Illuminating the complex role of the added mass during vortex induced vibration

The role of the added mass coefficient in vortex induced vibration (VIV) of the bluff body is complex and elusive. It is certain that decoding the relationship between the added mass and the vibration pattern will benefit the prediction and prevention of VIV. We present a study on VIV of a long flexible cylinder and forced vibration of a rigid cylinder, in a combination of experimental optical measurements and high-fidelity numerical simulation. We focus on uniform flow over a uniform cylinder at a fixed Reynolds number, Re-d = 900, but systematically varied the motion amplitude in the in-line (A(x)/d) and cross-flow direction (A(y)/d), as well as the phase angle (theta) between the motions. We show that theta is an element of 2 [pi/2, 3 pi/2] is associated with negative added mass coefficients in the cross-flow direction (Cmy < 0), and there is a strong correlation between the vortex shedding mode of 2P or P+S and C-my < 0. Published under an exclusive license by AIP Publishing.

Automated summary

The role of the added mass coefficient in vortex induced vibration is complex and elusive, but understanding the relationship between added mass and vibration patterns can help predict and prevent VIV. Studies on VIV of a long flexible cylinder and forced vibration of a rigid cylinder show that there is a correlation between the phase angle and negative added mass coefficients in the cross-flow direction, as well as the vortex shedding mode.