Numerical simulation of two-degree-of-freedom vortex-induced vibration of a circular cylinder close to a plane boundary

2011 ◽  
Vol 27 (7) ◽  
pp. 1097-1110 ◽  
Author(s):  
Ming Zhao ◽  
Liang Cheng
Keyword(s):  
Numerical Simulation ◽  
Circular Cylinder ◽  
Degree Of Freedom ◽  
Plane Boundary ◽  
Vortex Induced Vibration ◽  
Two Degree Of Freedom

Numerical Investigation of Vortex-Induced Vibration of a Circular Cylinder Close to a Plane Boundary

2010 ◽  
Author(s):  
Ming Zhao ◽  
Liang Cheng
Keyword(s):  
Experimental Data ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Degree Of Freedom ◽  
Plane Boundary ◽  
Structural Dynamic ◽  
Vortex Induced Vibration ◽  
Two Degree Of Freedom ◽  
Bounce Back

Two-degree of freedom vortex-induced vibration (VIV) of a circular cylinder close to a plane boundary is investigated numerically. Two-dimensional (2D) Reynolds-Averaged Navier-Stokes Equations (RANS) and structural dynamic equation are solved using a finite element method (FEM). If the cylinder is initially very close to the plane boundary, it will be bounced back after it collides with boundary. It is assumed that the bouncing back only alters the cylinder’s velocity component perpendicular to the boundary. After it is bounced back, the cylinder’s velocity are determined by Uc = Uc′, Vc = −bVc′, where Uc and Vc are the cylinder’s velocity parallel to the boundary and that perpendicular to the boundary respectively, Uc′ and Vc′ are the velocities before cylinder is bounced back, b is the bounce back coefficient which is between 0 and 1. Numerical results of the vibration amplitude and frequency of a one-degree-of-freedom vibration (transverse to flow direction) of a circular cylinder close to a plane boundary are compared with the experimental data by Yang et al. [1]. The overall trends of the variation of the VIV amplitude with the reduced velocity were found to be in agreement with the experimental results. The calculated amplitude is smaller than the measured data. The frequency of the vibration increases with the increase of reduced velocity. The calculated vibrating frequency agrees well with the experimental data. It was found in this study that vortex-induced vibration (VIV) occurs even when the gap between the cylinder and the plane boundary is zero. This contradicts a perception that VIV would not occur for a pipeline close to the seabed with a gap ratio smaller than 0.3, this is because it was understood that vortex shedding would have been suppressed if the gap between the cylinder and the plane boundary is less than about 0.3 times of cylinder diameter for a fixed cylinder. Two-degree-of-freedom VIV of a circular cylinder close to a plane boundary is studied. The XY-trajectories, the frequency and the amplitude of the vibration are studied. The effects of the cylinder-to-boundary gap and the bounce back coefficient on VIV and the link between the vortex shedding mode and the VIV are discussed.

Numerical Study of the Influence of Initial Condition in Vortex Induced Vibration of a Circular Cylinder With Two Degree of Freedom

2011 ◽  
Author(s):  
Bruno C. Ferreira ◽  
Marcelo A. Vitola ◽  
Juan B. V. Wanderley ◽  
Sergio H. Sphaier
Keyword(s):  
Circular Cylinder ◽  
Stokes Equations ◽  
Numerical Study ◽  
Cross Flow ◽  
Degree Of Freedom ◽  
Curvilinear Coordinates ◽  
Initial Condition ◽  
Ocean Engineering ◽  
Vortex Induced Vibration ◽  
Two Degree Of Freedom

The vortex-induced vibration (VIV) is a classical problem in ocean engineering. Intensive research on this field for flow around a circular cylinder has been observed, due to practical application, mainly the design of risers, cables and pipelines with free span. The relevance of this phenomenon is related to the structure failure, consequence of large displacement or fatigue. In the present study the influence of initial condition on the vortex induced vibration (VIV) of a circular cylinder with two degree of freedom is investigated by the numerical solution of the slightly compressible formulation of Reynolds Average Navier-Stokes equations. An upwind and Total Variation Diminishing (TVD) conservative scheme is used to solve the governing equations written in curvilinear coordinates. The k–ε turbulence model is used to simulate the turbulent flow in the wake of the cylinder. Two different initial conditions have been tested, free-stream and continuous reduced velocity increase (using the previous reduced velocity as initial condition for the next value). Results for the phase angle, amplitude, frequency, and lift coefficient are presented. The numerical results have been compared with experimental data of Jauvtis and Williamson [1]. The results indicate that the history of cylinder movement has a important impact in the amplitude oscillation observed in-line and cross-flow, principally in the reduced velocity range associated with the upper branch. Results obtained for the initial and lower branch seems to be independent of the initial condition. Further investigation are necessary to understand the difference observed such as the absence of the jump in the cross-flow oscillation between the initial and upper branch and the absence of in-line oscillation for reduced velocity in the range of 1–4 and the peak of in-line oscillation at reduced velocity 6.0.

Numerical Simulation of Two-Degree-of-Freedom Vortex-Induced Vibration of a Circular Cylinder Between Two Lateral Plane Walls in Steady Currents

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Ming Zhao ◽  
Feifei Tong ◽  
Liang Cheng
Keyword(s):  
Numerical Simulation ◽  
Circular Cylinder ◽  
Mass Ratio ◽  
Vortex Induced Vibration ◽  
Lateral Plane ◽  
Low Mass ◽  
Low Mass Ratio ◽  
Lock In ◽  
Two Degree Of Freedom ◽  
Lateral Walls

Vortex-induced vibration (VIV) of a circular cylinder at a low mass ratio of 1.5 between two lateral walls is investigated numerically. The focus of the study is to examine the effects of the two lateral walls on the VIV. Numerical simulations are carried out for w/D = 4, 6, 10, and 20 with D and w being the cylinder diameter and the distance between the two walls, respectively. It is found that the effects of the two walls on the VIV are obvious as w/D ≤ 6 and negligibly small as w/D = 10. The VIV amplitudes in both x- and y-directions increase with the increasing w/D in the lock-in regime.

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