| Summary: | The paper describes a new characterization of the properties of the vortex-induced vibrations (VIV) of marine risers, which emerges from processing field and experimental data. We show that two currently employed assumptions: (a) that VIV is a statistically steady-state response containing one or several frequencies, and (b) that VIV consists of alternating dominant modes (mode-sharing), are inadequate. Instead, we find that the response either contains strong traveling wave components accompanied by high force harmonics; or consists of a chaotic wandering among several traveling and standing waves, associated with a wide-band spectrum; both types of response require careful consideration for correct fatigue evaluation. Topics: Fatigue damage, Pipeline risers, Vortex-induced vibration BP-MIT Major Projects Program
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