Abstract This paper presents a design concept of a porous collar barrier for a novel floating open-net fish cage that is integrated with a floating spar wind turbine (referred to as COSPAR fish cage). The COSPAR fish cage has an octagonal shape with each side length of 30m. The collar barrier, having an array of rectangular cut-outs with round corners, is installed at the top portion of the cage to attenuate wave transmission inside the cage as well as to protect fish from external predators and debris. Single and double collar barrier designs corresponding to single net and double net cages are studied. The wave transmission, reflection and energy-loss coefficients of barriers are determined from numerical analysis based on the linear potential wave theory and the eigenfunction expansion method. Various underwater heights (2m ≤ h ≤ 8m) and porosity (0.25≤ e≤ 0.75) of the collar barriers are examined with the view to obtaining the barrier design for minimal transmission coefficient and energy-loss coefficient. Without a collar barrier, the single net and double net cage can only provide average wave transmission coefficients of 0.9 and 0.8, respectively. This study finds that the transmission coefficient could be reduced below 0.4 by having a single collar barrier withh = 4m ande= 0.25. On the other hand, the transmission coefficient could be further reduced below 0.3 by a double collar barrier with the sameh and e.In addition, the double collar barrier gives lower energy-loss coefficient and better proofing against fish escape, biosecurity and predator intrusion than the single collar barrier. A double collar barrier design with porosity combination ofe1=0.25,e2=0.5 is recommended for the COSPAR fish cage as it yields competitive wave scattering performances and saves collar material by 25% when compared with the best performing porosity combination ofe1= e2=0.25.

中文翻译：

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抗波浪作用、碎片和捕食者的近海浮式鱼笼多孔围栏的设计开发

摘要 本文提出了一种新型浮动式开放式网箱与浮动式翼梁风力发电机组（简称COSPAR鱼笼）的多孔围栏设计概念。COSPAR鱼笼呈八角形，每边长30m。具有一系列圆角矩形切口的项圈屏障安装在笼子的顶部，以减弱笼子内的波传输并保护鱼类免受外部捕食者和碎片的侵害。研究了与单网和双网笼相对应的单圈和双圈护栏设计。基于线性势波理论和本征函数展开方法，通过数值分析确定了障碍物的波传输、反射和能量损失系数。研究了各种水下高度（2m ≤ h ≤ 8m）和孔隙率（0.25≤ e≤ 0.75）的领口屏障，以获得最小传输系数和能量损失系数的屏障设计。在没有领口屏障的情况下，单网和双网笼分别只能提供0.9和0.8的平均透波系数。该研究发现，通过使用 h = 4m 和 e = 0.25 的单项圈屏障，可以将传输系数降低到 0.4 以下。另一方面，通过具有相同h和e的双领屏障可以将传输系数进一步降低到0.3以下。此外，双领屏障具有更低的能量损失系数和更好的防止鱼类逃逸、生物安全和捕食者入侵的能力。单项圈屏障。