Analysis of the Dynamics of a Floating body with Thin Skirts by Using the Dual Boundary Element Method

Abstract

In this study, a numerical simulation of the dynamic behavior of a novel floating structure with rigid skirts was conducted using the dual boundary element method. The thickness of the skirts mounted beneath the structure was negligible. A theoretical analysis was derived from linear wave theory, and a nonlinear drag term was added in the motion equation of the floating structure for improving the solution. This study investigated the effects of double vertical skirts on a free floating structure and verified the validity of the analysis by comparing the result with those of Gesraha (2006). The results showed that adding double vertical skirts increases the overall mass of the structure, thus enabling the floating structure to resist wave forces for longer periods. The main purpose of this paper was to investigate the influences of the angles of the skirt attachment and the nonlinear drag term, on the moored floating structure. This study focused on the changes in the structure's motion in each mode, reflection and transmission coefficients, energy loss induced by the nonlinear drag term, and various angles of skirt attachment. The analytical results agreed with the experimental data. Involving a nonlinear drag term in the analysis yielded superior results, particularly when the structure approached the natural period in the three modes of oscillation.