Vortex-induced Vibration Response Research Articles

Vortex-induced vibration response of the cylinder inspired by Terebridae

Vortex-induced Vibration (VIV) responses of the three-dimensional cylinders inspired by Terebridae are numerically investigated at the Reynolds number ranges of 0.8 × 104 ≤ Re ≤ 8.0 × 104. By Terebridae, we mean that inspired by its slender structural shape, and whether it can be used to improve the VIV suppression performance of the traditional structures. Three different cylinders are considered, including the smooth cylinder (T0), the Terebridae-inspired cylinder with four-start helical ribs (T1), and the Terebridae-inspired cylinder with six-start helical ribs (T2). The VIV responses of T1 and T2 is effectively suppressed, and T1 shows better suppression performance. The results show that the maximum cross-flow amplitude ratio of T1 is reduced by 70.7 % compared with that of T0, and the maximum in-line amplitude ratio of T1 is reduced by 85.7 % compared with that of T0. Compared with the maximum mean-drag coefficient of T0, it is reduced by 44.0 % for T1. In the high Reynolds number ranges, the galloping phenomenon does not occur for T1 and T2, and the relationship between the mean-drag coefficients of T0, T1 and T2 is Cd‾ (T2) > Cd‾ (T1) > Cd‾ (T0). It is found that the changes of Q-criterion vortex structure and wake flow play an important role in the VIV response. The Q-criterion vortex of T0 is a slightly curved linear shaped, and the Q-criterion vortices of T1 and T2 are break up. The three-dimensional geometry of the Terebridae-inspired cylinder undermines the correlation of vortex-shedding along the span. The wake flow of T0 can develop normally. The wake flow of T1 quickly rolls up after passing through the top separation point, and the reattachment of the wake vortex destroys the development of the original wake flow. The continuous development of the boundary layer is destroyed by multiple Terebridae-inspired ribs of T2, resulting in the broken wake. Through the comparison of vortex force, it can be seen that the vortex force of T1 is significantly weakened compared to that of T0, and this also indicates that the three-dimensional geometry of T1 can effectively reduce the intensity of the wake flow.

Spatio-temporal distribution of aerodynamic forces and their associated vortex drift patterns around a closed-box girder during torsional vortex-induced vibration

Torsional vortex-induced vibrations (VIVs) pose potential risks to prototype bridges with increasing spans and lower damping levels. However, the underlying mechanism remains unclear. Wind tunnel tests revealed that torsional VIVs occurred at an initial attack angle of + 3°. To unravel the VIV mechanism throughout the lock-in range, encompassing the ascent stage, amplitude extremum, and descent stage, the spatio-temporal distribution of aerodynamic forces around the bridge girder was analyzed. The results demonstrated the presence of traveling pressure waves with approximately 2.5 wavelengths and three uniformly distributed separated vortices over the upper side throughout the lock-in range. The primary source of these travelling pressure waves stemmed from the vortex drift patterns, with the aerodynamic wave travelling velocity equating the vortex drift velocity. The formation of separated vortices, known as the “double-vortex model”, occurred at the windward barrier on the upper side and windward maintenance rail on the lower side. These vortices directly imposed travelling pressure waves on the girder, thereby inducing torsional VIVs. Among them, the former vortices contributed more to the VIVs than the latter. Therefore, the formation of separated vortices and their related aerodynamic waves in the windward edge with the 2nd SVM/AWM modes predominantly governed the occurrence of torsional VIVs. Furthermore, both the ratio of the wave travelling time to the vibration period and the mean value of the wave travelling velocity ratio exhibited an inverse relationship with the VIV responses. However, the actions exerted by the vortex drift patterns were proportional to the VIV responses on both the upper and lower sides. Therefore, there existed evolutionary characteristics of aerodynamic waves and their related vortex drift patterns throughout the lock-in range, which was responsible for the “lock-in” phenomena.

Establishment and application of a digital twin for vortex-induced vibration of a bridge deck section

ABSTRACT Wind tunnel tests or computational fluid dynamics (CFD) simulations of the aeroelastic model of a bridge deck section are currently used to make sure that significant vortex-induced vibration (VIV) of a long-span bridge will not occur after the bridge is put into operation. However, significant VIV still occurred in several long-span bridges in operation, indicating that the currently used wind tunnel tests and CFD simulations have some drawbacks or uncertainties. This study aims at establishing a digital twin by interacting CFD simulation with wind tunnel test for accurately and efficiently predicting the VIV response of a bridge deck. The measurement information of VIV of the deck section is collected from the wind tunnel test and fused with the CFD simulation. The optimisation for reducing uncertainties existing in wind tunnel test and CFD simulation is then carried out to make the CFD simulation as a digital twin. The digital twin is finally used to investigate the blockage effect of wind tunnel test and give an accurate and efficient prediction of VIV of the bridge deck. The flat closed-box steel deck section used in the Xiangshan Harbor cable-stayed bridge is selected as a case study. The results from the case study show that the digital twin can be established and used for an accurate and efficient prediction of VIV of the bridge deck section.

Numerical investigations of the effects of spanwise grooves on the suppression of vortex-induced vibration of a flexible cylinder

Numerical investigations of Vortex-induced Vibration (VIV) suppression of a flexible cylinder with spanwise grooves in the uniform flow have been conducted by viv3D-FOAM-SJTU solver, which imports the thick strip model into OpenFOAM. The Reynolds-averaged Navier-Stokes (RANS) method is adopted to calculate hydrodynamic forces at each fluid strip. The vibrations of cylinder are solved through the Euler-Bernoulli bending beam hypothesis and the Finite Element Method (FEM) in two directions. During simulations, four spanwise grooves are arranged equally around the cylinder with an interval of 90° at two configurations. The spanwise groove keeps a constant width of w = 0.2D and a variable groove depth among 0.08D, 0.12D and 0.16D. Specific comparisons on Root Mean Square (RMS) vibration displacements, vibration modal responses, vibration frequency responses and vortex structures are conducted to analyze suppression effects of the spanwise grooves. Numerical studies indicate that the appropriate choose of groove geometry and arrangement can effectively reduce both crossflow and inline VIV responses.

Response Characteristics and Suppression of Vortex-Induced Vibration of the Flexible Cable

To investigate the vortex-induced vibration (VIV) of a flexible cable in the uniform flow, experiments were conducted using a flexible cable with an external diameter of 80[Formula: see text]mm and a length of 10.48[Formula: see text]m in the wind tunnel. The characteristics of multi-modal VIV, time-frequency and traveling wave behavior of the flexible cable were analyzed. Moreover, the effects of twist direction, diameter and the single/double helical wire on the VIV characteristics of the flexible cable were investigated. It is found that the flexible cable experiences single and multi-modal VIVs in uniform flow at different incoming wind speeds, respectively. For the multi-modal VIV of the flexible cable, the vibration over the time history is dominated by two adjacent modal frequencies and shows a phenomenon of beat vibration. The multi-modal VIV responses of the flexible cable show a mix of standing and traveling wave behaviors, in which the effects of standing wave are more pronounced near both ends and the effects of traveling wave are more dominant in the middle region of the flexible cable. The twist direction of the helical wire has little effect on the VIV responses of the flexible cable. The VIV amplitudes of the flexible cable can be reduced by a single helical wire. With the diameter of the helical wire increases, the suppression effects of the single or double helical wire on the VIV of the flexible cable can be improved. Particularly, the double helical wire with diameter 0.10D can effectively suppress the VIV of the flexible cable.

Effects of a detached splitter on the vortex-induced vibration of a 5:1 rectangular cylinder

The present paper examines the vortex-induced vibration (VIV) of a 5:1 rectangular cylinder with a detached splitter in its near wake. The tested gap ratio between the cylinder and the splitter (g/D, where g is the gap between the cylinder rear and the splitter and D is the depth of the rectangular cylinder) ranges from 0.5 to 2.0, with an increment of 0.5. To serve as a reference case, the rectangular cylinder without the splitter is also tested under the same conditions. The test Reynolds number ranges from 32 320 to 56 507. This study delves into the vibration response, pressure distributions, and power spectral densities (PSD) of the cylinder under varying gap ratios. Based on qualitative and quantitative analyses between the cylinder and the splitter using phase average techniques, smoke-wire visualization, and numerical simulation, the different vortex shedding modes according to different gap ratios were identified. Experimental and numerical results show that the detached splitter and its gap ratio play important roles in determining the cylinder VIV properties. For g/D = 0.5, the detached splitter has a sensible mitigation on the cylinder VIV. However, as the gap ratio increases, the VIV response initially recovers to the reference case at g/D = 1.0 and subsequently enlarges at g/D = 1.5 and 2.0. The pressure distribution results showed that the detached splitter demonstrates its effects primarily through fluctuations in the pressure field rather than the mean field. In addition, at g/D = 0.5, a sensibly decayed PSD is observed, while at g/D = 1.0–2.0, an intensified PSD is detected. The underlying mechanism of the detached splitter on the VIV of the 5:1 rectangular cylinder should be attributed to the von Kármán vortex street compared to the reference case.

Study on vortex-induced vibration mitigation of parallel bridges by multi-tuned mass damper inerter

This study proposes a novel Multi-Tuned Mass Damper Inerter (MTMDI) system for mitigating the vortex-induced vibration (VIV) responses of parallel bridges. In the proposed system, two individual bridges are linked using two Tuned Mass Damper Inerters (TMDIs). A model of parallel bridges with MTMDI under vortex-induced force is constructed, and two additional schemes wherein each bridge is equipped with a TMDI and a Tuned Mass Damper (TMD) separately are considered. The VIV responses of the parallel bridges are estimated through full bridge aeroelastic model wind tunnel tests. The performance of the MTMDI system with the optimal parameters obtained by the multi-objective optimization technique is compared with the performance of the other aforementioned two schemes. The results indicate that the optimal MTMDI system with smaller attached mass and inertance effectively mitigates the vertical VIV responses when applied to the parallel bridges. The frequency response functions and displacement time histories further demonstrate the effectiveness of the MTMDI system as an attractive alternative to the other schemes. Finally, the sensitivity of performance against variations in each parameter in the MTMDI system is discussed.

Study on VIV Behavior of Two 5:1 Rectangular Cylinders in Tandem Based on Correlation Analysis

To investigate the vortex-induced vibration (VIV) characteristics of two rectangular cylinders with a width-to-depth ratio of 5:1 in a tandem arrangement, sectional model wind tunnel tests that measure vibration responses and pressure distributions simultaneously were adopted. The ratio of the spacing between the cylinders to its width is 1.2. The analyses were performed considering VIV responses as well as the distribution characteristics of mean and rms pressure coefficients. Additionally, the time-frequency domain statistical parameters like correlation and contribution coefficients, phase lags between distributed and general vortex excited forces (VEFs), and amplitudes of VEF coefficients at predominant frequencies were calculated to analyze the physical VIV mechanism of two 5:1 rectangular cylinders in tandem. This study indicates that the influence of incidence angles on the dynamic responses is notable; the contribution of the distributed VEFs acting on the trailing surface of the upstream cylinder and the leading surface of the downstream one is significant to VIVs of the cylinders from wind pressure distribution characteristics and correlation analyses.

Effect of a rotatable water-drop plate on vortex-induced vibration of cylinder

To suppress the Vortex-induced vibration (VIV) response, a cylinder with a rotatable water-drop plate is investigated. The influence of the side curves (concave, linear, convex) of the water-drop plate and angle α (α means the angle between the positive half axis of the X-axis and the straight line where the side of the water-drop plate is located, taking 15°, 30°, 45°, and 60°) on the vibration response are studied by adopting uRANS equations and Newmark-β method. It is shown that the water-drop plate has a certain suppression effect on the VIV of the cylinder in the initial and upper branches. A convex plate with a smaller angle is more effective in suppressing the vibrations of cylinders. When the angle decreases to 30°, the suppression effect of the convex plate on the cylinder no longer increases significantly even if the angle continues to be reduced. In the lower branch and desynchronization, the phenomenon of galloping is clearly observed and the amplitude of the cylinder increases continuously.

Experimental research on vortex-induced vibration suppression of pipeline intelligent plugging operation

Pipeline maintenance technology based on smart isolation device (SID) is an important method to prevent failure accidents for subsea oil and gas pipelines. However, during the plugging operation, vortex-induced vibration may occur due to the complex changes of flow field, which can affect the plugging stability. To ensure the safety of plugging operation, it is necessary to reduce the vortex-induced vibration caused by pipeline plugging. In this paper, an experimental investigation on vortex-induced vibration suppression for subsea pipeline plugging operation is conducted from three aspects. The shape of end face, plugging velocity and spoiler device are investigated to suppress the vortex-induced vibration response. The results demonstrate that the vibration suppression effect of end faces with hemispherical shape is the best compared with the footstep shape and parabolic shape. For the plugging velocity, high-velocity plugging can induce stronger water hammer phenomenon, leading to destructive vibration of pipelines. In addition, the active spoiler device with two relative spoilers achieves the best vibration suppression effect, and the average fluctuation rate has decreased by 7.6%. The experimental research can ensure the safety of plugging operation, which is beneficial for preventing pipeline failure.

Spanwise layout optimization of aerodynamic countermeasures for multi-mode vortex-induced vibration control on long-span bridges

Aerodynamic countermeasures are widely used to control vortex-induced vibration (VIV) on long-span bridges. However, due to the lack of appropriate three-dimensional (3-D) VIV analysis approach, these countermeasures are usually installed along the entire span of the bridge deck, leading to excessive costs. This study proposes an optimization method for the spanwise layout of aerodynamic countermeasures, aiming to achieve an economical control scheme for multi-mode VIV. An improved mode-by-mode 3-D VIV analysis approach is developed based on the generalized polynomial model to predict the VIV responses of the bridge with different spanwise layouts of aerodynamic countermeasures. The genetic algorithm (GA) is then employed to search for the most economical layout scheme with constraints of limited multi-mode VIV responses. Two alternative types of search spaces for the optimization are presented. The effectiveness of this optimization method is demonstrated on a long-span suspension bridge in conjunction with finite element simulation and wind tunnel tests. The results show a noteworthy reduction in the use of aerodynamic countermeasures, thus highlighting the necessity of countermeasure layout optimization.

Random vortex induced vibration response of suspended flexible cable to fluctuating wind

Random vortex induced vibration response of suspended flexible cable to fluctuating wind

An improved van der Pol wake oscillator model for a 1DOF circular cylinder undergoing vortex induced vibrations

An optimization procedure is presented for prescribing the empirical coupling parameters of a modified coupled van der Pol (VDP) wake oscillator and mass–spring–damper system for a one degree of freedom (1DOF) circular cylinder system undergoing vortex induced vibrations (VIV). This approach allows for the generalization of the traditional VDP model to cover a large VIV parameter range. The procedure is developed using experimental data covering the parameter space: 3<U∗<11, 8<m∗<20, 0.003<ζ<0.063, ReD=4000. The VDP model contains empirical coupling coefficients that describe the regime specific dynamic damping, ϵ, and wake coupling, β. Two calibration procedures are considered and the improvements over the traditional VDP model in predicting the VIV response are discussed. Subsequently, a regression fit is used to prescribe the two empirical coupling coefficients as functions of m∗, ζ and U∗. The generalized model results in a better prediction of the VIV response in terms of identification of lock-in regimes, lock-in frequency and amplitude response over several regimes when compared to the classical models. The use of a functional representation replaces the need for using tables and reduces user input for determining regime-specific coupling coefficients.

Predictions of multi-scale vortex-induced vibrations based on a multi-fidelity data assimilation method

This paper presents a data assimilation method based on the POD-DeepONet structure to fuse two types of fidelity data from vortex-induced vibration (VIV) problems. The data is mainly focused on amplitude response in different oncoming flow cases from cross-flow (CF) and inline (IL) directions for new flow speed predictions. The low-fidelity data in this paper is calculated from a semi-empirical code called DAVIV, while the high-fidelity data is measured from laboratory experiments. For a complex nonlinear correlation in amplitude and phase error between low and high-fidelity data, the POD-DeepONet structure receives better accuracy and more stable predictions than Neural Network with few training cases. It can successfully reconstruct the amplitude response along the marine riser and capture the changing trend with the oncoming flow speed. The POD-DeepONet is then applied to predict the VIV cross-flow and inline responses with different datasets. The prediction of mean square error (MSE) shows an exponential decline trend with the increasing case number for training. With the exponentially fitted MSE formula, the required case number under the expected error can be quickly obtained, which may provide a reference for efficient and high-fidelity VIV response prediction in engineering.

Experimental investigation on the nodal-shaped oscillation in vortex-induced vibration of a rectangular cylinder

This paper presents a peculiar nodal-shaped oscillation in vortex-induced vibration (VIV). This response is distinct from the commonly observed limit cycle oscillation in VIV and other aeroelastic problems. To gain insight into the dynamics in nodal-shaped oscillation, we conduct wind tunnel tests to investigate the VIV response of a freely oscillating rectangular cylinder with various transverse structural natural frequencies fs and wind speeds. The evolution of the flow field during nodal-shaped oscillation was examined using time-frequency analysis and modal analysis. During the divergent stage of the nodal-shaped oscillation, two modes, namely, the wake mode with a frequency of f = 1.28fs and the structure mode with a frequency of f = fs, were found to dominate the response of the flow. The two modes in VIV are coupled and compete with each other, diverging the oscillation of the structure. As the oscillation diverges and the amplitude increases to the maximum, the wake mode vanishes, which disengages the coupling of the fluid and structure modes. This stops the VIV and the oscillation decays until the wake mode reappears at f = 1.28fs. The above processes cycle over and over again, resulting in nodal-shaped (divergent-decay-divergent-decay) oscillation cycles. This finding explains the underlying dynamical mechanism of nodal-shaped oscillation and demonstrates the strong relationship between the wake mode and VIV.

Study on Vortex-Induced Vibration Response of Riser under the Action of Oscillating Flow Superposition

Based on the slicing method and overlapping grid method, the bidirectional and sequential coupling of the fluid domain and riser structure is realized by UDF programming. A numerical model of vortex-solid coupling is constructed to study vortex-induced vibration characteristics of risers with different velocity ratios and different oscillation frequencies under the effect of superimposed oscillating flow. With the increase of the velocity ratio, a higher order formation appeared in the transverse vibration envelope of the riser. Meanwhile, with the increase of oscillation frequency, the vertical tube vibration envelope changed from “symmetrical up and down” to “wide up and narrow down”. There is an obvious process of “establishment”, “locking” and “decay” in the transverse-flow displacement of the riser to dimensionless, and the proportion of the “locking” phase increases gradually with the flow rate ratio, changing from 0.50 to 0.62. The effect of the oscillation frequency of the superimposed flow on the proportion of the “locked” stage is not evident. When the oscillation frequency is 0.25f1, the proportion of the “locked” stage of the riser reaches 50%.

Experimental study on the influence of maintenance track position on vortex-induced vibration performance of a box girder suspension bridge

To study the influence of maintenance track on the vortex-induced vibration (VIV) performance of main girder, the VIV response and time history of surface pressure data of a section model were obtained by wind tunnel vibration and pressure measurements for a large-span steel box girder suspension bridge. The VIV performance of the main girder was tested at ±5° attack angles of various maintenance track positions, including 1, 2.5, and 5 m away from the outer edge of the girder bottom plate. The mean values, root variances and amplitude spectra of vortex-induced force and the correlation and contribution coefficients of local aerodynamic force to overall aerodynamic force were analyzed. The results show that when the maintenance track is 1 m away from the outer edge of the bottom plate, the main girder exhibits the worst VIV performance with a maximum amplitude of 0.457 m, far beyond the allowable value of the specification. The VIV performance of the main girder was greatly improved by moving the maintenance track inward. The pressure analysis indicates that the large pressure fluctuation at the front and rear parts of the upper surface is attributed to the strong VIV of the main girder. In this sense, the improved VIV performance is mainly contributed by the weakening of pressure fluctuation in these two areas and the reduced local aerodynamic force. When the distance between the maintenance track and bottom plate is adjusted to 2.5 m, a 3.5 m wind barrier with a ventilation rate of 30% effectively inhibits the VIV of the box girder. The main reason for the suppression is that the elimination of pressure fluctuation on the upper surface of the girder disturbs the correlation between local aerodynamic force and overall aerodynamic force, consequently diminishing the contribution of local aerodynamic force to the vortex-induced force.

Investigation of the combined effect of control rods and forced rotation on a cylinder

A novel structure combining the application of control rods and forced rotation on a cylinder is proposed based on the cylindrical vibration suppression, and the combined structure is numerically simulated at a low Reynolds number of 200, an attack angle of 0°–105°, and a rotation rate of 0−1. The vortex-induced vibration responses, fluid forces, and cylindrical wake evolution are analyzed, and the VIV suppression is compared and discussed. The results show that the merging of the vortex layers on the cylinder and control rods promotes cylindrical vortex shedding, causing a high amplitude cylinder response. The cylinder vibrates at a low amplitude for no vortex layer merging. Rotation causes increased directional sensitivity of the control rod to cylindrical amplitude suppression. A 98%-cylinder amplitude suppression can be achieved by combining the control rod and rotation, while only 60% can be achieved by the control rods or rotation alone, indicating that the combined structure is highly effective for amplitude suppression.

Deciphering the influence of shape on vortex-induced vibrations: Insight from diamond and equilateral triangle cylinder simulations

In this study, we present a comprehensive numerical investigation on the impact of geometric shapes on vortex-induced vibrations (VIV). We deploy the OpenFOAM computational fluid dynamics toolbox to simulate undamped transverse flow-induced vibrations in diamond and equilateral triangular cylinders, operating at a Reynolds number of 100 in a uniform flow. Both cylinders possess an identical mass ratio of 10 and operate within a reduced velocity range of 1–13. Our findings reveal a substantial shift in VIV branching behavior when transitioning from a diamond to a triangular geometry, with both cylinders exhibiting solely VIV responses. Intriguingly, the triangular cylinder does not exhibit a lock-out feature. Furthermore, the triangular cylinder showcases rich dynamical behavior, the occurrence of beating. Coinciding with this geometric transition is a surge in fluid forces and heightened flow asymmetry. While the diamond cylinder predominantly exhibits the P + S mode of vortex shedding, the triangular cylinder displays an unconventional 2P vortex arrangement, contributing to the observed asymmetry. As the geometry transitions from diamond to triangular, we note a phase alignment between the lift and transverse displacement. Remarkably, the triangular cylinder exhibits a higher energy conversion efficiency than its diamond counterpart. This research underscores the significant influence of geometry on vortex-induced vibrations, providing pivotal insight for optimizing the design and performance of structures subjected to fluid flows.

Application of nonlinear stiffness mechanism on energy harvesting from vortex-induced vibrations

This study investigates the potential of vortex-induced vibration (VIV) as a renewable energy source, achieved when fluid flow interacts with a bluff body, inducing self-sustained oscillations through vortex shedding in the wake. While VIV research has traditionally focused on understanding its mechanisms and mitigating detrimental effects, interest in VIV energy harvesting has surged as a means to convert marine hydrokinetic (MHK) energy into usable electrical power. The nonlinear effects of two linear oblique springs on VIV energy harvesting are explored using the wake oscillator model, encompassing bistable and Duffing hardening stiffness. The study examines the response and energy harvesting performance while considering the impact of undeformed spring length, structural damping, and initial conditions on VIV energy conversion. Findings show that nonlinear stiffness application in the VIV system can broaden the synchronization bandwidth or reduce the VIV initiation flow speed. Bistable stiffness may broaden the synchronization velocity range, while Duffing hardening stiffness efficiently reduces the VIV initiation speed with small energy harvesting loss. Combining both stiffness types with appropriate control strategies presents a promising approach for achieving a broad synchronization VIV bandwidth and low initiation flow speed. Key parameters, such as the nondimensional parameter defining spring system obliquity and the ratio between undeformed spring length and cylinder diameter, significantly influence VIV response and energy harvesting. Moreover, optimal structural damping is vital to maximize energy harvesting efficiency, and understanding and controlling initial conditions are crucial for optimizing VIV synchronization bandwidth and energy harvesting efficiency for both bistable and Duffing hardening stiffness. This study provides valuable insights into VIV system dynamics and energy conversion potential with nonlinear springs, offering promising avenues for enhancing energy harvesting efficiency and inspiring further applications of nonlinear effects in VIV energy converters.