Time-Domain Analysis of Motion-Induced Vibrations Validated by Experimental Measurements

Abstract Concurrent wave and vortex-induced vibration (VIV) loads, along with platform motion-induced vibrations for marine risers and subsea power cables, lack sufficient understanding. The evaluation of fatigue damage under simultaneously acting loads is often simplified when using frequency-domain tools. The time-domain load model, VIVANA-TD, has been developed as part of the Lazy Wave Riser Joint Industry Project. This model extends the Morison equation by incorporating vortex shedding force terms. Its synchronization model introduces phase coupling between the force and response, effectively capturing how the local vortex shedding frequency adjusts to achieve lock-in. The model's advancements in handling structural non-linearities and time-varying flows improve VIV predictions. This study validates the combined cross-flow and in-line time-domain VIV load model using data from Equinor's truncated steel catenary riser (SCR) and steel lazy wave riser (SLWR) model tests. The results show that the predicted maximum fatigue damage is within a factor of 5 of the measured values in most cases. This demonstrates that VIVANA-TD accurately captures the key characteristics of VIV responses under oscillatory flow conditions. The findings enhance understanding of VIV driven by platform motions, with practical implications for both the Oil & Gas and renewable energy sectors.