LAUSR

Abstract Transverse vortex-induced vibration (VIV) of a two-dimensional, elliptic cylinder with various aspect ratios and stiffness is studied. The cylinder is elastically mounted and heated, and the flow direction is aligned with the direction of the thermal-induced buoyancy force. The transverse VIV can be suppressed as the thermal control parameter, the Richardson number ( R i ), increases. Complete suppression is achieved when  R i is above a critical value,  R i c . The critical  R i increases with the aspect ratio. For elliptic cylinders in lock-in regime,  R i c is the optimal value since both VIV suppression and the minimum drag are achieved. A maximum drag reduction of 50.2% was found for an aspect ratio (AR) 2 cylinder at  R i c . For VIV in the unsynchronized regime, even though the thermal control can suppress the vibration, the corresponding drag coefficient, however, can be higher than that in the case of without control. Therefore, the thermal control is more effective to suppress VIV in the lock-in regime. When suppressing the vibration of an AR 4 cylinder in the flexible VIV regime using thermal control, we observed the cross-2S vortex mode, in which the typical 2S vortices generated at near field can cross the centerline and switch sides after a few vibration cycles.