考虑多因素的多网箱水动力分析

Multifactor Hydrodynamic Analysis of Multiple Fish Cages

摘要:

为揭示深远海网箱养殖系统中多因素耦合作用下水动力特性，基于计算流体力学（CFD）方法，建立了考虑网衣结构、鱼体阻力及泥沙颗粒作用的多孔介质模型，开展了单网箱、双网箱及3×3多网箱阵列的流场数值模拟研究。结果表明，网衣主导流场分布，鱼体强化尾流衰减，泥沙调控尾流恢复过程。单网箱条件下流场呈“上游减速-内部低速-下游尾流”的典型结构，网衣为主导因素，使内部流速降低10%~18%;鱼体通过阻塞效应增强流速衰减并延长尾流恢复距离至约6D;泥沙颗粒通过颗粒-流体动量交换调制尾流区湍流结构，在增强整体衰减的同时诱导局部再加速现象。双网箱系统中存在明显尾流遮蔽效应，且网箱间距对尾流干扰具有显著影响，当间距由1.5D增大至3D时，尾流长度由40~50 m缩短至20~25 m。多网箱阵列中尾流叠加效应进一步增强，交叉排列可使下游流速提高6%~10%，改善流场均匀性;当网箱间距不小于2.5D时，尾流干扰明显减弱，阵列流场趋于稳定，水体交换能力得到有效改善。在多因素耦合作用下，阵列流速衰减率为18%~24%，为深远海网箱布局优化、水体交换能力提升及养殖环境调控提供理论依据与技术参考。

Abstract:

Aiming to investigate the hydrodynamic characteristics of offshore aquaculture cage systems under multi-factor coupling, a computational fluid dynamics (CFD) model was developed incorporating net structure, fish-induced resistance, and sediment particle effects by using a porous media approach. Simulations were performed for single, double, and 3×3 cage array configurations. Results showed that the single-cage flow field exhibited a typical pattern of upstream deceleration, internal low velocity, and downstream wake. The net structure dominated the flow, reducing internal velocity by 10%~18%. Fish further increased flow resistance, enhanced velocity attenuation, and extended the wake recovery distance to about 6D. Sediment particles modified the wake through particle-fluid momentum exchange, enhancing turbulence and inducing local re-acceleration. In double-cage systems, while increasing spacing from 1.5D to 3D, shortened the wake length from 40~50 m to 20~25 m. In cage arrays, wake superposition intensified, whereas staggered arrangements improved flow uniformity and increased downstream velocity by 6%~10%, with a minimum inter-cage clearance of 2.5D, the wake interference effect was rendered negligible, the surrounding flow field attained a quasi-equilibrium configuration, and the mass transfer between the internal and external water bodies was significantly facilitated. Overall, netting governed flow distribution, fish enhanced attenuation, and sediment regulated wake recovery. The research result can provide a quantitative framework for optimizing cage layout and hydrodynamic conditions in offshore aquaculture.