Study on Edge Shape of Very Large Floating Structures to Reduce Motion

In recent research, it has cleared that the motions of pontoon type very large floating structures (VLFS) are dominated by the dissipation wave that is induced by the floating structure and the fluid interaction. Incident wave excites the weather side of the structure, and then the deformation is propagated over all the structure. The deformation wave propagation to the main part of VLFS is not desirable, because the deformation requires the large area of high strength of the structures and the motion might affects the function of VLFS. In this study, the edge shape of VLFS that restrains the propagation of the deformation wave has been investigated. To evaluate the effect of the improved edge form, a program to calculate the response of VLFS that has arbitrary horizontal outline has been developed. Using the program, it has been confirmed that the notched edge reduces the deformation of the inner area of VLFS. In order to reduce the motion effectively, a relation between the edge form and the incident wavelength was found.