On the dragged surge vibration of twin TLP systems with multi-interactions of wave and structures

In this study, the wave-induced surge motion of a twin platform of tension leg structural system was investigated. A set of equations along with boundary conditions was derived, and solutions were obtained analytically. In the analysis the coupling problem of a two-dimensional tension leg twin platform interacting with a monochromatic linear wave train in an inviscid and incompressible fluid is considered. The problem was considered as a combination of the scattering and radiation problem. These two boundary-value problems were first solved independently and then combined together to resolve for all unknowns. The analysis was focused on the wave-induced surge motion of the twin platform and the reflection coefficient when the multi-interactions among waves, platform structure and the tension legs were taken into account. From the analytical results, it was found that ignoring the interaction effect between the tether and waves for a twin platform system, it tends to overestimate the wave-induced response in general. It was also realized that the behavior of the tension-leg twin platform was significantly influenced by dimensional factors of the platform system such as the dimension of each platform and the spacing between two platforms.