Vortex-induced vibrations model with 2 degrees of freedom of rigid cylinders near a plane boundary based on wake oscillator

2021 ◽  
pp. 108938
Author(s):  
Rafael Fehér ◽  
J.P.J. Avila
Keyword(s):  
Degrees Of Freedom ◽  
Plane Boundary ◽  
Wake Oscillator ◽  
Vortex Induced Vibrations

scholarly journals Optimal energy harvesting from vortex-induced vibrations of cables

2016 ◽  
Vol 472 (2195) ◽  
pp. 20160583 ◽  
Author(s):  
G. O. Antoine ◽  
E. de Langre ◽  
S. Michelin
Keyword(s):  
Energy Harvesting ◽  
Flow Velocity ◽  
Passive Control ◽  
Optimal Harvesting ◽  
Control Mechanisms ◽  
Wake Oscillator ◽  
Vortex Induced Vibrations ◽  
Harvesting Systems ◽  
Gradient Based ◽  
Flexible Cables

Vortex-induced vibrations (VIV) of flexible cables are an example of flow-induced vibrations that can act as energy harvesting systems by converting energy associated with the spontaneous cable motion into electricity. This work investigates the optimal positioning of the harvesting devices along the cable, using numerical simulations with a wake oscillator model to describe the unsteady flow forcing. Using classical gradient-based optimization, the optimal harvesting strategy is determined for the generic configuration of a flexible cable fixed at both ends, including the effect of flow forces and gravity on the cable’s geometry. The optimal strategy is found to consist systematically in a concentration of the harvesting devices at one of the cable’s ends, relying on deformation waves along the cable to carry the energy towards this harvesting site. Furthermore, we show that the performance of systems based on VIV of flexible cables is significantly more robust to flow velocity variations, in comparison with a rigid cylinder device. This results from two passive control mechanisms inherent to the cable geometry: (i) the adaptability to the flow velocity of the fundamental frequencies of cables through the flow-induced tension and (ii) the selection of successive vibration modes by the flow velocity for cables with gravity-induced tension.

Three-dimensional vortex-induced vibrations of a circular cylinder predicted using a wake oscillator model

2021 ◽  
Vol 80 ◽  
pp. 103078
Author(s):  
Yun Gao ◽  
Zhuangzhuang Zhang ◽  
Ganghui Pan ◽  
Geng Peng ◽  
Lei Liu ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Three Dimensional ◽  
Oscillator Model ◽  
Wake Oscillator Model ◽  
Wake Oscillator ◽  
Vortex Induced Vibrations

The Numerical Research of Two-Degrees-of-Freedom Vortex-Induced Vibrations of Circular Cylinders

2012 ◽  
Vol 204-208 ◽  
pp. 4598-4601
Author(s):  
Jie Li Fan ◽  
Wei Ping Huang
Keyword(s):  
Degrees Of Freedom ◽  
Amplitude Ratio ◽  
Flow Direction ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Two Degrees Of Freedom ◽  
Line Frequency ◽  
Ansys Cfx ◽  
Vortex Induced Vibrations ◽  
Lock In

The two-degrees-of-freedom of vortex-induced vibration of circular cylinders is numerically simulated with the software ANSYS/CFX. The VIV characteristic, in the two different conditions (A/D=0.07 and A/D=1.0), is analyzed. When A/D is around 0.07, the amplitude ratio of the cylinder’s VIV between in-line and cross-flow direction in the lock-in is lower than that in the lock-out. The in-line frequency is twice of that in cross-flow direction in the lock-out, but in the lock-in, it is the same as that in cross-flow direction and the same as that of lift force. When A/D is around 1.0, the amplitude ratio of the VIV between in-line and cross-flow in the lock-in is obviously larger than that in the lock-out. Both in the lock-in and in the lock-out, the in-line frequency is twice of that in cross-flow direction.

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