Synchronization of Vortex Dynamics and Cavitation in Flexible Cantilevered Hydrofoils

We numerically study the combined vortex and cavity synchronization/lock-in in a flexible cantilevered hydrofoil at a high Reynolds number. The fluid-structure interaction of this system is of interest in characterizing the cavitation-induced vibrations of marine propellers. For an elastically mounted hydrofoil, cavitating conditions result in large vibrations at low angles of attack, with distinct lock-in and post-lock-in regimes, stemming from the interaction of vortex and cavity dynamics. However, in the case of an elastic structure, flexural and torsional modes can alter the nature of synchronization. In the current work, we aim to explore the mechanism associated with the vortex-cavity excitation of a flexible hydrofoil by answering three questions: (a) What are the regimes of lock-in which can be delineated owing to the presence of a multi-modal nonlinear structure? (b) What are the response characteristics of the flexural and torsional modes? and (c) How does the presence of cavitation alter the vortex dynamics and consequently hydrodynamic loads acting on the structure in contrast to non-cavitating conditions?