Hydrodynamic Analysis of Elastic Floating Collars in Random Waves

• Published in: China ocean engineering Vol. 29; no. 3; pp. 341 - 356
• Main Author: 白晓东 赵云鹏 董国海 李玉成
• Format: Journal Article
• Language: English
• Published: Nanjing Chinese Ocean Engineering Society 01.06.2015; State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,Dalian 116024,China
• Subjects: Coastal Sciences; Engineering; Fluid- and Aerodynamics; Marine & Freshwater Sciences; Numerical and Computational Physics; Oceanography; Offshore Engineering; Simulation; 弹性变形; 弹性响应; 控制方程; 水动力分析; 浮箍; 物理模型试验; 随机波浪; 面内变形; net effect; random waves; floating collars; in-plane and out-of-plane deformation; hydrodynamic characteristics
• ISSN: 0890-5487; 2191-8945
• DOI: 10.1007/s13344-015-0024-0

As the main load-bearing component of fish cages, the floating collar supports the whole cage and undergoes large deformations. In this paper, a mathematical method is developed to study the motions and elastic deformations of elastic floating collars in random waves. The irregular wave is simulated by the random phase method and the statistical approach and Fourier transfer are applied to analyze the elastic response in both time and frequency domains. The governing equations of motions are established by Newton＇s second law, and the governing equations of deformations are obtained based on curved beam theory and modal superposition method. In order to validate the numerical model of the floating collar attacked by random waves, a series of physical model tests are conducted. Good relationship between numerical simulation and experimental observations is obtained. The numerical results indicate that the transfer function of out-of-plane and in-plane deformations increase with the increasing of wave frequency. In the frequency range between 0.6 Hz and 1.1 Hz, a linear relationship exists between the wave elevations and the deformations. The average phase difference between the wave elevation and out-of-plane deformation is 60° with waves leading and the phase between the wave elevation and in-plane deformation is 10° with waves lagging. In addition, the effect of fish net on the elastic response is analyzed. The results suggest that the deformation of the floating collar with fish net is a little larger than that without net.