Vortex-induced Vibration Suppression Research Articles

Experimental study of wind-field characteristics and torsional vortex-induced vibrations for a split three-box deck sitting above water waves

The wind-field characteristics of a split three-box deck sitting above water waves and its torsional vortex-induced vibrations (VIVs) were experimentally investigated using wind-tunnel and wave-flume tests. The wind field was measured using turbulent flow instrumentation (TFI) Cobra probe. To test the VIVs of the split three-box deck, a test system that could elastically suspend the deck sectional model by eight springs and guarantee free oscillation of the deck sectional model only in the heaving and torsional directions was constructed. The test results indicated that the regular wave height (H) and regular wave period (T) mainly promoted the overall turbulence-intensity (Iuvw) and turbulence-intensity component (Iw). These contributions were further strengthened by an increase in H and a decrease in T, respectively. In general, the variations in Iuvw and Iw, particularly the latter, should be regarded as the major cause of the change in the maximum torsional VIV amplitudes of the deck sectional model with a scale ratio of 1:60 when compared to the mean local wind speed (U) and wind-speed component (w). The differences in these amplitudes under different cases in the first lock-in regions were not evident, whereas those in the second lock-in regions were significant. In the second regions, the smaller the relative bridge clearance (a/H), the smaller the maximum torsional VIV amplitudes, and the maximum torsional VIV amplitudes increased with T, which were all smaller than those in the corresponding wind-only case. Moreover, the larger the bridge clearance (a), the larger the maximum torsional VIV amplitudes in the wind-only cases (a = 0.30, 0.42, 0.50, and 0.58 m). Evidently, the presence of water waves is conducive to the suppression of torsional VIVs of the split three-box deck when VIVs occur.

Elimination of lock-in phenomenon in vortex-induced vibration by passive modal control

Theoretical analysis and numerical results have shown that frequency lock-in in vortex-induced vibration (VIV) is caused by the instability of the structural mode rather than a resonant response to external excitations. However, there is a lack of experimental evidence supporting relevant theoretical research findings. This study investigates VIV suppression with a passive modal controller (PMC) for a circular cylinder at Reynolds numbers $Re = 60$ and $Re = 40$ , using experiments to distinguish the effects of stable and unstable wake modes. Comparative analysis before and after the implementation of the PMC reveals significant reduction in the vibration amplitude and the disappearance of the lock-in phenomenon at $Re = 60$ . The vibration frequency closely follows the vortex shedding frequency after control, while dynamic mode decomposition of the flow field indicates that the wake mode is dominant. For $Re = 40$ , the vibration is eliminated and the flow becomes steady. Additionally, the root loci of the coupled system are investigated before and after the PMC implementation via linear stability analysis. The results indicate that the PMC can alter the dynamic characteristics of the original system, causing the structural mode and PMC mode to couple when approaching the PMC frequency. Then, the interaction typically improves the stability of the structural mode. Finally, a parametric study is conducted in the experiment, as well as a linear stability analysis. The study provides experimental evidence that stability control of the structural mode is the key to suppressing VIV and eliminating the lock-in phenomenon.

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.

Laboratory measurements on the suppression of vortex-induced vibrations and rotation in long-span riserless drill strings

Riserless drilling is a leading offshore technology, but the absence of a riser causes significant vibration during outflow and rotation. However, effective methods for addressing vortex-induced vibration coupling rotation are inadequate. Experiments were conducted on riserless drill strings, and the dynamic responses were analyzed by modal decomposition theory. Results indicate that structures with higher helix numbers and screw heights exit or delay entry to the lock-in region. Triple-helix designs with screw heights of 0.2 Diameter (D) and 0.25D achieve up to 93% suppression efficiency. Increasing helix number and screw height reduces rotating drill string frequencies and delays the occurrence of the dominant frequency jump phenomenon, resulting in enhanced suppression effects. Amplitude suppression primarily occurs in medium and weak regions, while helical strakes significantly reduce amplitudes in lock-in regions. For controlling vibration and minimizing fatigue damage in rotating drill strings, it is recommended to use triple-helix structures with lower screw heights.

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.

Suppression of vortex-induced vibrations of a cylinder in inertial-elastic flow

We study Vortex-Induced Vibration (VIV) of a one-degree-of-freedom cylinder placed in inertial-elastic flows experimentally. We show that there is a critical Reynolds number for the onset of VIV in these flows and this critical Reynolds number increases when the elasticity in the fluid is increased. We also show that at a constant Reynolds number, adding elasticity to the fluid reduces the amplitude of oscillations and eventually suppresses VIV entirely. For the cases where VIV is observed, the onset of the lock-in range does not depend on the Reynolds number, as a result of the competing effects of shear-thinning and elasticity. The vortices that are observed in the wake are significantly different from those observed in Newtonian VIV: the vortices are S-shaped with relatively long tails that influence the formation of the vortices that are formed in the following cycle.

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.

Simultaneous energy utilization and vibration suppression study of a rolling-structured triboelectric nanogenerator for the vortex-induced vibration of a cylinder

Vortex-induced vibration (VIV) is a prevalent phenomenon observed in marine submersible buoys subjected to ocean currents, significantly compromising the structural fatigue life and sensor stability. Meanwhile, the provision of in-situ energy supply and long-term sustainability pose significant challenges for marine submersible buoys. To tackle these issues, this paper presents a novel approach that entails the simultaneous utilization of VIV energy and suppression of VIV through the implementation of a rolling-structured, freestanding triboelectric-layer-based nano-generator (RF-TENG). An experimental investigation has been conducted to explore the power generation mechanism of RF-TENG when subjected to VIV excitation, as well as the vibration suppression effect of RF-TENG on VIV. The following conclusions have been drawn: (1) The maximum power generation is observed within the filling rate range of 50%–60%, where the conversion of kinetic energy to electrical energy resulting from particle friction prevails. Correspondingly, the maximum vibration suppression rate is achieved within the filling rate range of 60%–90%, primarily attributed to energy dissipation due to particle collisions. Notably, at approximately 60%–70% filling rate, RF-TENG exhibits a relatively efficient and balanced performance in terms of both energy utilization and vibration suppression. (2) Particle motion irregularity is a prominent factor that greatly influences the power conversion efficiency, which is manifested as the presence of the third harmonic component in the output voltage and current. The power conversion efficiency of RF-TENG attains its peak value at a filling rate of 50%. (3) Within a certain range, an increase in particle diameter contributes to enhancing the robustness and VIV suppression efficiency of RF-TENG. However, it comes at the cost of reduced power generation capacity. In this study, under the excitation of VIV experienced by a cylinder with an effective amplitude of approximately 1.56 cm and a frequency of approximately 1.62 Hz, RF-TENG achieves a power generation density of 80 mW/m3 and a VIV amplitude suppression rate of 24%. These results suggest that RF-TENG is an effective method for synchronously collecting energy and suppressing VIV in marine structures.

Suppression of vortex-induced vibration of an elastically mounted sphere by electromagnetic force

In this paper, electromagnetic force on two degrees of freedom vortex-induced vibration (VIV) of an elastically mounted sphere for vibration suppression is numerically achieved at Re = 300. The relations between the wake structures, velocity and pressure distributions, force coefficients, and sphere displacement are investigated by varying the interaction parameter (N) of electromagnetic force. With the increase in N, the momentum of the fluid near the sphere is enhanced to control the flow separation. Therefore, both the rotation radii of the rear stagnation point (RSP) and the separation line (SL) decrease, causing the spiral vortices to become thinner. This leads to a reduction in the fluctuation amplitude of the lift coefficient and mitigates the VIV. As N exceeds 0.5, the periodic spiral vortices transform into a steady double-thread wake due to the stopping of RSP and SL rotation. Therefore, a constant lift is generated in the z-direction due to the asymmetric flow field in the x–z plane, which is accompanied by the VIV fully suppressed. Moreover, the effect of electromagnetic locations (θm) on vibration suppression is examined. With the increase of θm, the vibration suppression efficiency increases first and then decreases, which achieves the maximum vibration suppression efficiency at θm = 125°. The reason is that the electromagnetic force covers the location of the half-circle-shaped SL, which has a significant effect on the control of the flow separation.

Reduction in drag and vortex-induced vibration of a circular cylinder covered by a porous layer in the laminar regime

The reduction in drag and vortex-induced vibration (VIV) of a circular cylinder covered by a porous layer is numerically studied in the laminar regime. The mass ratio and damping ratio of the system are fixed at mr = 2 and ξ = 0.01, respectively. The effects of the Darcy number (Da = 10−4, 10−3 and 10−2), the relative layer thickness (b = 0.25, 0.5 and 1), the Reynolds number (Re = 100, 150 and 200), and reduced velocity (2 ≤ Ur ≤ 10) on the vortex shedding pattern, vibration amplitude, and dynamic forces on the system are investigated. Both the one and two degrees of freedom of motion are considered. Results show that the porous layer with Da = 10−2 is effective in drag reduction and VIV suppression for various Reynolds numbers. A porous layer with Da = 10−3 could also suppress VIV while enlarging the drag force on the system.

Numerical investigation on VIV of a circular cylinder with multiple small control rods

This study conducts a numerical simulation of the two-degree-of-freedom vortex-induced vibration (VIV) for a circular cylinder attached to multiple small control rods. It systematically investigates the effects of control rod number n, attack angle α, and gap ratio G/D on the vibration responses of the main cylinder. The control rod arrangements are classified into symmetric and asymmetric configurations based on the attack angle variation. The 5, 7, and 9 small control rods present similar impacts on the VIV's characteristics of the circular cylinder. The VIV of the main cylinder is significantly suppressed by the odd number of small control rods in two regions. The 1st excellent VIV suppression (EVS) region locates in the gap ratio of G/D=(0.2, 0.3) for all attack angles. The 2nd EVS region is within a wide range of gap ratios at the 2nd symmetric configuration. The nine control rods at G/D = 1.4–1.5 in the 2nd EVS region can completely suppress the circular cylinder VIV. Meanwhile, the flow structure of the cylinder group is fully symmetric, and vortex shedding cannot be formed behind any circular cylinders.

2D Structural Design and Numerical Simulation of a New Type of Fairing

Based on the existing fairing, the 2D structure of the fairing is improved. Through the numerical simulation of the shape and height of the spoiler structure of the fairing, and the analysis and comparison of the obtained data, the fairing structure with good vortex-induced vibration suppression is designed. The results show that H = 6.5 mm’s semicircular spoiler structure with 45° tail-angle fairing on the middle line of the side has a good effect on suppressing vortex vibration.

Numerical investigation of cylinder vortex-induced vibration with downstream plate for vibration suppression and energy harvesting

The effect of the downstream plate on the vortex-induced vibration (VIV) of the cylinder is numerically studied for the first time by using the fluid-structure interaction method. The influences of the plate height (H) and the gap length (G) between the plate and the cylinder on the cylinder dynamic characteristics are investigated. The main conclusions can be summarized as follows: (1) Cylinder will first be converted from VIV to galloping and then reverted to the classical VIV response with the increasing gap length and the plate height. (2) Under the plate interference, the switch of the wake vortex shedding mode from “2S” to “P + S″, the increase in lift odd harmonic components and amplitude, and the decrease of the phase difference between lift and displacement are the essential reasons for the enhanced vibration. (3) In the optimal galloping state (G = 0.5 D, H = 0.5 D), the cylinder amplitude and lock-in range are increased by 670.8% and 473% compared to that of the isolated cylinder system, respectively, which is beneficial to energy harvesting. (4) The reattachment flow appearance and cylinder wake vortex-shedding suppression induced by the high plate, are the deep reasons for the vibration weakening. In this case, the lift force and vortex-shedding frequency are greatly reduced, while the lock-in interval is delayed or even eliminated. (5) When H = 3.0 D and G = 0.5 D, the lock-in interval is 100% cleared, and the vibration intensity of the cylinder is reduced by 84.4%. (6) The feasibility of utilizing the square plate for flow-induced vibration control of non-cylindrical bluff bodies is verified for the first time. Overall, the above results are of great significance for optimizing structural vibration control and vortex sensing technology based on VIV suppression, as well as energy harvesting aiming at enhancing vibration.

Experiment study on vortex-induced vibration of a twin-box girder with large cantilever plates

Due to their good aerodynamic stability performance, twin-box girders are frequently adopted in long-span cable-supported bridges. However, they are also susceptible to vortex-induced vibration (VIV) since the central slot changes the flow patterns around a bridge girder. In this paper, the VIV performance of a twin-box girder with large cantilever plates was investigated through wind tunnel tests of sectional models with 1:75 and 1:30 scale ratios. Furthermore, the effects of increasing the damping ratio and installing various conventional aerodynamic countermeasures such as guide vanes, grid plates, and central stabilizers on VIV suppression of the twin-box girder were investigated. A new type of aerodynamic countermeasure named the L-shaped windshield was proposed to suppress the VIV response of the twin-box girder to an acceptable level. The results indicated that significant vertical VIV occurred for the twin-box girder, and increasing the damping ratio and installing conventional aerodynamic countermeasures could not suppress the VIV response of the twin-box girder effectively. The attachments obviously worsened the vertical VIV performance of the twin-box girder, and the attachments on the upper surface showed a more significant effect. It was further demonstrated that the L-shaped windshield is an effective countermeasure that can completely suppress the vertical VIV of the twin-box girder by greatly reducing the motion-induced vortexes in the central slot with the help of low turbulence in the turbulent flow field.

Vortex shedding characteristics and hydrodynamic forces of stationary and elastically mounted side-by-side cylinders fitted with small diameter control rods

Vortex shedding behind bluff bodies can induce noise and vibration problems when it engages in a feedback cycle of oscillations with an acoustic or structural mode. Therefore, several passive and active flow control techniques have been developed to suppress vortex shedding behind a single bluff body. However, less attention was given to the case of multiple bluff bodies in cross-flow. Therefore, in this paper, a numerical investigation is performed to study the effect of adding small diameter control rods in the vicinity of two side-by-side cylinders on the vortex shedding characteristics, the hydrodynamic fluid forces, as well as the suppression of vortex-induced vibration. The simulations are conducted at a Reynolds number of Re = 200 and the side-by-side cylinders have a spacing ratio of T∗=2.5. The number of control rods and their angular positions around the main cylinders are varied. Fitting the side-by-side cylinders with control rods has resulted in three different flow regimes compared to the base case with no control rods. These flow regimes depend on the angular positions of the control rods and they are classified as; bistable flow, stable biased flow, and merged wake flow regimes. The stable biased flow regime has resulted in the maximum reduction of the fluctuating lift coefficient of the side-by-side cylinders, especially when the control rods are placed at θ=135° from the flow stagnation point. Increasing the number of control rods around the cylinders has further reduced the fluctuating lift coefficient and produced a more symmetric wake at the rod angles which produce the stable biased flow, and the merged wake flow regimes. The vortex-induced vibration of the side-by-side cylinders is investigated when the control rods are placed at the angular position that results in a stable biased flow regime. It is revealed that fitting the cylinders with control rods at an angular position of θ=135° has resulted in reducing the vibration amplitude over the whole range of the simulated reduced flow velocities, which makes this technique a viable one to control the vortex shedding and the vortex-induced vibration of side-by-side cylinders.

Vortex induced coupled vibration of an elastically mounted square cylinder with a detached solid and flexible plate

The vortex induced coupled vibration of an elastically mounted square cylinder with a detached solid/flexible plate at Re=150 is numerically investigated in the present work. Influences of non-dimensional plate length L*, gap distance G* and plate flexibility ω* on vibration responses, flow physics and filament motion are analyzed. For a square cylinder-detached solid plate system, a short plate (L*= 0.25, 0.5) can suppress vortex induced vibration (VIV) in a wide range of G*(0≤G*≤2). In the optimal situation, the vibration can be suppressed almost completely (98% reduction in Ay*). A long solid plate suppresses VIV at a small G*. Nonetheless, it enhances vibration at a large G*. The effective range of G* (range of G* enables VIV suppression) shrinks fast with an increasing plate length. Two mechanisms for an effective VIV suppression are summarized by examining the transient flow fields. On the other hand, a square cylinder-detached flexible plate system maintains a more stable VIV suppression performance within a wide range of G* (0.5≤G*≤2.0) and ω* (0.5≤ω*≤3.0). A more compelling advantage is that, flexibility turns VIV enhancing to VIV suppression at large gap distance (G*=2.0). Although varying flexibility in a wide range gives marginal effect on response statistics, the filament motion undergoes drastic changes. Three types of flapping motion are observed. They are symmetric flapping, asymmetric flapping, and a most interesting one, flow induced reversed flapping (FIRF), which occurs at large gap distance and high flexibility (G*=2.0 and ω*=3.0). The necessary conditions and the onset of reversed flapping are also analyzed. FIRF can be viewed as an automatic gap distance adjusting mechanism. Through it, a shortened gap distance prevents strong and immediate vortex shedding behind the square cylinder, and a good VIV suppression performance can be obtained. This work can help in improving understanding of complex multi-physics coupling FSI problems. Moreover, analyses on VIV responses of a square cylinder-detached plate system can also provide guidance in passive flow control of VIV of a square cylinder.

Investigation of Vortex-Induced Vibration of Double-Deck Truss Girder with Aerodynamic Mitigation Measures

The long-span double-deck truss girder bridge has become a recommend structural form because of its good performance on traffic capacity. However, the vortex-induced vibration (VIV) characteristics for double-deck truss girders are more complicated and there is a lack of related research. In this research, wind tunnel tests were utilized to investigate the VIV characteristics of a large-span double-deck truss girder bridge. Meanwhile, the VIV suppression effect of the aerodynamic mitigation measures was measured. Furthermore, the VIV suppression mechanism was studied from the perspective of vortex shedding characteristics. The results indicated that the double-deck truss girder had a significant VIV when the wind attack angles were +3° and +5°. The aerodynamic mitigation measures had an influence on the VIV response of the double-deck truss girder. The upper chord fairing and lower chord inverted L-shaped deflector plate played a crucial role in suppressing VIV. Numerical analysis indicated that vortex shedding above the upper deck or in the wake region may dominate vertical VIV, while vortex shedding in the wake region of the lower deck may dominate torsional VIV. The upper chord fairing and lower chord inverted L-shaped deflector plate disrupted the original vortex shedding pattern in both regions, thereby suppressing VIV. This research can provide a foundation for bridge design and vibration suppression measures for large-span double-deck truss girder bridges.

Dynamic Response of Two-Degree-of-Freedom Riserless Drill String for Vortex-Induced Vibration Suppression and Enhancement

Dynamic Response of Two-Degree-of-Freedom Riserless Drill String for Vortex-Induced Vibration Suppression and Enhancement

Vortex-Induced vibration suppression for a cylinder with random grooves inspired by rough tree bark

The vortex-induced vibration (VIV) response of a 2-degree-of-freedom cylinder with random grooves is investigated numerically based on the Reynolds Average Navier–Stokes (RANS) method. The Newmark-β method is used to solve the equations of motion of the cylinder. The effects of the random groove on VIV suppression are discussed in detail. The coverage ratios (k) of the random groove include 0%, 25%, 50%, 75%, and 100%. The vibration suppression effect of k = 75% and k = 100% is not significant. However, the VIV amplitude of the cylinders with k = 25% is greatly suppressed. In particular, the cross-flow amplitude ratio is reduced from 1.50 (k = 0%, a smooth cylinder) to 0.65 (k = 25%). First, the boundary-layer separation point of the grooves is fixed, so the random grooves destroy the normal separation and development of the main vortices. Therefore, two rows of vortices with different sizes are generated on both sides of the cylinder, which may cause unstable vibration. Meanwhile, a series of small vortices are formed in the grooves. These small vortices cannot merge synchronously into the main vortices and further reduced the strength of the main vortices. Consequently, the driving force of the vibration, which is generated by the main vortices, is reduced. As a result, the VIV responses are suppressed.