Nonlinear wave response analysis of very large floating structures subjected to nonlinear random waves in variable water depth

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In this research, nonlinear wave response analysis of very large floating structures subjected to nonlinear random waves in variable water depth has been investigated. The main objective is to develop a computer simulation program for accurate and efficient evaluation of wave response of a Very Large Floating Structure(VLFS) located in variable depth sea subjected to nonlinear waves.In the fiscal year of 2002, wave-field analysis program was considered using plane 2-d model. The developed program can express the wave-propagation onto the inclined beach, and the applicability to the strong non-linear wave has been confirmed. Also, the wave diffraction analysis program around an arbitrary shape floating body in the frequency domain has been developed ; where the bichromatic waves can be considered.In the fiscal year of 2003, the wave diffraction analysis program subjected to bichromatic and bidirectional waves has been developed, where 2^<nd> order nonlinear waves can be considered. Slow … More drift oscillation of a large pontoon including the effect of elastic deformation has been analyzed by the developed program, and it has been clarified that the conventional approximate method using constant drift force would fail, unless the second order diffraction force is considered rigorously. Also, the acceleration method for application to a very large floating structure in the computational point of view has been examined, and the accelerated program has been developed.In the fiscal year of 2004, the wave diffraction analysis program subjected to bichromatic and bidirectional waves has been completed and extended to cover the analysis of non-linear wave run-up analysis around the floating structure. Also, in the acceleration algorithm using the multipole expansions, the convergence characteristics for iterative solver is the key point for computation time reduction ; thus, the research for modifying the iterative solver has been made, and finally, the reduction of computation time up-to 1/5 -1/10 has been obtained. Less