2DOF CFD Calibrated Wake Oscillator Model to Investigate Vortex-Induced Vibrations

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Abstract

In this study a new two degrees-of-freedom wake oscillator model is proposed to describe vortex-inducedvibrations of elastically supported cylinders capable of moving in cross-flow and in-line directions. Totalhydrodynamic force acting on the cylinder is obtained here as a sum of lift and drag forces, which are definedas being proportional to the square of the magnitude of the relative flow velocity around the cylinder. Thetwo van der Pol type oscillators are then used to model fluctuating drag and lift coefficients. As the relativevelocity around the cylinder depends both on the fluid flow velocity and the velocity of the cylinder, theequations of motions of the cylinder in cross-flow and in-line directions become coupled through the fluidforces. It is shown that such approximation of the fluid forces allows to obtain the well known low dimensionalmodels in the limit case, and the model proposed by Facchinetti et al. [1] to describe the cross-flow vibrationsis used as an example. Experimental data and Computational Fluid Dynamics (CFD) results are used tocalibrate the proposed model and to verify the obtained predictions of complex fluid-structure interactionsfor different mass ratios. A number of phenomena such as the ”super-upper” branch, exclusive for a twodegrees-of-freedom motion at low mass ratios, are observed. Influence of the empirical parameters of thewake oscillators equations and fluid forces coefficients on the response is also discussed.
Original languageEnglish
Pages (from-to)176-190
Number of pages15
JournalInternational Journal of Mechanical Sciences
Volume127
Early online date24 May 2016
DOIs
Publication statusPublished - Jul 2017

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computational fluid dynamics
wakes
Computational fluid dynamics
Vortex flow
oscillators
vortices
vibration
cross flow
Flow velocity
Fluids
Drag
mass ratios
fluids
flow velocity
lift coefficients
Flow of fluids
drag coefficients
drag
fluid flow
degrees of freedom

Cite this

@article{ec49d2980665401d873af2ab20e0bcd1,
title = "2DOF CFD Calibrated Wake Oscillator Model to Investigate Vortex-Induced Vibrations",
abstract = "In this study a new two degrees-of-freedom wake oscillator model is proposed to describe vortex-inducedvibrations of elastically supported cylinders capable of moving in cross-flow and in-line directions. Totalhydrodynamic force acting on the cylinder is obtained here as a sum of lift and drag forces, which are definedas being proportional to the square of the magnitude of the relative flow velocity around the cylinder. Thetwo van der Pol type oscillators are then used to model fluctuating drag and lift coefficients. As the relativevelocity around the cylinder depends both on the fluid flow velocity and the velocity of the cylinder, theequations of motions of the cylinder in cross-flow and in-line directions become coupled through the fluidforces. It is shown that such approximation of the fluid forces allows to obtain the well known low dimensionalmodels in the limit case, and the model proposed by Facchinetti et al. [1] to describe the cross-flow vibrationsis used as an example. Experimental data and Computational Fluid Dynamics (CFD) results are used tocalibrate the proposed model and to verify the obtained predictions of complex fluid-structure interactionsfor different mass ratios. A number of phenomena such as the ”super-upper” branch, exclusive for a twodegrees-of-freedom motion at low mass ratios, are observed. Influence of the empirical parameters of thewake oscillators equations and fluid forces coefficients on the response is also discussed.",
author = "Andrey Postnikov and Ekaterina Pavlovskaia and Marian Wiercigroch",
note = "ACKNOWLEDGMENTS This work is supported by the National Subsea Research Institute (NSRI) UK.",
year = "2017",
month = "7",
doi = "10.1016/j.ijmecsci.2016.05.019",
language = "English",
volume = "127",
pages = "176--190",
journal = "International Journal of Mechanical Sciences",
issn = "0020-7403",
publisher = "Elsevier",

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TY - JOUR

T1 - 2DOF CFD Calibrated Wake Oscillator Model to Investigate Vortex-Induced Vibrations

AU - Postnikov, Andrey

AU - Pavlovskaia, Ekaterina

AU - Wiercigroch, Marian

N1 - ACKNOWLEDGMENTS This work is supported by the National Subsea Research Institute (NSRI) UK.

PY - 2017/7

Y1 - 2017/7

N2 - In this study a new two degrees-of-freedom wake oscillator model is proposed to describe vortex-inducedvibrations of elastically supported cylinders capable of moving in cross-flow and in-line directions. Totalhydrodynamic force acting on the cylinder is obtained here as a sum of lift and drag forces, which are definedas being proportional to the square of the magnitude of the relative flow velocity around the cylinder. Thetwo van der Pol type oscillators are then used to model fluctuating drag and lift coefficients. As the relativevelocity around the cylinder depends both on the fluid flow velocity and the velocity of the cylinder, theequations of motions of the cylinder in cross-flow and in-line directions become coupled through the fluidforces. It is shown that such approximation of the fluid forces allows to obtain the well known low dimensionalmodels in the limit case, and the model proposed by Facchinetti et al. [1] to describe the cross-flow vibrationsis used as an example. Experimental data and Computational Fluid Dynamics (CFD) results are used tocalibrate the proposed model and to verify the obtained predictions of complex fluid-structure interactionsfor different mass ratios. A number of phenomena such as the ”super-upper” branch, exclusive for a twodegrees-of-freedom motion at low mass ratios, are observed. Influence of the empirical parameters of thewake oscillators equations and fluid forces coefficients on the response is also discussed.

AB - In this study a new two degrees-of-freedom wake oscillator model is proposed to describe vortex-inducedvibrations of elastically supported cylinders capable of moving in cross-flow and in-line directions. Totalhydrodynamic force acting on the cylinder is obtained here as a sum of lift and drag forces, which are definedas being proportional to the square of the magnitude of the relative flow velocity around the cylinder. Thetwo van der Pol type oscillators are then used to model fluctuating drag and lift coefficients. As the relativevelocity around the cylinder depends both on the fluid flow velocity and the velocity of the cylinder, theequations of motions of the cylinder in cross-flow and in-line directions become coupled through the fluidforces. It is shown that such approximation of the fluid forces allows to obtain the well known low dimensionalmodels in the limit case, and the model proposed by Facchinetti et al. [1] to describe the cross-flow vibrationsis used as an example. Experimental data and Computational Fluid Dynamics (CFD) results are used tocalibrate the proposed model and to verify the obtained predictions of complex fluid-structure interactionsfor different mass ratios. A number of phenomena such as the ”super-upper” branch, exclusive for a twodegrees-of-freedom motion at low mass ratios, are observed. Influence of the empirical parameters of thewake oscillators equations and fluid forces coefficients on the response is also discussed.

U2 - 10.1016/j.ijmecsci.2016.05.019

DO - 10.1016/j.ijmecsci.2016.05.019

M3 - Article

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EP - 190

JO - International Journal of Mechanical Sciences

JF - International Journal of Mechanical Sciences

SN - 0020-7403

ER -