Mass ratio definition of vortex-induced vibration systems with added mass consideration

This study proposes an alternative mass ratio definition for vortex-induced vibration (VIV) systems. The proposed definition, henceforth known as 'total mass ratio', differs from the conventionally used mass ratio definition (i.e. the ratio of the mass of the oscillating body to the mass of the displaced fluid) in that the added mass of the fluid is taken into account. Two-dimensional numerical simulations are conducted to compare the effect of mass ratio on the VIV response of two cylinders with different cross sections, namely, a fully-filled solid cylinder and a hollow cylinder with fluid-filled cavities; both are designed to generate identical flow characteristics. When plotted against the conventional mass ratio, VIV response amplitudes of the fully-filled and hollow cylinders are different despite the similarity in flow characteristics. Conversely, the trends of VIV response amplitude against total mass ratio for both cylinders overlap almost perfectly. Results therefore suggest that the total mass ratio definition yields a more complete representation of the mass property of the VIV system, especially when comparing cylinders of different cross-sectional geometries.