ABSTRACT
This paper presents numerical modelling results of the interaction between a group of steep waves and a fixed vertical cylinder performed with a one-way coupled hybrid model. A set of experimental data is used to benchmark the accuracy of the modelling results. The wavemaker signal generated in the physical experiments is used to reproduce the incident wave conditions without a priori knowledge of the rest of the dataset. A Lagrangian numerical wave flume propagates the wave group, producing the non-linear free surface elevation and wave kinematics with high accuracy in the vicinity of the cylindrical structure. This set of data is used as the input to the olaFlow CFD model, which calculates the wave-structure interaction on a small computational domain. One-way coupling approaches based on boundary conditions and relaxation zones are tested and compared in terms of the recorded free surface elevation and pressures at the structure. Results present an adequate degree of accordance and turbulence effects are found to be negligible in the simulations.
Wave and structure interaction (WSI) is a field in which numerical modelling is nowadays being applied consistently and with increasing popularity. The challenges derived from modelling the impact of waves and structures are numerous. Marine and offshore structures are usually located in areas subjected to extremely harsh conditions, in which often waves present three-dimensional and highly-nonlinear processes such as wave breaking and wave impacts may result in impulsive loading.
Under such conditions the relevance of numerical modelling, and especially computational fluid dynamics (CFD), derives from the low number of underlying assumptions that the Navier-Stokes equations involve, from their inherent nonlinearity and from their capability to include turbulence dissipation effects via Reynolds-Averaged Navier- Stokes (RANS) or Large Eddy Simulation (LES) turbulence models. Furthermore, despite its advantage and flexibility, numerical modelling results alone have a limited practical credibility if they are not accompanied by a reasonable validation against experimental measurements, which is why physical and numerical modelling should be deemed as complementary approaches.
