Coupling Between In-Line and Transverse VIV Response

Abstract

Most present-day programs for engineering prediction of VIV response are based on experimental lift and mass coefficients derived from 2D tests, where the cylinder has been constrained in in-line direction. The present paper describes a preliminary investigation into the coupling between in-line and transverse VIV response. A simple pendulum test set-up was used to study how the in-line response influenced the transverse one. For reduced velocities above 5, when the in-line oscillation frequency was exactly twice the transverse frequency, it was found that the transverse response was significantly reduced when allowing the cylinder to oscillate in both directions simultaneously, compared to the case when it was constrained in-line.