A4 - Modeling and simulation of fluid-structure-soil interaction for offshore megastructures.

The reliable prediction of scour development is an essential element of foundation structure design and will play an important role for the expansion of offshore wind energy. In general, scour refers to localized removal of soil material around structures installed in fluvial and marine environments. Scour can lead to significant stability problems and eventually structural failure. Although extensive research has been carried out on this topic over the past decades, the occurrence, drivers and effects of scour have been investigated mostly for slender structures such as small-diameter monopiles. On the other hand, scour around larger and more complex foundation structures such as tripods, jackets or large-diameter monopiles was studied less thoroughly so far, although the necessary expansion of offshore wind into deeper waters relies on these very structures.

As part of the collaborative research center “CRC 1463 Offshore Megastructures”, the main objective of SP A04 are:

• Prediction of scour formation for offshore megastructures and its estimation under varying Metocean conditions by laboratory experiments and numerical means.
• Investigation on transferability of model parameters and prediction approaches between adifferent length scales (from small to large) and complexity of structures (from monopiles to tripods or jacket type foundation).
• Modeling for better design of scour protection system

A numerical model for scour development will be calibrated and validated using the experiments to be carried out along with SP A03 on top of the available field data and numerical tests in the literature. Experiments with different length scales, different flow conditions (wave & current) and different structural complexity such as Tripod or jacket type foundations will be carried out.

The innovation of SP A04 lies in a systematical investigation of the capabilities and limitations of numerical models to predict scour initialization. In particular, the transferability of model parameters will be investigated. Furthermore, the projections of the development of scour due to changing hydrodynamic impacts over the life cycle of an offshore structure shall be elaborated. On the other hand, SP A04 provides robust studies of scenarios for necessity, suitability and durability as well as recommendations for the practical design of scour protection measures for marine engineering structures. It interacts strongly with SP A03, A06 and B04, aiming to elaborate reliable predictions for the initialization and temporal evolution of scour in the near-field of offshore megastructures.