Abstract
In this study a new two degreesoffreedom wake oscillator model is proposed to describe vortexinduced vibrations of elastically supported cylinders capable of moving in crossflow and inline directions. Total hydrodynamic force acting on the cylinder is obtained here as a sum of lift and drag forces, which are defined as being proportional to the square of the magnitude of the relative flow velocity around the cylinder. The two van der Pol type oscillators are then used to model fluctuating drag and lift coefficients. As the relative velocity around the cylinder depends both on the fluid flow velocity and the velocity of the cylinder, the equations of motions of the cylinder in crossflow and inline directions become coupled through the fluid forces. It is shown that such approximation of the fluid forces allows to obtain the well known low dimensional models in the limit case, and the model proposed by Facchinetti et al. [1] to describe the crossflow vibrations is used as an example. Experimental data and Computational Fluid Dynamics (CFD) results are used to calibrate the proposed model and to verify the obtained predictions of complex fluidstructure interactions for different mass ratios. A number of phenomena such as the ”superupper” branch, exclusive for a two degreesoffreedom motion at low mass ratios, are observed. Influence of the empirical parameters of the wake oscillators equations and fluid forces coefficients on the response is also discussed.
Original language  English 

Pages (fromto)  176190 
Number of pages  15 
Journal  International Journal of Mechanical Sciences 
Volume  127 
Early online date  24 May 2016 
DOIs  
Publication status  Published  1 Jul 2017 
Bibliographical note
ACKNOWLEDGMENTSThis work is supported by the National Subsea Research Institute (NSRI) UK.
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Ekaterina Pavlovskaia
 Engineering, Engineering  Head of School of Engineering, Personal Chair
 Engineering, Centre for Applied Dynamics Research (CADR)
Person: Academic