Blind predictions of laboratory measurements of vortex-induced vibrations of a tension riser

Abstract

This paper compares laboratory measurements of the vortex-induced vibrations of a riser in a stepped current with blind predictions obtained with 11 different numerical models. Results are included on in-line and transverse displacements and curvatures, and dominant frequencies. In general, empirical models were more successful at predicting cross-flow displacements and curvatures than current codes based on CFD. Overall ratios between predictions and measurements of cross-flow displacements were around 95% and 75%, respectively. Predictions of cross-flow curvatures were more scattered, and almost all were unconservative. In-line vortex-induced curvatures, which may cause as much damage as cross-flow curvatures, could not be computed by any of the empirically based codes, and in general those based on CFD were in very poor agreement with the measurements.