Hydrodynamic Forces and Coefficients on Flexible Risers Undergoing Vortex-Induced Vibrations in Uniform Flow

Song, Li; Fu, Shixiao; Zeng, Yadong; Chen, Yifan

doi:10.1061/(asce)ww.1943-5460.0000333

Cited by 19 publications

(9 citation statements)

References 20 publications

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“…ρ is the fluid density and D is the diameter of the riser. According to Song et al, the added mass coefficient C a varies along the riser's length significantly in both IL and CF directions (Song et al, 2016). In the present study, C a is taken as a constant and its variation is neglected.…”

Section: Nonlinear Coupled Structure and Wake Oscillator Modelmentioning

confidence: 92%

Predictions for combined In-Line and Cross-Flow VIV responses with a novel model for estimation of tension

Feng

Chen

et al. 2019

Ocean Engineering

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The dynamic responses of slender cylinders with high aspect ratios undergoing vortex-induced vibrations (VIV) are studied.In detail, a three-dimensional model predicting the VIV responses in both the In-Line and Cross-Flow directions of slender cylinders is proposed based on the nonlinear equation governing the dynamic deformation and a wake oscillator. The tension in the cylinder is estimated according to the incoming stream velocities. To predict the VIV responses, the cylinder is discretized into finite segments, and the vibrations of each segment are estimated from solving the governing equation when the excitation forces are modelled using the Van Der Pol's wake oscillator. Considering that the wake oscillator model estimates the excitation forces according to the dynamics of the cylinder, it reveals the interactions between the flow and the dynamics of the cylinder. In order to verify the model calculating the mean tension, the VIV responses, which has been experimentally tested, is numerically studied. The comparison between the numerically predicted and experimentally measured responses shows that, the approach, especially the novel tension model, proposed herein is reliable as the frequency

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Section: Nonlinear Coupled Structure and Wake Oscillator Modelmentioning

confidence: 92%

Predictions for combined In-Line and Cross-Flow VIV responses with a novel model for estimation of tension

Feng

Chen

et al. 2019

Ocean Engineering

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“…Inverse analysis is an effective method to extract hydrodynamic force coefficient from experiment with flexible cylinders using measured responses, (Wu, 2011, Wu, et al 2016c, Song, et al 2016. Significant improvement in VIV prediction with the obtained hydrodynamic data has been achieved (Wu, 2011).…”

Section: Introductionmentioning

confidence: 99%

VIV Responses of Riser With Buoyancy Elements: Forced Motion Test and Numerical Prediction

Lie

et al. 2017

Volume 2: Prof. Carl Martin Larsen and Dr. Owen Oakley Honoring Symposia on CFD and VIV

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Steel Lazy Wave Riser (SLWR) is an attractive deep water riser concept. When subjected to vortex induced vibrations (VIV), the vortex shedding process of the buoyancy element and the bare riser section will be different due to the difference in diameter. VIV responses can be strongly influenced by the dimension of the buoyancy element and its arrangement. Empirical VIV prediction programs, such as VIVANA, SHEAR7 and VIVA, are widely used by the industry for design against VIV loads. However, there is lack of hydrodynamic data to be used in these programs when buoyancy elements are present. Experiment to obtain hydrodynamic data for riser with staggered buoyancy elements was carried out in the towing tank in SINTEF Ocean. A rigid cylinder section with three staggered buoyancy elements was subjected to harmonic forced cross-flow (CF) motions. Hydrodynamic forces on one of the buoyancy elements were directly measured in addition to the measured forces at both ends of the test section. Two buoyancy element configurations were tested and the corresponding hydrodynamic data are compared with that of a bare cylinder. The obtained hydrodynamic data was also used in VIV prediction software and good prediction against existing flexible cylinder staggered buoyancy element VIV test data was achieved. A roadmap to achieve an optimal SLWR design by combining different experimental and numerical methods is suggested.

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“…VIV tests on flexible beams have been carried out [13] [14] [15]. In these tests, accelerometers and strain gauges are usually instrumented on the flexible beams, so that acceleration and bending strain are measured.…”

Section: Introductionmentioning

confidence: 99%

“…Hydrodynamic force calculated by inverse analysis can be used to enrich and improve the hydrodynamic coefficient database based on forced motion experiments. In [15], hydrodynamic forces were theoretically calculated by Euler-Bernoulli beam vibration equation, and the hydrodynamic coefficient were further investigated. Computational fluid dynamics (CFD) is a useful tool to understand the wake of flow and fluid-structure interaction.…”

Section: Introductionmentioning

confidence: 99%

Improved In-Line Vortex-Induced Vibrations Prediction for Combined In-Line and Cross-Flow Vortex-Induced Vibrations Responses

Yin

Passano

Larsen

2017

Journal of Offshore Mechanics and Arctic Engineering

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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. Semi-empirical VIV prediction tools are based on hydrodynamic coefficients. The hydrodynamic coefficients can either be calculated from experiments on flexible beams by using inverse analysis or theoretical methods, or obtained from forced motion experiments on a circular cylinder. Most of the forced motion experiments apply harmonic motions in either in-line (IL) or crossflow (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 Norwegian Deepwater Programme (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.

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Hydrodynamic Forces and Coefficients on Flexible Risers Undergoing Vortex-Induced Vibrations in Uniform Flow

Cited by 19 publications

References 20 publications

Predictions for combined In-Line and Cross-Flow VIV responses with a novel model for estimation of tension

Predictions for combined In-Line and Cross-Flow VIV responses with a novel model for estimation of tension

VIV Responses of Riser With Buoyancy Elements: Forced Motion Test and Numerical Prediction

Improved In-Line Vortex-Induced Vibrations Prediction for Combined In-Line and Cross-Flow Vortex-Induced Vibrations Responses

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