Vibration and radiation from underwater structure in shallow water

Abstract

Prediction of vibration and radiation from large underwater structures is one of the most important research contents in engineering. The cylindrical shell structure is most common structure in engineering, and it is the main component of submarine at the same time. Shells with structural similarity have similar properties due to the similarity principle. Free vibration of the simple cylindrical shell in shallow waters with proper structure mesh and flow field gird is firstly carried out with the usage of finite element method (FEM). The comparison between the FEM result, analytical solution and experimental results gets a satisfactory agreement, indicating the accuracy of FEM approach when used in the fluid-structure interaction problem. A stiffened cylindrical shell structure in shallow waters, taking consideration of the surface and bottom of the waters, is also studied. The natural frequency data and radiation results provide assessment of the influences of water depth, free surface and rigid boundary occurring in the fluid-structure interaction process. The acoustic response in infinite water domain is calculated in parallel. The result shows that the impact of surface, bottom and depth in water on the structure vibration response and the acoustic radiation cannot be ignored, which could provide experimental and numerical introduction in underwater vibration and radiation prediction or measurement.