Effects Of Vortex-induced Vibration Research Articles

Vortex-induced vibration effect on the aeroelastic stability of two composite cylindrical shells using a fluid-structure interaction method

The purpose of this study, is to investigate the aeroelastic stability and effect of vortices resulting from passing air over cylindrical shells in three-dimensional condition. Here, the Naiver-Stokes equations in the integral form are considered studying the air flow based on the finite-volume method. The ANSYS Fluent software is used to study the fluid-solid interaction effect. The shear stress transport (SST) turbulence model is utilized to simulate the turbulent viscosity. Effect of different parameters such as two cylindrical shells alignment or two cylinders diameter ratio are considered. The results indicate that the vortices can play a significant role on the aeroelastic stability of the cylindrical shell.

Statement of Removal

A randomly fluctuated vortex-induced vibration (VIV) affects the localization of moving targets in an underwater acoustic wireless sensor network (UAWSN) to cause an offset time and time synchronization error which disturbs the localization of the non-cooperative moving target. Definition 2.1, theorem 2.2 has been introduced in the present work to describe the genesis and consequences of the VIV effect in UAWSN. An elliptic localization introduces the direct and indirect path measurements of the moving target. The standard CRLB parameter quantifies the VIV effect. The compensation of vortex-induced vibrations (CVV) algorithm is proposed to quantify the degradation of localization performance and to estimate the position of the moving target. The theoretical measurements of position error, velocity error with respect to the variation of noise, number of receiver sensors, and probability of line of sight (LOS) errors are compared to the standard methods. The proposed CVV algorithm improves the localization performance by 32.24% and reduces 34.36% of position errors, and 37.46% of velocity errors up to 600 meters. It can be useful for the sub-aquatic internet of underwater things.

Efficiently harvesting low-speed wind energy by a novel bi-stable piezoelectric energy harvester from vortex-induced vibration and galloping

Designing low-cost and simple harvesters to convert natural wind energy into electricity is regarded as a promising method to realize the self-powering of node sensors in the Internet of Things. However, the inherent challenge lies in the typically low and fluctuating speeds of environmental wind, making efficient energy harvesting a difficult task. To address this challenge, this study introduces a novel bi-stable wind energy harvester designed to undergo inter-well oscillations through the synergistic effects of vortex-induced vibration and galloping. The bi-stability is achieved by incorporating three magnets. To enhance the extraction of energy from low-speed wind, a square-sectioned bluff body is affixed to the cantilever beam's tip, accompanied by two foam balls. Simulations elucidate the fluid dynamics around the bluff body and foam balls, revealing that the induced vortex causes swinging in the balls, subsequently driving the piezoelectric beam to oscillate and jump. The study establishes the potential energy and force–displacement relationship of the proposed harvester to provide insights into the flow fields. A physical prototype of the harvester is fabricated and subjected to verification experiments in a wind tunnel. Results indicate that the proposed harvester exhibits snap-through or inter-well oscillations, generating a desirable energy output at wind speeds exceeding 1.3 m/s. Notably, even at very low wind speeds, the proposed harvester, despite exhibiting the same intra-well motion as its linear counterpart, achieves significantly higher output voltage due to magnetic interaction and bi-stability. Demonstrating superior performance with a voltage output of up to 10.5 V at a wind speed of 1.6 m/s, compared to the mere 0.7 V from its linear counterpart, the proposed harvester shows the advantages of bi-stability and snap-through motion in low-speed wind energy harvesting.

Vortex‐induced vibration effects in underwater acoustic wireless sensor networks

AbstractA randomly fluctuated vortex‐induced vibration (VIV) affects the localization of moving targets in an underwater acoustic wireless sensor network (UAWSN) to cause an offset time and time synchronization error which disturbs the localization of the non‐cooperative moving target. Definition 1, Theorem 1 has been introduced in the present work to describe the genesis and consequences of the VIV effect in UAWSN. An elliptic localization introduces the direct and indirect path measurements of the moving target. The standard Crammer Rao lower bound parameter quantifies the VIV effect. The compensation of vortex‐induced vibrations (CVV) algorithm is proposed to quantify the degradation of localization performance and to estimate the position of the moving target. The theoretical measurements of position error, velocity error with respect to the variation of noise, number of receiver sensors, and probability of line of sight errors are compared to the standard methods. The proposed CVV algorithm improves the localization performance by 32.24% and reduces 34.36% of position errors, and 37.46% of velocity errors up to 600 m. It can be useful for the sub‐aquatic internet of underwater things.

Effect of vortex-induced vibrations on mass transfer enhancement in a channel with two cylinders in tandem arrangement

The vortex-shedding phenomenon leads to a self-sustained vibration named Vortex-Induced Vibration (VIV), an important mass transfer enhancement method. This work studies the VIV effects of two circular cylinders inside a channel in a tandem arrangement on the mixing performance. A comprehensive study is conducted on different modes of cylinder vibrations, i.e., both cylinders vibrate, one cylinder vibrates, another cylinder is stationary, and both cylinders are stationary. The finite volume method is applied to solve the fluid flow equations, and the cylinders' vibration is modeled as a mass-spring-damping system. At low ranges of the reduced velocity, the vibration's amplitude of the cylinder is significant, and the mixing index reaches its highest values. For the case in which the distance between two cylinders is four times their diameter, the best mixing performance is related to two vibrating cylinders. In this mode, the mixing index increased up to 35% and 78% with respect to two stationary cylinders and a single stationary cylinder, respectively. Also, the investigation shows that increasing the distance between the cylinders improves the mixing process. For cylinders' distances of 4.5 and 5, the mixing index reaches 98% and up at the channel outlet.

Improving the aerodynamic performance of Trans-Tokyo Bay Bridge using reliability-based design optimization

ABSTRACT The Vortex-Induced Vibration (VIV) phenomenon can cause fatigue damage. Usually, countermeasures are implemented to mitigate the VIV amplitudes. However, its cost is high. Therefore, approaches have been developed to avoid VIV at an early stage of design. Most such studies have focused on avoiding the coincidence of the vortex shedding frequency with the natural frequency of the structure and delaying VIVs by including geometrical changes to the leading and trailing edges in order to divide the oncoming flow. In this study, a new framework is proposed to find the optimal deck cross-sectional shape of Trans-Tokyo Bay Bridge, based on Reliability-Based Design Optimization (RBDO) and aiming to mitigate the VIV effects under uncertainty. Validation of the optimal designs is conducted via Computational Fluid Dynamics (CFD) simulations for different target reliability indices.

Coupling effect of vortex-induced vibration and local scour of double tandem pipelines in steady current

Submarine pipelines are critical for offshore oil and gas production. However, when these pipelines are located on the seabed, they are susceptible to simultaneous occurrences of local scour and vortex-induced vibration, which impose a significant threat to pipeline safety and integrity. To address this issue, our study investigates the coupling effect of vortex-induced vibration and local scour using Flow-3D. Specifically, we explore the influence of the gap ratio on the vibration and local scour of the pipelines. Our findings reveal that the horizontal gap between the pipelines significantly affects the depth and profile of the scour pits. When the horizontal gap ratio is G/D = 2, pipeline vibrations promote the merging of scour pits. And as the interference effect between the two pipelines weakens with the increase of horizontal gap, the depth difference of scour pits below the fixed and vibrating double pipelines gradually decreases. Moreover, when G/D ≥ 3, the vortices falling off the upstream and downstream pipelines are discharged separately. This results in weak interference between the pipelines and the formation of two independent scour pits.

Performance enhancement of the wavy cylinder-based piezoelectric wind energy harvester with different wave-shaped attachments

The vortex-induced vibration (VIV)-based piezoelectric wind energy harvester (PWEH) has a small working bandwidth and poor wind energy harvesting performance. In order to improve the output power of the PWEH and achieve sustainable power supply for microelectronic products, this study proposes a novel wavy cylinder-based PWEH with two wavy attachment rods attached to the surface of the wavy cylinder, the mathematical model of PWEH is developed. The flow-induced vibration (FIV) response mechanism and the energy harvesting characteristics of the wavy cylinder-based PWEH are numerically explored. The wavy cylinder with wavy-shaped attachments produces a three-dimensional shear layer that can increase the wavy cylinder’s aeroelastic instability range and realize the synergistic effects of VIV and galloping, which increases the wave cylinder’s vibrational amplitude and lowers the galloping critical wind speed. Compared with the typical VIV-PWEH, the novel wind energy harvester can work outside the VIV lock-in range, and its output power and voltage rise as wind speed does. The wavy attachment rods with triangular cross section have greater advantages than other rods, its output power is 6.13 mW at a wind speed of 5.7 m/s and load resistance of 100 KΩ, compared with the circular cylinder PWEH, the average power increases by approximately 166%. The study’s findings can theoretically promote the enhancement of PWEH’s energy harvesting efficiency.

Vortex-induced vibration effect of extreme sea states over the structural dynamics of a scaled monopile offshore wind turbine

In order to demonstrate the relevance of considering Vortex-Induced Vibrations (VIV) in the structural design of marine structures, this study proposes an alternative experimental and analytical approach in wet conditions to measure the fluid–structure interaction in the near field and quantify the viscous damping with measured structural and 3D hydrodynamic accelerations. It was demonstrated that VIV caused and incremented 5.00% of the structural damping coefficient, and the extreme wind loading increased 74% of the offshore monopile’s structural damping, demonstrating the relevance of the high non-linear hydrodynamics effects during selecting parameters into the structural design in offshore applications.

Vortex-induced vibration effects on mixing performance

The effect of vortex-induced vibration (VIV) of an elastically mounted rigid circular cylinder with two degrees of freedom movement on the mixing process in a straight channel micromixer is studied. The main objective is to investigate the effect of the reduced velocity ranging from 2 to 16 and the Peclet number in the range of 200–800 on the mixing index, pressure drop, mixing performance, streamwise and transverse displacements and oscillations frequencies. The mass-spring-damper system is utilized in order to model the cylinder vibration. The results indicate that the VIV improves the mixing efficiency significantly at low reduced velocities. In addition, the positive effect of VIV on mixing performance is greater at high Peclet numbers. In comparison with the stationary cylinder, at the reduced velocities of 2.5 and 4.5, an amazing improvement of 82.7% in the mixing index and 24% in the mixing performance is observed, respectively.

Fatigue Analysis of the Oil Offloading Lines in FPSO System under Wave and Current Loads

In this paper, fatigue analysis of oil offloading lines (OOLs) in the floating production storage and offloading (FPSO) catenary anchor leg mooring (CALM) buoy offloading system under wave and current loads in the West Africa Sea area is carried out by the numerical simulation method. The hydrodynamic coupling response is calculated, and fatigue damage is analyzed. Firstly, the numerical model is verified by comparison with the experimental results. Then, according to the environmental statistics in West Africa, the influence of various parameters on the fatigue damage of OOLs is analyzed, including tension characteristics, wave parameters, and structural parameters. Additionally, the effect of current load is studied. Results show that accumulated fatigue damage mainly occurs near the CALM buoy and is mainly caused by the 0° wind wave. Appropriately reducing the cover length of buoyancy material and increasing the wall thickness can reduce fatigue damage. Moreover, the effect of the shuttle tanker can increase the fatigue damage of the OOL near the CALM buoy by about 1.5 times, and the effect of vortex-induced vibration can increase the fatigue damage of the OOL in the middle part by up to 5–10 times.

An investigation on vortex-induced vibration of a flexible riser transporting severe slugging

An investigation on the dynamic characteristics of a flexible riser due to the coupling effects of Vortex-Induced Vibration (VIV) and severe slugging is performed in this paper. Firstly, a 2D Computational Fluid Dynamics (CFD) model is developed for capturing the dynamic characteristics of severe slugging. Based on the mass and velocity of internal fluid from the CFD analysis, a classical van der Pol oscillator is employed to simulate the dynamic characteristics of the effect of VIV coupled with severe slugging. The governing equation of the riser with internal flow is discretized by the finite difference method and it is then solved by the Runge-Kutta method. The results show that the effect of severe slugging exhibits quite distinguished dynamics owing to the intermittent feature both in in-line (IL) and cross-flow (CF) directions. The VIV characteristics of the riser with severe slugging, such as frequencies, dominant modes, and root mean square (RMS) displacements, are substantially different from those of the riser without internal flow. In addition, severe slugging may trigger new mode responses of the riser and a multi-frequency vibration phenomenon in IL and CF directions due to severe slugging is observed.

Nonlinear modeling and efficacy of VIV-based energy harvesters: Monostable and bistable designs

In this effort, performance of a magnetoelastic multi-stability energy harvester is investigated in monostable and bistable configurations while working under combination of vortex-induced vibration (VIV) and base excitation. For this purpose, a mathematical model is developed that accounts for coupled lift force, magnetic force, cylinder’s motion, and generated voltage. First, a linear analysis is carried out to investigate the effects of electrical load resistance on the coupled natural frequency of the system and its impact on the synchronization region. Static and frequency analyses are performed to identify the point of buckling based on the distance between the magnets. Then, a reduced-order model based on the Galerkin discretization is derived to investigate the effects of various nonlinearities on the harvester’s response. A convergence analysis is examined up till seven modes and it is found that three modes are sufficient. To compare the efficacy of the energy harvester at same coupled frequency in monostable and bistable regimes, three pairs of datasets are selected. Various parametric studies are presented to investigate the impacts of distance between the magnets, electrical load resistance, frequency, and wind speed. This study not only presents one of its kind quantitative comparisons of performance of the energy harvester working in monostable and bistable regimes at same coupled frequency but also provides an insight to performance of the harvester under combined effect of VIV and base excitation. In this regard, quenching phenomenon is visible. In addition, performance trends in pre-synchronization region, synchronization region, hysteresis region, and post synchronization regions are explained by presenting four wind speed graphs together. Some phase portraits and time histories are included for further exploration. In nutshell, the study is very useful for understanding of monostable and bistable designs and their working under VIV as well as hybrid excitations.

Numerical investigation of vortex induced vibration effects on the heat transfer for various aspect ratios ellipse cylinder

The vortex-induced vibration of various aspect ratio (AR=0.75, 1.0, 1.25 and 1.5) ellipse cylinders with convective heat transfer is investigated at Re=150 and m∗=10 for 3≤Ur≤12, where Ur=U/(fnD) and fn is the natural frequency of cylinder in still air. The amplitude and frequency response of displacement, force and the Nusselt number are presented and discussed, the vorticity, temperature contours and wake patterns are studied to understand the effect of AR and Ur on the 1DOF vibration characteristics and the heat transfer of the isothermal cylinder. The results show that the classical Karman shedding (2S) is observed at relative low displacement and the C(2S) occurs when the cylinder undergoes high-amplitude oscillations for the AR considered, and the P+S wake mode which is composed with a single vortex and one pair of counter-rotating vortices during the transition from the initial branch to the VIV lock-in regime. There are multiple frequencies related to the response of Nusselt number, with the 2StNu dominating. And the maximum value of NuA is 11.07, 11.7, 12.1 and 12.35 for AR=0.75, 1.0, 1.25 and 1.5 respectively, which are increased by 7%, 8.7%, 11% and 13.5%, respectively, compared with the corresponding stationary cylinders, indicting an enhanced heat transfer of VIV cylinder. As increasing of the AR to 1.5, an early exit of the VIV lock-in regime and into the desynchronized regime happens due to the strong 2Stn in the lift frequency response when.

Nonlinear riser-seabed interaction response among touchdown zone of a steel catenary riser in consideration of vortex-induced vibration

Steel catenary riser (SCR) is a preferred solution for deepwater oil and gas exploitation under harsh marine environment. Its riser-seabed interaction (RSI) among touchdown zone (TDZ) in consideration of the vortex-induced vibration (VIV) of sag bend is at present a research frontier in ocean engineering. This paper integrates Randolph-Quiggin model into a published global numerical riser model, to investigate the nonlinear RSI response among TDZ of an SCR with VIV. The adopted numerical model is validated against some published experimental measurements for VIV and RSI respectively. Three combined cases with top-end platform heave motion and VIV are simulated, and the trench development as well as the SCR's response characteristics among TDZ is analyzed. VIV makes the trench develop more smoothly, and the trench length as well as depth turns smaller. The VIV effect on RSI is relatively significant with violent heave excitation, under which the P-z curves present clearer interaction mode transitions. VIV enlarges the maximum bending moment visibly, and makes the sag bend of SCR dominated by higher-order modes, which are both detrimental to the structural safety. The coupling effect between RSI and VIV on the riser's dynamic response needs to be considered for the design of full-scale SCRs.

Fluid-Structure interaction framework based on structured RANS solver

A Fluid Structure Interaction framework developed at CIRA to deal with multi-physics problems in a partitioned approach is presented. The CIRA multi-block structured flow solver for unsteady Navier-Stokes equations UZEN was updated and tightly coupled with an open-source solver for non-linear structural dynamics in a modular approach. The solvers are glued in space and time through an open source library, able to control the executing processes and to deliver exchanging data by specific adapters. The validity of the framework is tested on vortex-induced vibration effects of a cantilevered beam in low Reynolds flow and on as three-dimensional wing flutter in transonic turbulent flow.

Slug flow's intermittent feature affects VIV responses of flexible marine risers

Slug flow is characterized by the variations of internal flow parameters with time and position. This study aims to investigate the slug flow effect (SFE) on the cross-flow Vortex-Induced Vibration (VIV) of a flexible riser. A steady slug-flow model is adopted using several assumptions and empirical correlations. A distribution of van der Pol oscillators is employed to create the VIV effect. A novel approach has been proposed to capture the intermittent feature which is validated by comparisons with experiments. The SFE is explored by comparisons of the dynamic behaviors of a flexible riser subject to two uniform currents, assuming the pipe is filled with still liquid, transporting a single-phase liquid flow and a two-phase slug flow. It has demonstrated that the SFE is much more profound than the single-phase internal flow effect. A flexible riser conveying a slug flow can exhibit quite distinguished dynamics owing to the intermittent feature. Apart from triggering new modes, the combination of slug flow frequency and VIV frequency can generate an amplitude-modulation phenomenon of excited modes. Most distinctively, beating behaviours which corresponds to the resonant synchronization have been captured. This study can contribute to fatigue analysis of a flexible riser conveying a two-phase slug flow.

Performance evaluation of inerter‐based dampers for vortex‐induced vibration control of long‐span bridges: A comparative study

Inerter-based dampers (IBDs) have been proposed to enhance the efficiency of conventional tuned mass dampers (TMDs) in controlling wind-induced vibration of civil structures recently. In this paper, four different IBDs, with each featuring a specific combination of dashpot–spring elements in series or in parallel with the inerter device, are applied to control the vortex-induced vibration (VIV) of long-span bridges. The governing equations of the bridge–IBD system under the effect of VIV are established, and the strategy to optimize the IBD parameters is proposed. The performances of different IBDs in terms of mitigating the VIV response of the deck, the stroke of mass block, the static deformation of spring due to gravity, the reaction force of IBDs on the bridge deck, and the robustness of the system (the control efficiency against the deviation of design parameters from their optimal values) are systematically evaluated and compared. Through this comparative study, the superiorities of IBDs to conventional TMDs in bridge VIV control are illustrated, and two feasible layouts of IBDs that are suitable for bridge VIV control are suggested. On the basis of these results, the guideline for VIV-resistance design of long-span bridges with the help of IBDs is also proposed.

Suppression of Vortex-Induced Vibration by Fairings on Marine Risers

Vortex-induced vibration is quite common during the operation of offshore risers or umbilical cables, commonly leading to serious damage to risers and reduced service life. Vortex-induced vibration of the offshore risers could be effectively suppressed by fairing devices. In this paper, a newly developed vortex-induced vibration fairing and large eddy simulation model of the FLUENT software were used for numerical analysis, experimental research and stimulating vortex-induced vibration at 0.1–2 m s –1 . The data of the numerical model with fairing was compared and analyzed to study the vortex shedding frequency at different Reynolds numbers and changes in drag and lift coefficients. The displacement state of 12 in risers with and without fairing was experimentally tested using a five degree-of-freedom balance. The vortex-induced vibration effect of the fairing was tested at different velocities. The result shows the drag reduction effect of the fairing is more obvious when the flow velocity is 0.4–1.2 m s –1 and the maximum drag reduction reaches 55.6% when the flow velocity is 0.6 m s –1 . Additionally, the drag reduction effect was obvious when the flow velocity was greater than 1.3 m s –1 and less than 0.3. The result indicates that the developed 12 in fairing, with good potential in engineering applications, has good vortex-induced vibration-suppression effects.

Prediction analysis of vortex-induced vibration of long-span suspension bridge based on monitoring data

Vortex-induced vibration (VIV) is a kind of wind-induced vibration that occurs at low wind speeds. The actual effect of VIV in bridges is different from that in wind tunnels and has a severe impact on traffic safety. Therefore, to guide the bridge management department in taking reasonable control measures in the initial stage of VIV and ensure that vehicles pass over the bridge safely, an identification model for VIV is established based on a large amount of data collected from Zhoushan Sea Crossing Bridge. Firstly, the wind field and vibration characteristic parameters of VIV are calculated based on data measured from 2014 to 2016 by anemometers and acceleration sensors. Then, by the big-data significant differences method and distribution function fitting analysis, two wind field parameters and two vibration response parameters are determined to serve as indexes in the identification of VIV. Finally, based on a parameter optimization algorithm, the VIV identification model is established and the data of 2017 are used to test the prediction model. The results show that the recognition rate of VIV is 89% and the identification model can be used to warn about the occurrence of VIV in practical engineering.