方形人工鱼礁通透性及其对礁体周围流场影响的数值实验

基于考虑不同形状大小、组合规模的人工鱼礁投放于不同水域环境后形成的流态变化有较大差异,设计x、y、z三个方向不同通透方式的单个正方体人工鱼礁,采用LES(大涡模拟)紊流模式,对定常来流速度下人工鱼礁单体附近流场进行三维数值模拟,建立反映礁体结构的通透系数与礁体产生流场变化的关系。结果显示:上升流和背涡流的规模随通透系数增加而减小;来流方向上,礁体迎流面、背流面的通透系数变化对上升流和背涡流规模影响较为显著,而内部结构的变化则作用不明显,礁体上方与侧方的开口对上升流和背涡流的影响也不显著。迎流面通透系数变化是背涡流规模影响的主要因素。方形单礁缓流区体积随通透系数Tin增大呈线性减小,关系为V_x=-1241.8T_in+1206。通过该研究可在数值计算中通过通透系数与流场变化的关系,实现将复杂礁体简单化,有效地提高计算效率;为将小范围模拟扩大到群礁、甚至大海域的模拟,定量评估人工鱼礁的生态效应打下基础。

The numerical experiment on the permeability of a cubic artificial reef and the effect on the flow field around the reef

Different shapes,sizes,and the combinations of the artificial reefs can affect the upwelling and the back eddy flow.Considering the artificial reef in the sea can cause certain alteration to the flow around it,by using the Large Eddy Simulation (LES), a method of Computational Fluid Dynamics,this paper tries to design different structures of a cubic reef through x /y /z three directions,then we can study the connection between the structures and permeability.The result showed that the ranges of the upwelling and back eddy flows decreased as the increase of input and back-output permeability strongly;but the effect from the permeability of internal structure and the permeability of direction y and z are not very clear.So the InputPermeability is the main effect factor of the range of the back eddy flows.The volume of the back eddy flows around a cubic artificial reef decreases as the increase of the Permeability T_m,the equation is V_x=-1241.8T_m + 1206.According to this study,we can use the relation between the permeability and the change of the flows;so that we can simplify the reef with complex structure in the 3D numerical simulation as well as the improvement of computed speed;Based on this research,we can apply the small range simulation to the large area in order to evaluate the ecological effect of artificial reef.