Sensitivity of the least stable modes to passive control for a flow around an elastically mounted circular cylinder

Abstract

We present a method to calculate the sensitivity of the two least stable eigenvalues with respect to an external forcing added in a fluid-structure interaction system (FSIS). Sensitivity computations are performed by setting the external forcing proportional to flow velocity applied to a local point in the domain. We find that the sensitivity fields of an FSIS can be very different from its fixed structure counterpart. For an elastic structure the fields vary according to the reduced velocity. These sensitivity fields allow for passive control strategies, as confirmed by nonlinear simulations which result in vortex-induced vibration attenuation or mitigation, depending on the case.