Flow force measurements and the wake transition in purely inline vortex-induced vibration of a circular cylinder

Flow-induced vibrations of a square prism free to oscillate in the cross-flow and inline directions

“…However, here two symmetric vortices are shed simultaneously from the two sides of the cylinder. This type of symmetric shedding has been observed before for VIV in the IL direction, when oscillations exist only in the IL direction (Cagney & Balabani 2014;Gurian, Currier & Modarres-Sadeghi 2019). The presence of these symmetric vortices here confirms that oscillations in the IL direction exist at this reduced velocity.…”

“…This reduced velocity is within the first range of non-zero-amplitude oscillations for a cylinder in pure IL VIV (Gurian et al. 2019). According to the IL VIV studies, the first range of oscillations is observed for , which corresponds to .…”

Resonance in vortex-induced in-line vibration at low Reynolds numbers

“…Considering that all three force coefficients, C dw , C d and C x1 , may be 'uniquely' specified in the parameter space A * : f * , this could suggest a single operating point inside this space at which a steady-state harmonic solution is feasible, which implies that the cylinder peak response is drawn towards this operating point irrespective of the mass ratio. Nonetheless, it should be cautioned that bimodal dynamics can also appear at particular regions of the parameter space A * : f * (Cagney & Balabani 2013a,b;Gurian et al 2019). Assuming that a unique solution exists at the resonance point, (4.8) illustrates that the component of the wake drag in-phase with the cylinder velocity counterbalances the quasi-steady drag, whereas (4.9) illustrates that the only contribution of the fluid force in-phase with the cylinder acceleration is the inviscid added-mass force.…”

“…Nonetheless, it should be cautioned that bimodal dynamics can also appear at particular regions of the parameter space (Cagney & Balabani 2013 a , b ; Gurian et al. 2019). Assuming that a unique solution exists at the resonance point, (4.8) illustrates that the component of the wake drag in-phase with the cylinder velocity counterbalances the quasi-steady drag, whereas (4.9) illustrates that the only contribution of the fluid force in-phase with the cylinder acceleration is the inviscid added-mass force.…”

“…at , has been attributed to the phasing of alternating vortex shedding, which provides a positive-damping, or negative-excitation force with respect to the oscillation of the cylinder (Konstantinidis, Balabani & Yianneskis 2005; Konstantinidis 2014). More recently, a mixed mode of combined symmetric and alternating vortex shedding was also reported to exist in-between the two branches (Gurian, Currier & Modarres-Sadeghi 2019).…”