Modelling of wake-induced vibrations of tandem cylinders with a nonlinear wake-deficit oscillator

For a pair of elastically mounted circular cylinders in tandem configuration, the downstream cylinder may experience wake-induced vibration (WIV) due to hydrodynamic excitation associated with wake behind upstream cylinder. In addition WIV, also be simultaneously subject vortex-induced (VIV) vortex shedding its own wake. This nonlinear coupled wake-vortex interaction can result sustained large-amplitude response depending on spacing. this study, new wake-deficit oscillator model for predicting combined WIV-VIV responses cross-flow direction is presented. While stationary or oscillating placed uniform steady flow, non-uniform unsteady flow space–time varying velocity being modified by deficit shielding effect. The total force modelled as combination transverse and lift drag forces. approximated using theory based linearised boundary layer equation. van der Pol which incorporates velocity, relative flow-cylinder velocities dynamically staggered positions between two interfering cylinders. These empirical equations are nonlinearly coupled, simulating leading fluid–structure parameters. By focusing interference regime, profiles forces calibrated validated, introducing coefficients functions. oscillation frequencies predicted compared relevant experimental data accounting important effects spacing ratio, reduced Reynolds number subcritical regime. stiffness characterisation presented, providing an analytical formulation related dynamic profile. Several key features WIV amplitudes highlighted discussed oscillator. present concept further improved account in-line arbitrarily arrangement well application multiple long flexible multi modal responses.