A toolbox for fluid-structure interaction of slender bodies

Hydrodynamic loading of solid bodies like ships or breakwaters can be simulated well using geometry resolving computational fluid dynamics methods, where the body shape is resolved in the mesh describing the domain. Slender bodies, like spars, multiple tidal tur-bine blades or lattice structures would often require pro-hibitively high cell counts, since the geometrical features to be resolve are much smaller than the overall domain. However, such bodies are usually made up of generic cross sections like round, square or standardised technical profiles like the famous NACA 4/5 digit series for which good para metrisations of reaction forces to incoming flow exist. Actuator line methods thus apply inflow dependent reaction forces to the fluid domain, allowing the compu-tationally efficient simulation of slender bodies and have been used extensively, for example for wake assess mentsor tidal turbine array simulations. Slender bodies are also standard building blocks of structural simulations using the finite element method. Combining actuator line theory with a finite element beam model allows to efficiently simulate flexible structures, like tidal turbine blades or nettings used in fish farms. This paper presents an imple-mentation of such a coupled model in Open FOAM. The underlying numerical method is detailed and first example application and validation cases are provided