scholarly journals Two-Dimensional Coupled Vortex-Induced Vibration of Circular Cylinder: Prediction and Extraction of Hydrodynamics Properties

2013 ◽  
Author(s):  
Hossein Zanganeh ◽  
Narakorn Srinil
Keyword(s):  
Circular Cylinder ◽  
Numerical Solutions ◽  
Cross Flow ◽  
Structural Equations ◽  
Experimental Results ◽  
High Mass ◽  
Two Dimensional ◽  
Fluid Structure ◽  
Vortex Induced Vibration ◽  
Proposed Model

An advanced model for predicting a two-dimensional coupled cross-flow and in-line vortex-induced vibration (VIV) of a flexibly-mounted circular cylinder in a uniform flow is proposed and investigated. Attention is placed on a systematic extraction of variable hydrodynamics properties associated with a bi-directional fluid-structure interaction system. The governing equations of motion are based on double Duffing-van der Pol (structural-wake) oscillators with the two structural equations containing cubic and quadratic nonlinear terms. The cubic nonlinearities capture the geometrical coupling of cross-flow/in-line displacements excited by hydrodynamic lift/drag forces whereas the quadratic nonlinearities allow fluid-structure interactions. The combined analytical and numerical solutions of the proposed model are established. By varying flow velocities in numerical simulations, the derived low-order model qualitatively captures several key VIV characteristics of coupled in-line/cross-flow oscillations. By making use of a newly-derived empirical formula, the predicted maximum cross-flow/in-line VIV amplitudes and associated lock-in ranges compare well with several experimental results for cylinders with low/high mass or damping ratios. Moreover, such important hydrodynamic properties as VIV-induced mean drag, added mass, excitation and damping terms can be systematically determined via the proposed model and compared well with some experimental results in the literature.

Force Evolution Model for Vortex-Induced Vibration of an Elastic Cylinder in a Cross Flow

2006 ◽  
Author(s):  
X. Q. Wang ◽  
W.-C. Xie ◽  
R. M. C. So
Keyword(s):  
Steady Flow ◽  
Fluid Structure Interaction ◽  
Cross Flow ◽  
Elastic Cylinder ◽  
Evolution Model ◽  
Evolution Process ◽  
Fluid Structure ◽  
Vortex Induced Vibration ◽  
Structure Interaction ◽  
Proposed Model

Vortex-induced vibration of a single circular cylinder is a fundamental and significant case of flow-induced vibrations in both engineering practice and academic research. A force evolution model is developed for vortex-induced vibration of an elastic cylinder in a cross flow. In this model, the elastic cylinder is represented by the Euler-Bernoulli beam theory, and the vortex-induced force acting on the stationary cylinder is modeled by a bounded-noise process. Fluid-structure interaction is represented by an evolution process based on the concept of quasi-steady flow. A numerical iterative approach is used to simulate the evolution process and obtain time histories of cylinder vibration and vortex-induced force. The model is validated against available measurements. It is shown that the proposed model can reproduce the salient features observed in experiments. Furthermore, quantitative agreement with experimental measurements is obtained in general. However, when the vibration amplitude is very large due to intense fluid-structure interaction, the proposed model prediction is not quite satisfactory. This suggests that the concept of quasi-steady flow is only applicable for relatively weak fluid-structure interaction.

The Numerical Simulation of Two-Degrees-of-Freedom Vortex-Induced Vibrations of Circular Cylinder with High Mass-Ratio

2013 ◽  
Vol 284-287 ◽  
pp. 557-561
Author(s):  
Jie Li Fan ◽  
Wei Ping Huang
Keyword(s):  
Circular Cylinder ◽  
Drag Force ◽  
Frequency Ratio ◽  
Lift Force ◽  
Degrees Of Freedom ◽  
Cross Flow ◽  
High Mass ◽  
Mass Ratio ◽  
Main Frequency ◽  
Line Amplitude

The two-degrees-of-freedom VIV of the circular cylinder with high mass-ratio is numerically simulated with the software ANSYS/CFX. The VIV characteristic is analyzed in the different conditions (Ur=3, 5, 6, 8, 10). When Ur is 5, 6, 8 and 10, the conclusion which is different from the cylinder with low mass-ratio can be obtained. When Ur is 3, the frequency of in-line VIV is twice of that of cross-flow VIV which is equal to the frequency ratio between drag force and lift force, and the in-line amplitude is much smaller than the cross-flow amplitude. The motion trace is the crescent. When Ur is 5 and 6, the frequency ratio between the drag force and lift force is still 2, but the main frequency of in-line VIV is mainly the same as that of cross-flow VIV and the secondary frequency of in-line VIV is equal to the frequency of the drag force. The in-line amplitude is still very small compared with the cross-flow amplitude. When Ur is up to 8 and 10, the frequency of in-line VIV is the same as the main frequency of cross-flow VIV which is close to the inherent frequency of the cylinder and is different from the frequency of drag force or lift force. But the secondary frequency of cross-flow VIV is equal to the frequency of the lift force. The amplitude ratio of the VIV between in-line and cross-flow direction is about 0.5. When Ur is 5, 6, 8 and 10, the motion trace is mainly the oval.

scholarly journals Coupling Quasi-Two-Dimensional Friction Model and Discrete Vapor Cavity Model for Simulation of Transient Cavitating Flows in Pipeline Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Qiang Sun ◽  
Yuebin Wu ◽  
Ying Xu ◽  
Liang Chen ◽  
Tae Uk Jang
Keyword(s):  
Cost Effective ◽  
Friction Model ◽  
Experimental Results ◽  
Complex Nature ◽  
Two Dimensional ◽  
Cavity Model ◽  
Cavitating Flows ◽  
Vapor Cavity ◽  
Proposed Model ◽  
Pipeline Systems

Accurate simulation of cavitating flows in pipeline systems is important for cost-effective surge protection. However, this is still a challenge due to the complex nature of the problem. This paper presents a numerical model that combines the discrete vapor cavity model (DVCM) with the quasi-two-dimensional (quasi-2D) friction model to simulate transient cavitating flows in pipeline systems. The proposed model is solved by the method of characteristics (MOC), and the performance is investigated through a numerical case study formulated based on a laboratory pipeline reported in the literature. The results obtained by the proposed model are compared with those calculated by the classic one-dimensional (1D) friction model with the DVCM and the corresponding experimental results provided by the literature, respectively. The comparison shows that the pressure peak, waveform, and phase of pressure pulsations predicted by the proposed model are closer to the experimental results than those obtained by the classic 1D model. This demonstrates that the proposed model that combines the quasi-2D friction model with the DVCM has provided a solution to more accurately simulate transient cavitating flows in pipeline systems.

HAM Solutions for Vortex-Induced Vibration of a Circular Cylinder

2014 ◽  
Author(s):  
Zhiliang Lin ◽  
Longbin Tao
Keyword(s):  
Circular Cylinder ◽  
Practical Importance ◽  
Nonlinear Problems ◽  
Van Der Pol Oscillator ◽  
Fluid Structure ◽  
Vortex Induced Vibration ◽  
Highly Nonlinear ◽  
Homotopy Analysis ◽  
Simple Linear Equation ◽  
Wake Oscillation

The vortex-induced vibration (VIV) phenomenon is result of fluid-structure interaction which occurs in many engineering fields. The study of VIV of a circular cylinder is of practical importance (such as in marine cables and flexible risers in petroleum production). In this paper, one classical phenomenological VIV model — the motion of the cylinder is modeled by a simple linear equation, and the fluctuating nature of the vortex wake oscillation is modeled by a van der Pol oscillator, is analyzed. Firstly, the homotopy analysis method (HAM), a powerful technique for highly nonlinear problems, is developed to solve the coupled fluid-structure dynamical system with the convergence of the homotopy series solutions being demonstrated. Based on the HAM solutions, some properties of the fully nonlinear classical coupled VIV model are presented. All the results proved that the proposed HAM scheme has potential to be an effective analytic technique to study the VIV problems.

scholarly journals Application of the Method of Integral Relations to the Calculation of Two-Dimensional Incompressible Turbulent Boundary Layer

1981 ◽  
Vol 48 (4) ◽  
pp. 701-706 ◽  
Author(s):  
W.-S. Yeung ◽  
R.-J. Yang
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Numerical Solutions ◽  
Experimental Results ◽  
Two Dimensional ◽  
Incompressible Turbulent Boundary Layer ◽  
Method Of Integral Relations ◽  
Integral Relations

The orthonormal version of the Method of Integral Relations (MIR) was applied to solve for a two-dimensional incompressible turbulent boundary layer. The flow was assumed to be nonseparating. Flows with favorable, unfavorable, and zero pressure gradient were considered, and comparisons made with available experimental data. In general, the method predicted very well the experimental results for flows with favorable or zero pressure gradient; for flows with unfavorable pressure gradient, it predicted the experimental data well only up to a certain distance from the initial station. This result is due to the flow not being in equilibrium beyond that distance. Finally, the scheme was shown to be efficient in obtaining numerical solutions.

On Vortex Induced Vibration in Two-Degree-of-Freedoms of Flexible Cylinders

2011 ◽  
Author(s):  
Weiping Huang ◽  
Weihong Yu
Keyword(s):  
Natural Frequency ◽  
Current Velocity ◽  
Coupling Effect ◽  
Great Influence ◽  
Cross Flow ◽  
Flexible Cylinder ◽  
Fluid Structure ◽  
Vortex Induced Vibration ◽  
Flow Vortex ◽  
Lock In

In this paper, an experimental study on the in-line and cross-flow vortex-induced vibration (VIV) of flexible cylinders is conducted. The relationship of two-degree-of-freedoms of vortex-induced vibration of flexible cylinders is also investigated. The influence of natural frequency of flexible cylinders on vortex shedding and VIV are studied through the experiment in this paper. Finally, A nonlinear model, with fluid-structure interaction, of two-degree-of-freedom VIV of flexible cylinders is proposed. It is shown that the ratio of the frequencies and amplitudes of in-line and cross flow VIV of the flexible cylinders changes with current velocity and Reynolds number. The natural frequency of flexible cylinder has great influence on the vortex-induced virbation due to the strong fluid-structure coupling effect. Under given current velocity, the natural frequency of flexible cylinder determines its forms of vibration (in circular or ‘8’ form). The ratio of the VIV frequencies is 1.0 beyond the lock in district and 2.0 within the lock in district respectively. And the ratio of the VIV amplitudes is 1.0 beyond the lock in district and 1/3 to 2/3 within the lock in district. The results from this paper indicates that in-line vibration should be considerated when calculating the vibration response and fatigue damage.

Vortex-induced vibration and galloping of a circular cylinder in presence of cross-flow thermal buoyancy

2019 ◽  
Vol 31 (11) ◽  
pp. 113603 ◽  
Author(s):  
Hemanshul Garg ◽  
Atul Kumar Soti ◽  
Rajneesh Bhardwaj
Keyword(s):  
Circular Cylinder ◽  
Cross Flow ◽  
Vortex Induced Vibration ◽  
Thermal Buoyancy

Experimental Evaluation of Pure In-Line Vortex Induced Vibration (VIVx) of Low Mass-Damping Ratio Cylinder

2016 ◽  
Author(s):  
Mohammad Mobasher Amini ◽  
Antonio Carlos Fernandes
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Damping Ratio ◽  
Cross Flow ◽  
Current Channel ◽  
Number Range ◽  
Vortex Induced Vibration ◽  
Numerical Studies ◽  
Lower Amplitude ◽  
Low Mass

Numerous experimental and numerical studies have been carried out to better understand and to improve prediction of cylinder VIV (vortex Induced Vibration) phenomenon. The behavior of cylinder due to in-line vibration (VIVx) has been neglected in the earlier studies because of its lower amplitude in comparison with cross flow vibration (VIVy). However, some researchers have studied VIVx in 2DOF along with VIVy. Recent investigations show that response amplitude of structure caused by VIVx is large enough to bring it to consideration. This study focuses on understanding the origin and prediction of VIVx amplitude exclusively in 1DOF and subcritical flow regime. The experiments were performed in current channel on bare circular cylinder with low mass-damping ratio in Reynolds number range Re = 10000 ∼ 45000.

VIV Suppression and Drag Reduction With Pivoted Control Plates on a Circular Cylinder

2008 ◽  
Author(s):  
Gustavo R. S. Assi ◽  
Peter W. Bearman
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Drag Reduction ◽  
Flow Direction ◽  
Cross Flow ◽  
Two Dimensional ◽  
Dimensional Control ◽  
Helical Strakes ◽  
Low Mass ◽  
Viv Suppression

Experiments have been carried out on two-dimensional devices fitted to a rigid length of circular cylinder to investigate the efficiency of pivoting control plates as VIV suppressors. Measurements are presented for a circular cylinder with low mass and damping which is free to respond in the cross-flow direction. It is shown how vortex-induced vibration can be practically eliminated by using free to rotate, two-dimensional control plates. Unlike helical strakes, the devices achieve VIV suppression with drag reduction. The device producing the largest drag reduction was found to have a drag coefficient equal to about 70% of that for a plain cylinder at the same Reynolds number.

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