Time-Domain Simulation of Subsea Equipments Installation Using Hydrodynamic Derivatives

Abstract

The installation of a subsea equipment such as manifold needs careful planning and coordination. Studies on the behavior of the dynamic responses are crucial to guarantee safety. Some important factors in these operations include the current profile, waves characteristics, winches motions at topside, and the elastic behavior of the cable (due to resonance effects). Currently, most of the available commercial codes use simplified models for the hydrodynamic forces of submerged equipment. However, for cases with complex geometries and strong interactions with the environmental loads, those models fail to represent correctly the dynamics. In this paper we present an initial method and a hydrodynamic model to include terms that allow the modelling of complex behavior of submerged complex geometries by using hydrodynamic derivatives extracted from model tests. To verify the procedure, tests were performed both at a flume tank and at a towing tank. The model was implemented in a commercial code by using a Simplified Buoy model, to which a python procedure that calculated the hydrodynamic forces was attached. The study was divided into two phases: the first one consisted of the verification of the effectiveness of the external routine. This was done for a manifold in 1DOF and then in 6 DOF. In the second phase, the dynamic maneuvering model using Hydrodynamic Derivatives was implemented as an external routine and, using the output from dynamic excitation experiments at small scale with a manifold, kinematical behavior results were compared. Results showed good adherence, although some further investigations are still needed.