Abstract: It is an important work to study the hydrodynamic characteristics of the net structure to guarantee the safety of the whole net cage system in deep open sea. The most widely used copper alloy net in aquaculture cages is of the “chain-link” type mental net, which is a kind of porous structure with a small diameter, whose hydrodynamic characteristics under the waves and currents is significantly different from general ocean engineering structures. Based on the finite element method, the chain-link nets and the interaction between them are simulated by the beam element and connector element in the ABAQUS software. After verification by the experiment data, the different flow resistances on the net under currents with different net diameters and mesh sizes were analyzed. The numerical simulation results showed that as the mesh size increases from 25mm, 35mm to 45mm, the average value of the flow resistance increases with the amplification of 14.71% and 38.07% respectively under various operating modes. Similarly, the average value of flow resistance increases with the amplification of 25.05% and 45.06% respectively under various operating modes as the net diameter increases from 2.5mm, 3.2mm to 4.0mm. The research provides a positive foundation for further study of the hydrodynamic characteristics of deep-sea aquaculture metal cages.

Key words: metal net, flow resistance characteristics, beam element, connector element, numerical simulation

摘要： 为保障深远海金属网箱养殖系统的结构安全，进行网箱结构的水动力学研究是一项重要的工作。构成金属网箱主要组成部分的金属网衣是一种小直径多孔的网状结构，在波浪和水流作用下的水动力学特性与一般的海洋工程结构物有显著不同。本文基于有限元基本原理，采用梁单元模拟金属网线结构，采用连接单元模拟网线接触部位的相互作用，并运用ABAQUS软件进行数值计算，在试验验证的基础上，分析了在水流作用下一种金属菱形链网衣在不同网目尺寸、不同网线直径情况下的水阻力变化情况。数值模拟结果表明在各种工况下，当网目尺寸由25mm增加到35mm、45mm时，网衣受力增加幅度的平均值分别为14.71%和38.07%；当网线直径由2.5mm增加到3.2mm、4.0mm时，各工况下网衣受力增加幅度的平均值分别为25.05%和45.06%。研究结果可以为进一步开展深海养殖金属网箱水动力特性研究提供积极的基础。

关键词: 金属网衣, 水阻力特性, 梁单元, 连接单元, 数值模拟