流特性进行分析,采用Computational Fluid Dynamics(CFD)方法研究了礁体周围的流线分布变化及上升流和背涡流的流态变化情况。结果表明:在礁体内部,框架型礁体的涡旋在底部出现,沉箱型礁体的涡旋在底部及中部出现,且沉箱型礁体涡旋范围大于框架型礁体;框架型背涡区压强空间分布较为均匀,而沉箱型外侧左右两端有0.5倍礁宽的压强变化,背涡区压强空间分布不均匀;沉箱型礁体在0.5～1.0倍高度上升流区域流速增大。研究表明,相同工况下综合比较框架型产生的流场效应更优,能更好地发挥鱼礁的集鱼效果。

Changes in flow branch and regime and upwelling were investigated in frame type(bell type of six columnar plane 2 m×4 m)and caisson(hollow opening square 3 m×3 m)artificial reefs to analyze the flow characteristics around the artificial reefs by Computational Fluid Dynamics (CFD) method. The results showed that the vortex was found at the bottom of the frame type reef, and at the bottom and the middle part in the caisson reef, larger in the caisson reef than that in the frame type reef. There was uniform spatial distribution of pressure in the frame type back vortex region, and change in 0.5 times pressure was observed in reef wide in the left and right sides of the caisson type reef, with uneven pressure spatial distribution in back vortex area of the caisson type. The velocity was found to be increased at the 0.5-1.0 times height of upwelling area in the caisson reef. The comprehensive comparison indicates that the frame type reef has good flow field effect, and high efficiency in fish collecting under the same working conditions.