Efficient Methods for Hydroelastic Analysis of Very Large Floating Structures

The linear hydroelastic response of a very large floating structure (VLFS) consisting of multiple modules is studied theoretically, following a review of the past work on hydroelasticity in fluid-structure interaction. The 3-dimensional Green function method and Morison's equation approach are used to determine the fluid loading in conjunction with two different hydroelastic models. The first method uses a rigid module, flexible connector model in which the hydrodynamic interaction between rigid modules is taken into account. The double composite source distribution method, which is a numerically efficient implementation of the Green function method that exploits double symmetry of the structure in the longitudinal and lateral directions, is used to reduce computations. In the second method, fully elastic modules are considered. In this approach, the fluid loading is obtained by Morison's equation, and the structure is modeled by frame finite elements. The predictions for the rigid-body motions and structural deformations, as well as module-connector loads, obtained by the two different methods are compared. The proposed methods of hydroelasticity have been used to predict the response of a 16-module VLFS, 100 m by 1600 m. Both methods are sufficiently efficient to allow the analysis of even larger VLFS.