Numerical investigations of the fluid-structure interaction of a NACA0012 airfoil based on large-eddy simulations

The purpose of this work is to expand the work of Streher (2017) in order to investigate the aeroelastic instabilities generated by the flow around a moving NACA0012 airfoil. The profile has a chord length of $c=0.1 m and is exposed to a flow at a Reynolds number of Re=30,000. The airfoil has only two degrees of freedom: Translation in relation to the vertical direction and a rotation around the span-wise axis. A partitioned approach based on two separate solvers and a fluid-structure interaction (FSI) coupling scheme is applied. The in-house CFD solver FASTEST-3D computes the fluid sub-problem according to the wall-resolved large-eddy simulation (LES) combined with the Smagorinsky model (1963). The structural sub-problem is solved by a rigid movement solver implemented by Viets (2013), which is based on the equations of motion for rigid bodies. The FSI coupling exchanges information between both solvers based on loose or strong coupling algorithms. A thorough analysis of the problem is primarily performed in order to acquire a computational setup that provides the best compromise between accuracy and CPU-time requirements. Three system configurations are then tested and thoroughly investigated: One leads to an oscillatory behavior of the airfoil characterized by limited small amplitudes. The other is characterized by the presence of the torsional divergence aeroelastic instability. Finally, a configuration aimed at the flutter phenomenon is established. However, not enough data are currently available and therefore this dynamic aeroelastic instability can not be thoroughly investigated in the present work. In the near future, this study will serve as a base for the flutter experiments and computations performed at the Department of Fluid Mechanics located of the Helmut-Schmidt-University.