Improved In-Line VIV Prediction for Combined In-Line and Cross-Flow VIV Responses

Abstract

Slender marine structures are subjected to ocean currents, which can cause vortex-induced vibrations (VIV). Accumulated damage due to VIV can shorten the fatigue life of marine structures, so it needs to be considered in the design and operation phase. VIV prediction tools are based on hydrodynamic coefficients, which are obtained from forced motion experiments on a circular cylinder. Most of the forced motion experiments apply harmonic motions in either in-line (IL) or cross-flow (CF) direction. Combined IL and CF forced motion experiments are also reported. However, measured motions from flexible pipe VIV tests contain higher order harmonic components, which have not yet been extensively studied. This paper presents results from conventional forced motion VIV experiments, but using measured motions taken from a flexible pipe undergoing VIV. The IL excitation coefficients were used by semi-empirical VIV prediction software VIVANA to perform combined IL and CF VIV calculation. The key IL results are compared with NDP flexible pipe model test results. By using present IL excitation coefficients, the prediction of IL responses for combined IL and CF VIV responses is improved.

Review of pipeline span analysis

“…It was claimed that good predictions of IL response up to and beyond the start of CF response for the three test series in their study were achieved for the analyses with pure IL loading. (Yin, Passano, & Larsen, 2018), have shown that in the recently updated version of VIVANA, the prediction of IL responses for combined IL and CF VIV responses has been improved.…”

“…Recent works by Yin et al (2018) have shown that, in the recently updated version of VIVANA, the prediction of IL responses for combined IL and CF VIV responses has been improved.…”

“…VIVANA Predicts inline and cross flow forces (Passano et al, 2010). The model has been updated which now produces improved in-line VIV prediction for combined in-line and cross flow VIV responses (Yin et al, 2018).…”

Report of Committee III.2: Fatigue and fracture

“…CFD VIM or VIV results are validated versus experimental tests (Maximiano et al, 2017) that do not always predict accurately in situ observations (Koop et al, 2016). For risers, the VIV phenomena are mostly determined based on the empirical model (Ulveseter & Saevik, 2017, Yin et al, 2017 using the Morison equation, but the hydrodynamic parameters are directly calibrated based on tests measurements in a basin (Yin et al, 2015). The results from testing on regular waves with the results of a simulation of a Multi-Body System representing a floating wind turbine, loaded using Computational Fluid Dynamic software were compared in (Beyer et al, 2015).…”