Development of accurate fluid-structure interaction models for aerospace problems

The research program deals with fluid-structure interaction (FSI), a challenging field of engineering, with a practical application on aerospace problems such as the flutter, an instability problem due to aeroelastic excitations. The research goal is to find a suitable way to deal with flutter in such a way the two macro fields, fluid and structure, are modelled with mid to high-level accuracy. Moreover, the creation of an interface could be useful to study other problems, such as the cabin comfort for an aircraft. To do that, the research activity is firstly split in two to study in depth the structural and the fluid problem, then they are merged together through the interface analysis: the main problem is that each field has an own scale and the union of both requests a suitable modelling and analysis. After a preliminary study on the state of the art of fluid-structure interaction in literature, which forms the pillar of the research project, the structural field is analysed first. The study of the structure system is carried out on the Carrera Unified Formulation (CUF), which allows a reduced degrees of freedom model with the same accuracy of the classical Finite Element Method (FEM). Analysis on possible adaptive mesh methods is needed in order to match the proper scale at interface with fluid dynamics system. This work could be a milestone for future investigation in problems that need a mesh refinement, beyond the aeroelastic field. Then, the fluid system is studied and analysed through the Navier-Stokes equations. In particular, a Dual Time Stepping model for non-stationary Favre Average Navier-Stokes is used. More in general, considering different order of magnitude for the Reynold’s number, three different analysis could be done: Reynolds Average Navier-Stokes (RANS) for only large-scale eddies resolved and other components modelled, Large Eddy Simulation (LES) which adds the resolution of the flux of energy with respect to the previous simulation and Direct Numerical Simulation (DNS) which resolves also the dissipating eddies, so representing the best performing simulation but with very high computational cost. Finally, a complete simulation of fluid-structure interaction is performed to find the flutter velocity and study the induced vibrations from turbulent boundary layer to the aircraft cabin and/or to the rocket nose.