State-of-the-art and Development Needs of Simulation Codes for Offshore Wind Turbines

Offshore wind turbines have been installed in increasing water depths over the last years. Support structures with monopile or gravity based foundation could successfully be used for all realized offshore-projects, but the trend of increasing water depths reached a level that makes application of those relatively simple types of support structures inappropriate. New concepts like tripods or lattice types are developed covering all parts of the support structure. A number of sophisticated codes exists that can simulate offshore wind turbines in an integrated and/or superimposed manner, but most of them are currently limited to tubular towers with monopile or gravity based foundations. Therefore those codes are extended to meet the requirements of modelling more complex support structures such as tripods, jackets and even floating structures. This paper gives an overview on certain aspects related to offshore wind turbine modelling focusing on the support structure and the offshore environment. In this context the current status of a number of simulation codes is presented. Needs and current development related to support structure concepts, system and sub-system models will be discussed taking into account the requirements within the design process as well as limitations of some models. Furthermore, some recent and future verification activities are discussed.