| Summary: | 碩士 === 國立中山大學 === 海洋環境及工程學系 === 87 === Abstract
In this thesis, analytical solutions have been developed to quantify the flow field for surge motion of a deformable tension leg platform induced by a monochromatic linear wave train. Also an experiment study was used to check the analytical solutions.
It is assumed that the fluid is incompressible, inviscid and the flow is irrational. The material properties are considering homogenous and linear elastic, fixed at bottom by the tension leg. It is further assumed that the platform deformation and surge motion is small, and therefore with linear boundary conditions. Then, the corresponding boundary value problem is incorporated into scattering and radiation problems. The boundary value problems are then solved by the method of separation of variables and combined to resolve all unknowns.
The convergence of the series solutions is tested by increasing the number of wave modes and the existence of the solution is confirmed. The flow fields quantifying the interaction of a linear incident wave train and the floating platform have been studied by varying wave conditions and structure properties, such as width, draft, mass and material young''s modulus. Results show that most parts of longer incident waves transmit through the floating structure. However, when incident waves are short, the structure reflects most of the incident wave. Comparing the analytical solution with that form experiments, the results show reasonable consistence in trend. It is noted that the difference between analytical and experimental results may be due to the energy dissipation and the back reflection in the wave tank, especially for long waves which may have 30% reflection coefficient. Besides, it is found that the resonance frequency of the platform surge motion varies with the system stiffness and add mass.
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