The Lock-in Phenomenon in VIV using A Modified Wake Oscillator Model for both High and Low Mass-Damping Ratio

In the present paper the behavior of an elastically mounted cylinder in low and high mass-damping ratio is investigated. For high mass-damping ratio, a classical wake oscillator model is used. At the first, by neglecting all damping and nonlinear terms of this model, the possibility of using a linear model for determination of the lock-in range and the dominant mode is investigated. Then, without neglecting any terms, the nonlinear model is analyzed and the results are compared with experimental results. Due to change of the behavior of the system in low mass-damping ratio and disability of classic model in modeling of this change, a modified wake oscillator model is presented and the results ofthis model, in both low and high mass-damping ratio, are compared with experimental results