The Use of a Volume Of Fluid (VOF) Method Coupled to a Time Domain Motion Simulation to Calculate the Motions of a Subsea Structure Lifted Through The Splash Zone

Existing simulation methods are not able to determine in detail the wave loads on and the motions of a complex subsea structure when it is passing through the splash zone. To determine these loads and motions, model tests are necessary. Otherwise only simplified formulations or empirical relations for added mass and damping can be used. The improved Volume Of Fluid (iVOF) method presented in this paper is capable of predicting the behaviour of a subsea structure in the splash zone. The simulated flow around and through the structure looks very realistic and shows a strong resemblance with observations from model tests. The quantitative comparison of the load variations in the hoist wire of the subsea structure shows that the total load levels and dynamics of the subsea structure are well predicted. This good comparison shows the potential of the improved Volume Of Fluid (iVOF) method for the simulation of the behaviour of subsea structures in the splash zone. However, significant further development is needed before long simulations in irregular waves can be carried out. At the moment, the method is limited to short runs (regular waves) because of the long simulation times required at the moment.