Hydrodynamic Force Identification From Vortex Induced Vibration Experiments With Slender Beams

The characteristics of hydrodynamic forces are much more complicated for a long flexible cylinder under vortex induced vibration (VIV) than that for a rigid pipe. However, it is difficult to get force measurement directly from experiment with flexible beams. The dynamic behavior of the cylinder under VIV is recorded by accelerometers or transducers for bending moment measurement along the cylinder. The present work provides a modal approach to estimate the hydrodynamic force from measurement. The method is able to estimate the force at the fundamental vortex shedding frequency and the third order harmonic force component as well.