Vortex-induced vibrations model with 2 degrees of freedom of rigid cylinders near a plane boundary based on wake oscillator

Vortex-Induced Vibrations Of A Pipeline Near The Sea Floor

“…In this work is used the wake oscillator model developed by Fehér and Avila [6] to simulate the VIV of rigid cylinders on the proximity of a plane boundary. Such model emerged as a modification on the model of Facchinetti et al for cylinders purely affected by VIV, which is based upon the van der Pol equation.…”

“…For the effect of the plane boundary, Fehér and Avila added three new terms, that are gap ratio e/D dependant, to the Facchinetti model of Eq. ( 4) [6], obtaining, q + ϵω s (q 2 − 1) q + (ω 2 s + ψ(e/D)ω s ω n )q = β(e/D)…”

“…The other approach is based on a wake oscillator model, often the van der Pol equation, that can accurately represent the fluid interaction with the structure for 1 or 2 degrees of freedom (DOF), thus it has been used, notably as by Facchinetti et al [4] and Ogink and Metrikine [5] to predict the the fluid-structure interaction of a purely VIV affected cylinder, yet the influence of a boundary has not been considered on those studies. Fehér and Avila [6] proposes the addition of three new empirical coefficients, obtained through polynomial regression, to the wake equation, so that the interference of the boundary on the fluid-structure interaction is taken into account.…”

“…In such manner, the present work proposes a numerical model capable to simulate the dynamic behavior of a flexible pipeline under a free-stream near a plane boundary in representation of the seabed with variable gap ratios. This model only considers the pipeline's vibration for 1-DOF in the direction transverse to the current, the crossflow direction, and is based on a wake oscillator proposed by Fehér and Avila [6] for larger and medium gap ratios, the small gap ratios where the pipeline may thouch the sea floor is not taken into account. The structural damping is not considered due to its small influence over the vibration when compared to the effects of excitation of the lift force.…”

Motion-amplitude-dependent nonlinear VIV model and maximum response over a full-bridge span

“…It has been extended from 1-DOF systems where only across-wind body motion is considered [12][13], to 2-DOF systems where both across-wind and streamwise body motions are included [14][15][16][17][18]. In terms of the specific body motions coupled, they can be divided into models coupled with velocity [10,[19][20][21], acceleration [16], or a mix of velocity and acceleration [22]. Moreover, this type of models have been adapted to forced oscillations [23][24].…”