Numerical study on the flow-induced vibrations of a flexibly-mounted cavity at the rear of a bluff body

Resumen

We carry out a computational study on the flow-induced vibrations (FIV) of a rigid cavity, flexibly mounted at the rear of a D-shaped body of height H, subject to a cross-stream of velocity u∞. Simulations are performed for laminar Reynolds numbers to characterize the interaction between wake and parallel rotary plates, connected to the rear edges of the body using torsional hinges. The FIV amplitude response and the effect on force coefficients are investigated for several values of hinge's torsional stiffness k, which provide with different natural oscillation frequencies fn and reduced velocities U*=u∞/fnH. A large FIV response is found for U* >2, where plates oscillate in phase at the shedding frequency. Such response increases the mean drag and fluctuating lift, although reductions are found U* <2, where a weaker FIV response is characterized by oscillation of plates in counter-phase. Finally, to validate the results, we develop a multibody model that allows to retrieve the local aerodynamic forces and torque acting on the plates, using the motion obtained from simulations as input. A final analysis is performed in terms of torque's components and phase between wake forcing and plates' response.This work was supported by the Spanish MINECO under Project DPI2017-89746-R .