A Comparison of Different Numerical Methods to Simulate Forced Roll Oscillations of Floating Structures in Grid-Based Schemes

Abstract

Abstract To accurately describe the motion of floating structures in waves using low-fidelity methods (Boundary Element Method, analytic methods), roll damping has to be determined with higher fidelity due to the influence of viscous effects. In these higher-fidelity estimations, either existing models like Ikeda’s model, which was validated using model test results, or Computational Fluid Dynamics simulations are frequently used. Forced roll tests are the main method to estimate the hydrodynamic properties (damping & added mass). In this study, three different numerical approaches to simulate structures in roll motions in grid based Finite Volume Method schemes are compared regarding their efficiency and numerical accuracy. The results of this study show a good agreement between all three methods. While mesh morphing and Arbitrary Mesh Interface show similar results, the runtime of the Arbitrary Mesh Interface is increased by factor three. The most computationally challenging method is the overset method, which has its benefits in more complex motion environments and need further improvement to be a feasible alternative to the established methods mesh morphing and Arbitrary Mesh Interface.