The Occurrence of Lock-in Under Highly Sheared Conditions

Vandiver, J. Kim; Allen, Don; Li, Li

doi:10.1006/jfls.1996.0037

Cited by 53 publications

(28 citation statements)

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“…11 highlights the occurrence of lock-in condition in riser VIV subject to linearly sheared flow. This justifies the model assumption of s,max ≈ ω n (Section 2.2) and confirms the lock-in event observed in the literature based on experimental (Tognarelli et al 2004;Vandiver et al 1996) and CFD (Lucor et al 2001) results.…”

Section: Time Histories Oscillating Frequencies and Lock-in Occurrencesupporting

confidence: 90%

“…1), some relevant experimental observations are summarized as follows. Based on a 3.66 m long cylinder exposed to flow, Vandiver et al (1996) showed how a single-mode or multi-mode response occurs under different sheared flow conditions and that the occurrence of lock-in or non-lock-in depends both on the number of potentially excited modes and the shear parameter. Tognarelli et al (2004) analyzed a 10 m long tested pipe responding in low-mode VIV and showed the validity of some common modelling assumptions providing a good qualitative description of VIV characters.…”

Section: Introductionmentioning

confidence: 99%

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Analysis and prediction of vortex-induced vibrations of variable-tension vertical risers in linearly sheared currents

Srinil

2011

Applied Ocean Research

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Many studies have tackled the problem of vortex-induced vibrations (VIV) of a vertical riser with a constant tension and placed in uniform currents. In this study, attention is focused on the cross-flow VIV modelling, time-domain analysis and prediction of variable-tension vertical risers in linearly sheared currents. The partial-differential equation governing the riser transverse motion is based on a flexural tensioned-beam model with typical pinned-pinned supports. The hydrodynamic excitation model describing the modulation of lift force is based on a distributed van der Pol wake oscillator whose nonlinear equation is also partial-differential due to the implementation of a diffusion term. The variation of empirical wake coefficients with system parameters and the water depth-dependent Reynolds number is introduced. Based on the assumed Fourier mode shape functions obtained by accounting for the effect of nonuniform tension, the Galerkin technique is utilized to construct a low-dimensional multi-mode model governing the coupled fluid-riser interaction system due to VIV. Numerical simulations in the case of varying sheared flow profiles are carried out to systematically evaluate riser nonlinear dynamics and highlight the influence of fluid-structure parameters along with associated VIV aspects. In particular, the effects of shear and tensioned-beam (tension versus bending) parameters are underlined. Some comparisons with published experimental results and observations are qualitatively and quantitatively discussed. Overall parametric analysis and prediction results may be worthwhile for being a new benchmark against future experimental testing and/or numerical results predicted by an alternative model and methodology.

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Section: Time Histories Oscillating Frequencies and Lock-in Occurrencesupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Analysis and prediction of vortex-induced vibrations of variable-tension vertical risers in linearly sheared currents

Srinil

2011

Applied Ocean Research

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show abstract

“…Kim et al (1985) report multi-moded nonlock-in behavior in shear #ows. More recently, Vandiver et al (1996) have reported the existence of regimes of lock-in and nonlock-in response in highly sheared #ows. Research into vortex-excited vibrations in nonuniform #ow is still in its infancy and, given the growing demand for oil exploration in deeper waters, a better quantitative understanding of the e!ect of shear in the #ow on vortex-excited vibrations is essential.…”

Section: Introductionmentioning

confidence: 98%

Vortex-Excited Vibrations of Uniform Pivoted Cylinders in Uniform and Shear Flow

Balasubramanian

Skop

Haan

et al. 2000

Journal of Fluids and Structures

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“…Later experiments by Peltzer and Rooney (1981) with 0( (0)026, and Peltzer (1982) reported a spanwise variation of base pressure, but seemingly without a relationship to a cellular pattern. Vandiver et al (1996) studied the phenomenon of lock-in under highly sheared conditions. They found that, when the shear is high, lock-on was likely to occur because of the dominance of a single mode of vortex shedding over other modes.…”

Section: Introductionmentioning

confidence: 99%

Computation of Force on a Cylinder in a Shear Flow

Dalton

2001

Journal of Fluids and Structures

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The Occurrence of Lock-in Under Highly Sheared Conditions

Cited by 53 publications

References 0 publications

Analysis and prediction of vortex-induced vibrations of variable-tension vertical risers in linearly sheared currents

Analysis and prediction of vortex-induced vibrations of variable-tension vertical risers in linearly sheared currents

Vortex-Excited Vibrations of Uniform Pivoted Cylinders in Uniform and Shear Flow

Computation of Force on a Cylinder in a Shear Flow

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