Time Domain FEA for Riser VIV Analysis

Abstract

Risers are often subjected to non-linear boundary conditions, such as soil-SCR interaction and interaction between risers and the guides in the vessel, which often have gaps and non-linear stiffness. Also, current profiles may vary in direction through depth. In these cases, time domain FEA could represent the problems better than frequency domain analysis. Several computer codes are available for cross-flow VIV analysis using time domain FEA. This paper introduces SimVIV, a time domain computer code for cross-flow VIV and in-line VIV analysis. The algorithm used in SimVIV for cross-flow VIV analysis is consistent to the one used in the Highly Compliant Rigid Riser Joint Industry Project (HCR Riser JIP). The algorithm for in-line VIV is an added feature in this code, and for this initial attempt, this covers only in-line VIV that has about twice the frequency of the cross-flow VIV. This paper presents the results of SimVIV to predict cross-flow VIV and in-line VIV for model tests that have been done at the Delta Flume of Delft Hydraulics (May 2003). The results in general show good comparison to the measured data.