A Wiener-Laguerre model of VIV forces given recent cylinder velocities

TL;DR

This paper introduces a time domain VIV force model using Wiener-Laguerre filtering to better capture chaotic vibrations and interactions in slender structures, with promising results but requiring further stability analysis.

Contribution

A novel Wiener-Laguerre based time domain model for VIV forces that captures chaotic dynamics and interactions, advancing beyond traditional frequency domain models.

Findings

Model provides realistic vibration simulations

Unphysical patterns observed in some cases

Further work needed on orbit stability

Abstract

Slender structures immersed in a cross flow can experience vibrations induced by vortex shedding (VIV), which cause fatigue damage and other problems. VIV models in engineering use today tend to operate in the frequency domain. A time domain model would allow to capture the chaotic nature of VIV and to model interactions with other loads and non-linearities. Such a model was developed in the present work: for each cross section, recent velocity history is compressed using Laguerre polynomials. The compressed information is used to enter an interpolation function to predict the instantaneous force, allowing to step the dynamic analysis. An offshore riser was modeled in this way: Some analyses provided an unusually fine level of realism, while in other analyses, the riser fell into an unphysical pattern of vibration. It is concluded that the concept is promissing, yet that more work is needed to understand orbit stability and related issues, in order to further progress towards an engineering tool.