Validation of CFD for run-up and wave impact on a semi submersible

To assess the integrity and safety of structures offshore, prediction of run-up, green water, and impact loads needs to be made during the structure’s design. At present, most of the industry relies on detailed model testing for predicting these typically highly non-linear phenomena. Nowadays however, CFD simulations are also starting to play a role in studying these events. To obtain confidence in the accuracy of CFD simulations, a proper validation of such CFD tools is essential.
In this paper the in-house developed CFD tool ReFRESCO using an unstructured gridding approach and implicit free-surface reconstruction will be validated in the field of wave impacts. As test case, a steep regular wave hitting a semi submersible is considered, resulting in flow phenomena like wave run-up, horizontal wave impacts and deck impacts. The simulation uses a compact computational domain with wave absorbing boundary conditions and local grid refinement to reduce CPU time. Results will be validated against experiments carried out by MARIN and data obtained with the benchmark CFD tool ComFLOW, dedicated and validated to the area of wave impacts.