Abstract: The long-line abalone culture system in the bottom waters outside the bay is a new type of aquaculture facility, which utilises the attenuation effect of waves underwater to achieve better resistance to wind and waves. Currently, most of the research on longline aquaculture systems is aimed at the sea surface, and the research on the seabed is still pending. Therefore, in order to ensure the survival rate and structural safety of the abalone culture system, it is of great significance to study the dynamic characteristics of the long-line abalone culture system in the bottom waters. Based on the similarity criterion, a model test was carried out in the wave current flume laboratory; based on the centralised mass model, a numerical simulation method of the dynamic response of the long-line abalone culture system in the bottom waters was established, and the accuracy of the numerical simulation method was verified; in view of the actual sea conditions off Luoyuan Bay, Fujian Province, the dynamic characteristics of the long-line abalone culture system in the bottom waters were numerically simulated under the action of different waves and currents to analyse the effects of the wave heights, current velocities and flow directions on the stresses on the abalone culture system and the structural safety of the system. The effects of wave height, current speed and flow direction on the force and trajectory of the system were analysed. The results show that: the numerical model is consistent with the model test results, the maximum relative error of the maximum cable tension measured against the waves is 8.33%, the minimum relative error is 4.84%, and the average relative error of the peak horizontal and vertical motions of the float A is 5.23% and 8.92% respectively, which proves that the numerical simulation method used in this paper is accurate and reliable; there is a significant difference in the distribution of the force of the longline and the anchor rope, and the force curve of the longline shows an arch of the force. The force distribution of the longline and the anchor rope has obvious differences, the force curve of the longline shows an arch shape and a sawtooth shape, and the maximum force section is not on the anchor rope, but located in the middle region of the longline; the wave height has a linear relationship with the maximum force of the system and the motion amplitude of the abalone cage, i.e., the higher the wave height is, the larger the transverse and vertical motion amplitude of the system is, and the larger the maximum tension in the middle part of the longline, the supporting rope and the anchor rope is, and the peak tension curve of the supporting rope shows a sawtooth shape; the maximum tension of the anchor rope in the headward side appears nonlinearly when the velocity of the current is increasing, the maximum tension of the anchor rope in the headward side appears nonlinearly. When the flow velocity increases, the maximum tension of the anchor rope on the headwater side shows a nonlinear steep increase, the maximum tension of the longline on the headwater side increases slowly, the maximum tension of the anchor rope and the longline on the backwater side decreases significantly, while the maximum tension of the branch ropes does not increase significantly with the flow velocity, and the maximum tension of each branch rope is the same; when the flow direction increases, the maximum tension of the system's anterior part of the longline and the anchor rope decreases, and that of the posterior part of the longline and the anchor rope increases, and the branch ropes' tensions basically remain relatively stable. The results of this study can provide a reference for the structural design of similar long-line abalone culture system in the bottom waters.

Key words: Long-line abalone culture system in the bottom waters, Lumped mass method, Numerical simulation, Model test, Hydrodynamic characteristic

摘要： 湾外底层延绳式养鲍系统是一种新型养殖设施，利用波浪在水下的衰减效应，实现较好的抗风浪性能，为了确保养鲍系统的存活率和结构安全性，研究延绳式养鲍系统的动力特性具有重要意义。基于相似准则，在波流水槽实验室开展了模型试验；基于集中质量模型，建立了底层延绳式养鲍系统动力响应数值模拟方法，验证了数值模拟方法的准确性；针对福建省罗源湾外实际海况，在不同的波浪及海流作用下，对底层延绳式养鲍系统的动力特性进行数值模拟，分析了波高、流速及流向对养鲍系统受力情况及运动轨迹的影响。结果显示：梗绳和锚绳的受力分布存在明显差异，最大受力段不在锚绳上，而是位于梗绳中部区域；波高与系统最大受力和鲍鱼笼的运动幅值近似呈线性关系；当流速增大时，迎流侧锚绳的张力出现非线性陡增，背流侧锚绳的张力明显减小；当流向角度增大时，系统前部梗绳的张力减小，支绳张力基本保持相对稳定。该研究结果可为类似底层延绳式养鲍系统的结构设计提供参考。

关键词: 底层延绳式养鲍系统, 集中质量法, 数值模拟, 模型试验, 水动力特性