Coupled Dynamic Analysis of a Mini TLP: Comparison With Measurements

A numerical code (COUPLE) was recently developed for computing 6 Degree-Of-Freedom (DOF) motions of a moored floating structure dynamically interacting with its mooring/riser/tendon system. The computation of hydrodynamic forces on the moored structure can be conducted based on a diffraction wave theory model, e.g. WAMIT, and/or the Morison Equation based upon a slender body assumption. Wave kinematics up to the free surface, used in the Morison Equation, is computed using nonlinear deterministic Hybrid Wave Models, and is accurate up to second order in wave steepness. Experimental data from the model tests of a mini TLP was used as the basis for investigation of the numerical computation. Using COUPLE and its alternatives, coupled as well as quasi-static analyses were conducted for the mini TLP model that incorporates four risers and four tendons. Two different methods for computing hydrodynamic loads, namely, WAMIT and Morison Equation, were used, respectively. Through the comparison between the numerical results and the corresponding measurements, dynamic interactions between the riser/tendon system and the hull were examined. Findings made in this study, though based upon a mini TLP may have valuable applications to the design and simulation of a wide range of compliant deep-water structures.Copyright © 2002 by ASME