波浪作用下双层网底鲆鲽网箱水动力特性的数值模拟

Numerical Simulation of the Hydrodynamic Characteristics of Double-Bottom Cage for Flounder Fish Under Waves

中文关键词: 双层网底  水动力  有限元方法  鲆鲽网箱

英文关键词: Double-bottom  Hydrodynamic characteristics  Finite element method  Cages for flounder fish

中文摘要:

      根据有限单元法建立了波浪作用下双层网底网箱的受力运动模型，通过数值计算求解双层网底的位移与倾角。先将上层网底与下层网底的计算值进行比较，然后，将双层网底网箱中下层网底与单层网底网箱开展对比分析。计算结果显示，在波浪周期内，双层网底网箱的2层网底能保持相对平行的状态。2层网底的位移与最大倾角随着波高与周期的增大而增加，并且2层网底的倾斜方向一致。在相同波浪条件作用下，下层网底的水平位移大于上层网底，二者垂直位移差异较小，下层网底最大倾角值大于上层网底。研究发现，当波高为15 cm、周期为1.4 s时，双层网底网箱的2层网底的倾角相差最大，但并未发生接触碰撞，网底可以保持相对稳定。此外，双层网底网箱的下层网底的最大位移值小于单层网底网箱，最大倾角值大于单层网底网箱。研究表明，当波浪一定时，双层网底网箱的最大锚绳力均大于单层网底网箱。

英文摘要:

      The double-bottom cages for flounder fish tend to move and deform under waves. Therefore, it is necessary to carry out hydrodynamic analysis for the stabilization of flounder fish cages. Herein, a numerical model of deformation of double-bottom cages under waves was established based on the finite element method, and then maximum displacement and the pitch of the double-bottom were calculated. First, results of the upper bottom were compared with that of the lower bottom. Afterwards, the results of the lower bottom of double-bottom cage were compared with that of the single-bottom cage. The simulation results showed that the two bottoms of double-bottom cages were able to stay relatively parallel during wave periods. The maximum displacement and pitch of the two bottoms increased along with not only wave height but also wave period. In addition, the inclined direction of the two bottoms was the same. Under the same wave conditions, the horizontal of displacement and the maximum pitch of lower bottom were larger than those of the upper bottom, but their vertical displacements were not much different. It was found that the difference in pitch between upper and lower bottoms was the largest when the wave height was 15 cm and the wave period was 1.4 s. However, the upper and lower bottoms of the cage did not collide with each other, and the two bottoms of the cage could remain relatively stable. Moreover, under the same wave conditions, the displacement of the lower bottom of the double-bottom cage was less than that of the single-bottom cage, but the pitch of the lower bottom of the double-bottom cage was larger than that of the single-bottom cage. Additionally, the maximum mooring-line force of double-bottom cages for flounder fish was larger than that of single-bottom cages. Furthermore, the study on the hydrodynamic characteristics of double-bottom cages for flounder fish under the combined action of wave and flow should be carried out in the future.