Coupled FSI simulations of the interaction of a flexible hydrofoil with large scale unsteady flows

Fluid-structure interaction (FSI) effects must be considered when flexible structures are subjected to unsteady flows. Large-scale unsteady flows can excite structural vibrations significantly and cause the fluid flow to be altered by the large amplitude vibrations. In this work, an in-house finite-element structural code FEANL is tightly coupled with the open-source computational-fluid dynamics (CFD) library package OpenFOAM to simulate the interaction of a backward-skewed, flexible hydrofoil with vortical flow structures shed from a large upstream rigid cylinder in the Penn State-ARL 12″ water tunnel. To simulate the turbulent flow at a moderate computational cost, hybrid LES-RANS approaches, i.e. Delayed-Detached-Eddy-Simulation (DDES) and k-03 SST-SAS, are used. The hybrid approaches have been widely employed to simulate massively-separated flows at moderately high Reynolds numbers. Both of the turbulence models are used for a coarse mesh CFD-only case (no FSI effects by assuming a rigid structure) to test their capabilities, and the results of the two models are compared. DDES is chosen to simulate a fine mesh CFD-only case to conduct a mesh convergence study, and it is then used for final FSI simulations. The purpose of this work is focused on obtaining computational results; detailed comparisons against experimental data will be made in future work.