Empirical tuning of the van der Pol wake oscillator model coupled with a 1DOF cylinder undergoing

Experimental vortex induced vibration data collected for 3 < U* < 11, m*zeta = 0.04, and Re = 4000, is used for tuning a coupled van der Pol wake oscillator and mass-spring-damper system. In the past, the coupled model is often evaluated in comparison to a small set of experimental data and fixed values for the tuning parameters are chosen for a range of reduced velocities. Rather than tuning each equation to a data set, in this study we explore the behavior of the coupled equation and its tuning parameters, including the selected stationary lift coefficient (Clo). The coupled model is evaluated over a parameter space of the nonlinear damping parameter, ε, and coupling parameter, β. Each calculated response is compared to experimental data to generate an error surface. The results show that the selected lift coefficient together with the tuning parameters enables manipulation of the maximum amplitude and range of synchronization. The error surfaces show large ranges where tuning parameters may be used to obtain a reasonable fit to experimental data. Furthermore, for each reduced velocity, there is unique set of ε and β that provide a best fit to the experimental displacement, indicating a dependance on the reduced velocity.