Analysis of a Moored and Articulated Multibody Offshore System in Steep Waves

Abstract

Wave-induced motions of and loads on a moored and articulated multibody offshore structure are numerically analyzed, where a coupled mooring-joint-viscous flow solver was used to account for mooring dynamics, joint restrictions, nonlinear rigid body motions, and viscous flow effects. The considered concepts consisted of two MFSs connected by two types of connections, namely a rigid joint and a flexible joint, and positioned by four symmetrical catenary mooring lines. The analyzed responses comprised multibody motions as well as associated forces acting in the hinged joints and the mooring lines. Results indicated that surge motions of the articulated bodies were almost identical to each other, whereas the effects of the joint on heave motions were not pronounced. However, highly dynamic pitch motions between two hinged MFSs were observed. Apart from motion responses, forces acting on the hinged joint and the mooring lines were estimated. The coupled mooring-joint-viscous flow solver demonstrated its capability to predict wave-induced motions of and loads on a moored multibody offshore structure articulated by various types of joints.