Modeling of vortex-induced vibrations of an elongated rectangular cylinder through wake-oscillator models

The problem of modelling VIV of elongated bluff bodies and bridge decks was dealt with. Modified versions of both the Skop-Griffin model and the harmonic model were proposed and validated against wind tunnel tests. The capability of predicting VIV by a modified version of the Tamura-Matsui model was also checked. The modified Skop-Griffin model was able to predict both the Griffin plot and the response curves. Interestingly, despite its simple formulation, the harmonic model showed suitable results in predicting the Griffin plot. This strongly suggests the key role played by the aerodynamic damping introduced in the modified versions of both models according to the quasi-steady theory, in spite of the expected poor accuracy of the latter at low reduced flow speed. The Tamura-Matsui model, which already incorporates the quasi-steady force contribution, was found to predict correctly the peak amplitude of the response at different Scruton numbers, as well as the width of the lock-in range. Finally, all the models tested were not able to predict the onset of the VIV excitation significantly before the resonance wind speed as observed in the experiments.