An Empirical Model for Vortex-Induced Vibrations

Through an analytical-empirical approach, the vortex-excited transverse oscillations of flexibly-mounted circular cylinders in a uniform flow is studied. A new model is derived, assuming spanwise constant flow velocity within the sub-critical range of Reynolds numbers and using only experimental data obtained from forced cylinders in water. The steady-state response of flexibly-mounted cylinders is obtained as a function of the structural system and flow parameters and its stability is analyzed. Several characteristics observed experimentally and also present in the model response are discussed. The resultant model's capability for predicting structural response for a wide range of fluid mediums is illustrated through comparisons between model predictions and results obtained experimentally from flexibly-mounted cylinders in air and in water. This model developed is expected to yield better results for structures in water, by virtue of being based only on experimental results obtained in water.