A simplified method for time domain simulation of cross-flow vortex-induced vibrations

Thorsen, Mats Jørgen; Sævik, Svein; Larsen, Carl M.

doi:10.1016/j.jfluidstructs.2014.04.006

Cited by 61 publications

(38 citation statements)

References 21 publications

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“…The power loss based on Vikestad's measurements and the present model is shown in figure 2. The results from the old damping model (Thorsen et al, 2014a) is also shown, and it is seen that the new model provides much better agreement with the experiment. To investigate the performance when U = 0, the model is used to simulate the hydrodynamic damping force on a cylinder oscillating in the cross-flow direction with frequency f at a reduced velocity, U r = U/(f D) of 3 and 10, which is below and above the positive excitation zone respectively.…”

Section: Cross-flow Hydrodynamic Forcementioning

confidence: 86%

“…In addition, there will be fluid resistance (damping) and added mass effects due to the velocity and acceleration of the cylinder. The hydrodynamic force model used here was first presented by Thorsen et al (2014a). Some minor modifications were introduced (Thorsen et al, 2015), providing the starting point for the present paper.…”

Section: Hydrodynamic Force Modelmentioning

confidence: 99%

“…An alternative method for simulating VIV in time domain was proposed by Thorsen et al (2014a). In this semi-empirical method, the fluid forces are calculated based on the incoming flow velocity and the motion of the cross-section.…”

Section: Introductionmentioning

confidence: 99%

“…The special feature is how synchronization between the vortex shedding and cylinder motion is taken into account. It has been shown that the model provides realistic results for several different cases, including flexible cylinders in uniform, sheared and stepped current (Thorsen et al, 2014b(Thorsen et al, , 2015. The formulation includes no restriction on the time variability of the incoming flow velocity, which means it is theoretically suited for simulating VIV in oscillating flows.…”

Section: Introductionmentioning

confidence: 99%

“…The formulation includes no restriction on the time variability of the incoming flow velocity, which means it is theoretically suited for simulating VIV in oscillating flows. With this in mind, the outline of the present paper is as follows: Firstly, the original model (Thorsen et al, 2014a) is slightly modified to improve the prediction accuracy in stationary flows. Secondly, the improved model is used to simulate a flexible cylinder in oscillating flow.…”

Section: Introductionmentioning

confidence: 99%

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Time domain simulation of vortex-induced vibrations in stationary and oscillating flows

Thorsen

Sævik

Larsen

2016

Journal of Fluids and Structures

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This paper focuses on the further development of a previously published semi-empirical method for time domain simulation of vortex-induced vibrations (VIV). A new hydrodynamic damping formulation is given, and the necessary coefficients are found from experimental data. It is shown that the new model predicts the observed hydrodynamic damping in still water and for cross-flow oscillations in stationary incoming flow with high accuracy. Next, the excitation force model is optimized by simulating the VIV response of an elastic cylinder in a series of experiments with stationary flow. The optimization is performed by repeating the simulations until the best possible agreement with the experiments is found. The optimized model is then applied to simulate the cross-flow VIV of an elastic cylinder in oscillating flow, without introducing any changes to the hydrodynamic force modeling. By comparison with experiment, it is shown that the model predicts the frequency content, mode and amplitude of vibration with a high level of realism, and the amplitude modulations occurring at high Keulegan-Carpenter numbers are well captured. The model is also utilized to investigate the effect of increasing the maximum reduced velocity and the mass ratio of the elastic cylinder in oscillating flow. Simulations show that complex response patterns with multiple modes and frequencies appear when the maximum reduced velocity is increased. If, however, the mass ratio is increased by a factor of 5, a single mode dominates. This illustrates that, in oscillating flows, the mass ratio is important in determining the mode participation at high maximum reduced velocities.

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Section: Cross-flow Hydrodynamic Forcementioning

confidence: 86%

Section: Hydrodynamic Force Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Time domain simulation of vortex-induced vibrations in stationary and oscillating flows

Thorsen

Sævik

Larsen

2016

Journal of Fluids and Structures

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Data-Driven Prediction of Vortex-Induced Vibration Response of Marine Risers Subjected to Three-Dimensional Current

Riemer-Sørensen

Lie

et al. 2019

Communications in Computer and Information Science

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Slender marine structures such as deep-water marine risers are subjected to currents and will normally experience Vortex Induced Vibrations (VIV), which can cause fast accumulation of fatigue damage. The ocean current is often three-dimensional (3D), i.e., the direction and magnitude of the current vary throughout the water column. Today, semi-empirical tools are used by the industry to predict VIV induced fatigue on risers. The load model and hydrodynamic parameters in present VIV prediction tools are developed based on two-dimensional (2D) flow conditions, as it is challenging to consider the effect of 3D flow along the risers. Accordingly, the current profiles must be purposely made 2D during the design process, which leads to significant uncertainty in the prediction results. Further, due to the limitations in the laboratory, VIV model tests are mostly carried out under 2D flow conditions and thus little experimental data exist to document VIV response of riser subjected to varying directions of the current. However, a few experiments have been conducted with 3D current. We have used results from one of these experiments to investigate how well 1) traditional and 2) an alternative method based on a data driven prediction can describe VIV in 3D currents. Data driven modelling is particularly suited for complicated problems with many parameters and non-linear relationships. We have applied a data clustering algorithm to the experimental 3D flow data in order to identify measurable parameters that can influence responses. The riser responses are grouped based on their statistical characteristics, which relate to the direction of the flow. Furthermore we fit a random forest regression model to the measured VIV response and compare its performance with the predictions of existing VIV prediction tools (VIVANA-FD).

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Understanding vortex-induced vibration characteristics of a long flexible marine riser by a bidirectional fluid–structure coupling method

et al. 2019

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A simplified method for time domain simulation of cross-flow vortex-induced vibrations

Cited by 61 publications

References 21 publications

Time domain simulation of vortex-induced vibrations in stationary and oscillating flows

Time domain simulation of vortex-induced vibrations in stationary and oscillating flows

Data-Driven Prediction of Vortex-Induced Vibration Response of Marine Risers Subjected to Three-Dimensional Current

Understanding vortex-induced vibration characteristics of a long flexible marine riser by a bidirectional fluid–structure coupling method

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