The safety of the offshore net cage and the survival environment of cultured fish are closely related to the net system. Since the damage caused by predators or biological fouling significantly threatens the longevity of the net system, this paper aims to understand the hydrodynamic characteristics of the biological fouling net in the open ocean. First, the equivalent model of the biofouling net is proposed, and the drag force coefficient and flow field variations are studied using large-eddy simulation (LES). The results highlight that the cross-sections contacted with fluid lead to a smaller drag force coefficient for 2 × 2 cruciform circular cylinder. Then, the fitted formula of the drag force coefficient under different biological fouling levels is established. Moreover, the length of recirculation flow is irrelevant with the number of net twines, but it is greatly affected by the biological fouling level. Wake vortices behind the fouling net is more disordered as the biological fouling level increases. Finally, the influence between the net aperture and the net twines on the wake are also accessed in this paper.

近海网箱的安全和养殖鱼类的生存环境都与网制密切相关。由于捕食者或生物污垢造成的损害严重威胁着网系统的寿命，本文旨在了解公海生物污垢网的水动力特性。首先，提出了生物污垢网的等效模型，并使用大涡模拟（LES）研究了阻力系数和流场变化。结果突出显示，与流体接触的横截面导致 2 × 2 十字形圆柱体的阻力系数较小。然后，建立了不同生物污垢水平下阻力系数的拟合公式。而且，再循环流的长度与网缠绕的数量无关，但受生物污垢水平的影响很大。随着生物污垢水平的增加，污垢网后面的尾流涡流更加无序。最后，本文还访问了净孔径和网缠绕对尾流的影响。