Vortex Shedding Research Articles

Angular vortex-induced vibrations of a cylinder

We consider the response of a flexibly-mounted cylinder placed in flow and free to oscillate on a curved path about a pivot point. The curved path could be concave (i.e., bent toward the incoming flow) or convex (i.e., bent away from the incoming flow). We consider different radii of curvature for both the concave and the convex paths and show that oscillations are observed for radii of curvature larger than one cylinder diameter. In general, we show that the oscillations are of larger amplitudes in the convex orientation, reaching angles of oscillations of up to 38° and normalized (with respect to the cylinder's diameter) amplitudes of oscillations in the transverse and inline directions of up to 1.1 and 0.35, respectively. The oscillations on the concave path are of smaller amplitudes, but last up to higher values of reduced velocities than those in the convex orientation. The shedding and oscillation frequencies increase with increasing reduced velocity for the concave orientation reaching values of around 1.8 times the system's natural frequency in water at the end of the lock-in range, while for the convex orientation, the frequencies stay close to the natural frequency and only jump from values slightly lower than the natural frequency to values slightly higher than the natural frequency when the oscillation amplitude drops from an upper branch to a lower branch in the VIV amplitude response. Two single vortices are observed in the wake when oscillation amplitudes are relatively low, and two pairs of vortices of different sizes are observed in the wake when amplitudes are relatively larger. When two pairs of vortices are observed, the cylinder carries two bound vortices with it during its transverse oscillations and sheds them in the form of a pair of vortices of different sizes at the end of each half cycle. In the cases with the largest amplitudes of oscillations, besides the vortices that are shed synchronized with the oscillation frequency, several smaller-size vortices are shed in the wake as the cylinder traverses its crossflow path. We relate the reason for observing larger amplitudes of oscillations on the convex path to the relative orientation of the fluctuating forces that are exerted on the cylinder due to the shedding of vortices in its wake with respect to its oscillation path.

Evaluation of combustion stability of single and multi-protrusion inserted hybrid rocket motor

The present study explores the influence of protrusions on the combustion stability of a hybrid rocket motor. The primary aim is to analyze single, double, and triple-protrusion configurations taking into account variables such as their location, material, and spacing between them. Protrusions used were made of Nylon (regress during combustion) and graphite (non-regress during combustion). For the base-case (without protrusion), significant pressure oscillations were observed, arising from the interaction between vortex shedding and fundamental longitudinal acoustic modes of the chamber at the fuel grain exit. A protrusion at 0.8X/L (X-protrusion insertion point from head-end, L-fuel grain length) disrupted the interaction between acoustic modes and vortex shedding, substantially dampened its amplitude (around 96% reduction). In case of double (0.2–0.8X/L, 0.5–0.8X/L) and triple-protrusions (0.2–0.5-0.8X/L), the distance between protrusions is playing a key role in inducing the pressure oscillations. When protrusions are kept close (0.5–0.8X/L and 0.2–0.5-0.8X/L), the excitation of third mode acoustics were observed. This was attributed to the continuous increase in protrusion height. If protrusion height exceeds 6–7 mm, the flow over the front protrusion separated and impinges on the subsequent protrusion. This causes pressure oscillations in double and triple-protrusion cases. These pressure oscillations were mitigated using regressable protrusions made of nylon, as they keep the height within the range of 6–7 mm. The results of this research provide valuable perspectives on the significance of protrusions in controlling combustion instability in hybrid rockets.

Numerical investigation of the cavitation effects on the wake dynamics behind a blunt trailing edge hydrofoil

The influence of cavitation on the wake behind a NACA 0009 hydrofoil with a truncated trailing edge has been numerically investigated using a homogeneous mixture model coupled with a controlled decay SST γ-Reθt turbulence model. Using optimal definitions of the inlet turbulent intensity and the empirical condensation and vaporization coefficients of the cavitation model, simulated results have shown a good agreement with experimental data. Notably, the numerical results exhibit negligible deviations of less than 0.7% in vortex shedding frequencies for different cavitation levels. If the size of the vortex cavitation grows, a substantial increase in both lift and drag coefficients on the hydrofoil is observed. Furthermore, the influence of cavitation on the trajectories of vortex centers and the morphology of the primary shedding vortices has been revealed using a vortex identification method. The findings highlight that the cavitation development enhances the advected velocity of the shedding vortices while decreasing the streamwise inter-vortex spacing. Consequently, both factors are found to contribute to the increase of the vortex-shedding frequency behind the NACA 0009 hydrofoil with the truncated trailing edge when cavitation appears and develops.

The research on flow-induced vibration of compact curved tube bundles subjected to liquid cross flow

This paper presents a series of dynamic tests and analyses on single and compactly bundled straight and curved tubes subjected to liquid cross flow. The purpose of this research is to study the flow-induced vibration behavior of compact curved tube bundles, with particular interest in their differences to those of the straight tubes. Both modal and dynamic response tests are performed with tube structures of different bending radius and pitch-diameter ratios. Based on the test results, the vortex shedding phenomenon and Strouhal numbers of single straight tube and single curved tube are analyzed in this paper, and so are the fluid-elastic instability phenomenon and Connors constant of straight tube bundles and curved tube bundles. The test results and analysis conclusions provide valuable assessment tool for the design of helically coiled tube bundles commonly used in steam generators or heat exchangers.

Enhanced Aerodynamic Performance of a Two-Dimensional Airfoil Using Moving Boundaries

The effects of moving boundary conditions on the aerodynamic performance of a two-dimensional NACA 0012 airfoil at different angles of attack (α) in a uniform freestream at a Reynolds number of 10,000 are numerically studied. The moving boundary conditions are motivated by inviscid potential flow around the airfoil, which also satisfies the viscous equations of motion. In this study, the wall is moved at the slip velocity of the inviscid flow, or a fraction of it. These prescribed moving boundary conditions are shown to suppress vortex shedding, thus allowing the drag to go toward zero and the lift coefficient toward 2πα over a wide range of angles of attack (α≤20°) even in the separated flow regime. It is shown that moving boundary conditions are effective over a wide range of their strengths with respect to the overall power required (required to overcome aerodynamic drag and move the airfoil boundary). This power is shown to attain a minimum near the inviscid flow moving boundary condition, which is around 10% or less of the power required for the stationary boundary condition. Finally, the effectiveness of the moving boundary conditions is demonstrated for fully turbulent flow regimes at Re=6 million as well.

Experimental and Computational Investigation of Rotor Noise in Hover

The noise magnitude and directivity of a four-bladed 1.108-m-radius rotor in hover were measured at a tip Mach number of 0.42, representative of an electric vertical takeoff and landing vehicle rotor. The tonal noise was filtered from the acoustic spectra, allowing for analysis of the separate contributions of tonal and broadband noise. Accompanying computations of the same rotor and operating conditions were performed using the rotorcraft comprehensive analysis system (RCAS) with a viscous vortex particle method (VVPM) for aerodynamic calculations and PSU-WOPWOP with the semi-empirical Brooks, Pope, and Marcolini (BPM) broadband model for predicting acoustics. Measured broadband and tonal noise contributed similar magnitudes to the overall sound pressure level, with broadband always several decibels greater. This is in contrast to conventional helicopter rotors, which are dominated by tonal noise. Simulated trends of tonal noise matched the measurements, though the higher harmonic components of the acoustic spectra were underpredicted by up to 30 dB. The broadband noise was underpredicted by 10 dB at moderate rotor collectives, as the measured noise contained noise from laminar and turbulent boundary layers, while the model predicted predominantly laminar boundary layer–vortex shedding noise. Comparing the time histories of the measured and simulated rotor thrust revealed that the RCAS-VVPM method does not capture the amplitude of the 4/rev component of the thrust and lacks the higher frequency content present in the measured thrust, indicating a possible source of discrepancy in the tonal acoustic predictions. The results of this study show that methods to predict rotor tonal and broadband noise without the use of lengthy computational fluid dynamics computations must be further developed.

Effect of pulsating flow on flow-induced vibrations of circular and square cylinders in the laminar regime

Through fluid-structure interaction simulations, this study assesses the dynamic response characteristics of elastically mounted circular and square cylinders subjected to pulsating inflow conditions, providing valuable insights into the analysis and optimization of these systems. The main focus of the present work is on analyzing the effects of two factors: (i) the ratio of the oscillatory velocity component to the steady velocity component in pulsating flow (flow ratio) and (ii) the ratio of the oscillation frequency of pulsating flow to the natural frequency of the structure (frequency ratio). The simulation results for different parameters of interest are analysed using Fourier analysis and Poincaré maps of time series data, and contour plots of vorticity. For the circular cylinder, it is found that cylinder loses synchronization in lock-in as the flow and frequency ratios are increased. Three distinct vibration patterns of vortex-induced vibration are observed for selected combinations of flow and frequency ratios at a Reynolds number of 110 for circular cylinder. For the galloping of square cylinder at a Reynolds number of 250, it is found that the instability and nonlinearity of vortex shedding become more pronounced as the flow ratio increases.

The wake characteristics and hydrodynamic forces of a near-wall circular cylinder with the splitter plate

Flow around a near-wall circular cylinder with the splitter plate is numerically performed at Reynolds number of 500, with the objective of investigating the wake characteristics and hydrodynamic forces. Five gap ratios [Formula: see text] and [Formula: see text] (G is the gap between the lower surface of the cylinder and the wall, D is the diameter of the cylinder) are selected, and the splitter plate length [Formula: see text] ranges from 0 to [Formula: see text]. The flow characteristics of an isolated cylinder with the splitter plate are investigated first for comparison, and four wake flow modes are observed, which include 2S mode ([Formula: see text]), P+S mode ([Formula: see text]), 2S+S mode ([Formula: see text]) and 2P mode ([Formula: see text]). As [Formula: see text] increases from 0 to [Formula: see text], the mean drag coefficient ([Formula: see text]) is decreased, and there is a slight increase of [Formula: see text] for [Formula: see text]. In addition, the cases of [Formula: see text] and [Formula: see text] produce a very significant reduction of drag, and the [Formula: see text] is reduced by as much as [Formula: see text] and [Formula: see text], respectively. The wake characteristics and hydrodynamic forces of a near-wall cylinder with the splitter plate are investigated in detail, and five wake regimes are observed, which include the wake vortex merging regime I, merged vortex attaching regime II, steady flow regime III, wall shear layer elongation regime IV and upper shear layer attaching regime V. For [Formula: see text], the wake vortex shedding is suppressed. For [Formula: see text], the Strouhal number (St) is decreased as [Formula: see text] increases from 0 to 1.0, and there is an increase of St at [Formula: see text]. At [Formula: see text], the St of the near-wall cylinder is larger than that of the isolated cylinder, and the increase in St is affected by the deflected gap flow. What is more, the hydrodynamic characteristics are affected by the wall. For [Formula: see text], the variations of [Formula: see text] with [Formula: see text] are similar to that of the isolated cylinder. It is found that the cases of [Formula: see text] and [Formula: see text] still produce a significant reduction of drag for [Formula: see text], and the [Formula: see text] is increased for all cases of [Formula: see text] as [Formula: see text] increases.

Flow three-dimensionality of wavy elliptic cylinder: vortex shedding bifurcation

The three-dimensional flow of a wavy elliptic cylinder and its wake are investigated for wavelength (λ) to hydraulic diameter (Dm) ratio λ/Dm = 3.43, 4.58, and 6.01. The study aims to gain insights into flow separation, flow dynamics, and three-dimensional flow topologies for the selected wavelengths. Three-dimensional flow structures are visualized through time-averaged streamlines with critical point theory. The results for λ/Dm = 3.43 show spiral flow directed from the node to the saddle, counter-rotating vortices, and a wavy vortex structure. On the contrary, the flows for λ/Dm = 4.58 and 6.01 respectively undergo bifurcation in stable recirculation and vortex shedding on a half-span of the cylinder wavelength. The bifurcation results in a spiral flow toward the saddle and the other spiral flow toward the node. The bifurcations of recirculation and vortex shedding are revealed for the first time. The findings contribute to an improved understanding of the insight into intricate flow physics around wavy elliptic cylinders.

Drag reduction in a spanwise-infinite boat-tailed body through multiple transverse grooves

Appropriately-designed spanwise-extruded small grooves, oriented transverse to the freestream flow, may delay flow separation in adverse pressure gradients by generating local and stable recirculation zones. In this study, we explore the potential of multiple grooves to reduce the drag on a boat-tailed bluff body characterized by vortex shedding. Numerical simulations reveal that the presence of two consecutive transverse grooves results in a maximum boat-tail drag reduction of 23.2%, further decreasing the drag by 15% when compared to the performance of the same boat-tailed bluff body with a single groove. This flow-control mechanism proves effective when the flow reattachment takes place downstream of both grooves throughout the entire vortex-shedding cycle, leading to the formation of two distinct local recirculation zones within the grooves. Lower frictional losses are observed along the streamline bounding the recirculation within the grooves as compared to the friction losses caused by the no-slip boundary conditions along the lateral walls of a plain boat tail (i.e., without grooves). Consequently, the boundary layer exhibits higher momentum downstream of the grooves, resulting in a delayed flow separation and an improved reduction in body drag for the boat tail.

Effect of topographical pattern on vortex shedding and heat transfer phenomena in power-law fluid flow around a rotating cylinder

The present numerical investigation studies the momentum and heat transfer phenomena from a heated rotating patterned cylinder in the vortex shedding regime. In particular, the effect of surface patterns ( ω , δ ), fluid behavior ( 0.4 ≤ n ≤ 1.6 ), cylinder rotation speed ( 0.5 ≤ α ≤ 2 ), and Prandtl number ( 1 ≤ Pr ≤ 100 ) at Reynolds number 100 on the force coefficients and Nusselt number are studied. Vorticity and isotherm profiles demonstrate the flow dynamics and heat transfer characteristics. According to the findings of this study, the formation of the vortex (including its size, shape, and number of vortices) and the time period during which the vortex shedding pattern repeats itself demonstrates a dependency on the shape of the cylinder, fluid behavior, and rotating speed. It has been noted that a significant decrease in the frequency of vortex shedding occurs on adding topographical patterns. Additionally, it has been noticed that on increasing rotational speed, vortex shedding can be suppressed for all fluid behaviors. Numerical simulation results reveal that the average drag coefficient ( C ¯ D ) for a rotating patterned cylinder decreases with increasing rotational speed ( α ), and it further reduces on increase in pattern frequency ( ω ) and amplitude ( δ ) compared to a smooth circular cylinder. The shear-thinning fluid behavior helps to dissipate the heat from the cylinder to the surrounding fluid. Conversely, shear-thickening fluid behavior exhibits the opposite trend.

Numerical research on the wake characteristics and drag reduction of a square cylinder in the presence of control partitions

This study presents the effect of the position of the control partitions on fluid flow around a square cylinder in a rectangular open channel. The numerical simulations are carried out with the lattice Boltzmann method at a fixed Reynolds number (Re=150). In the first case, two downstream partitions are inserted, whose spacing gap (g) varies as a function of the cylinder dimension (d), ranging from 0 to 13d. In the second case, four partitions are implemented such that g is fixed at 3.9d and the upstream spacing varies from 0 to 4d. The numerical results of the first study reveal the existence of a critical spacing at g=3.9d, where the average drag coefficient reaches a minimum (16.28%). Likewise, the vortex shedding between the square cylinder and the two detached partitions or behind these two partitions are also affected. Furthermore, a significant decrease in the drag coefficient, reaching 36.33%, is attained when situating the two upstream partitions at a distance of g1=0.25d.

Mechanism of scour around two piers

AbstractScour around the bridge piers is the main cause of bridge failure below any bridge pier placed within the waterways. It is more than hundred years back a number of researchers described the vortex shedding phenomenon and the resulting Aeolian tones from a circular cylinder. Since then there have been a large number of investigations dealing with various aspects of this phenomenon. In many practical works and situations, flow takes place around more than one obstruction and objects in close proximity. Invariably in all these cases, interference effects occur and the forces on the obstructions are much influenced by these effects. These effects play a key role in the structures like flow-induced vibration of TV and transmission towers, and in many other practical situations. In this research paper the changes in the flow field that occur due to the interference effects are shown, analysed and the results as given in literature are compared with the present experimental work. The features have been brought out in this paper mainly make use of stand and geometry of circular cylinders in close proximity and the flow part of geometry in side by side arrangement.

Tip effects on three-dimensional flow structures over low-aspect-ratio plates: mechanisms of spanwise fluid transport

Three-dimensional flows over low-aspect-ratio rectangular flat plates ( ${A{\kern-4pt}R} = 1.00$ – $1.50$ ) are investigated using tomographic and planar particle image velocimetry techniques. The chord-based Reynolds number is $5400$ , and the angle of attack is fixed at $6^\circ$ . This study reveals for the first time the interplay between spanwise fluid transport and downwash, both originating from the tip effects. Spanwise fluid transport promotes the formation and subsequent coherent development of leading-edge vortices, whereas downwash stabilizes the flow. Specifically, two mechanisms related to spanwise fluid transport are revealed. First, the spanwise fluid transport enhances the intensity of the reversed flow, promoting the shear layer roll-up and vortex shedding. Second, the near-wall spanwise flow interacts with the shed C-shape vortices, thereby strengthening the vortex heads. In particular, through these interactions, spanwise fluid transport can sustain the coherence of the C-shape vortices until the vortex heads split in a regular fashion. Consequently, the C-shape vortices are transformed into novel Þ-shape vortices for the plates of ${A{\kern-4pt}R} \leq 1.25$ , which supplements the previously discovered transformation from C-shape to M-shape vortices for larger ${A{\kern-4pt}R}$ plates. Downstream of this novel vortex-splitting transformation, two fundamental processes contribute to the formation of hairpin vortices. The above comprehensive understanding of complete vortex evolution routine provides valuable insights into the tip effects on the formation of three-dimensional flows over low- ${A{\kern-4pt}R}$ plates.

Simulation of Vortex-Induced Vibration for a Cylinder with Different Rounded Corners under Re = 150

A comprehensive 2D numerical model was conscientiously developed to investigate the vortex-induced vibration phenomena in a cylindrical structure with rounded corners. The Navier-Stokes equation was adeptly solved under the specific condition of a Reynolds number (Re) of 150. The investigation reveals intricate details of the phenomena. The study aimed to systematically analyze the interaction between drag and lift force coefficients, cylinder vibration amplitude, and the patterns of vortex shedding modes under various conditions. This study systematically altered the radius of the cylinder’s rounded corners to evaluate their effects on both structural and hydrodynamic responses. This variation was crucial in comprehending how slight alterations in the cylinder’s geometry impact significant changes in the flow dynamics and correlated vibration behavior. The model’s numerical results revealed the significant impact of the curved edge ratio on both the hydrodynamic forces acting on the cylinder and its vibration response. The variation in edge curvature resulted in changes in drag and lift coefficients, leading to a significant impact on the amplitude of vibration. This elucidates the crucial role of geometric design in controlling and optimizing the structural behavior of cylindrical structures under fluid flow conditions.

Turbulent transports in the flow around a rectangular cylinder with different aspect ratios

The flow around a rectangular cylinder exhibits intricate features, encompassing phenomena such as separation, reattachment, boundary layer transition, and relaminarization. This study explores the intense transport of turbulent fluctuations in these complex flow phenomena, including momentum and turbulent kinetic energy (TKE) transport, for three aspect ratios (L/D=5,10 and 15) at a medium Reynolds number (Re=1000). The connection between these transports and crucial vortical structures is elucidated for the first time. On the lateral side of the cylinder, strong momentum transport occurs, dominated by ejection and sweep events associated with the hairpin vortex. The generation of the LE vortex also leads to active TKE production. The existence of the LE separation bubble, as well as the relaminarization of the downstream boundary layer at L/D=10 and 15, affects the distribution of production terms. This perspective offers an effective yet novel approach that has not been previously addressed in prior researches. The redistribution of TKE results in a disturbance growth, linked to boundary layer transition. The source term reveals that streamwise TKE carried into the recirculating region is closely related to the frequency prior amplified by the LE shear layer. In the wake behind TE, turbulent transports are influenced by vortex shedding patterns.

Control of vortex shedding and acoustic resonance of a circular cylinder in cross-flow

This study experimentally investigates the effectiveness of a control rod in suppressing self-excited acoustic resonance within a range of Reynolds numbers (Re) spanning from 2.1 × 104 to 1.6 × 105. The investigation focuses on specific parameters, including diameter ratio (d/D) values of 0.1, 0.2, and 0.3; gap ratio (G/D) values of 0.05, 0.1, and 0.2; and angular positions (θ) ranging from 0 to 180 degrees. Comparative analyses are conducted between cases featuring the control rod and a reference case (base case) without it. The near-wake flow field is characterized using Particle Image Velocimetry (PIV), and aeroacoustic response measurements are employed to quantify the aeroacoustic noise emission, particularly during self-excited acoustic resonance. Simultaneous measurements of fluctuating lift force and aeroacoustic response measurements, facilitate the quantification of energy transfer from the flow field to the acoustic field during self-excited acoustic resonance. The results reveal that the control rod’s placement significantly impacts the Strouhal periodicity, with outcomes heavily dependent on the rod’s angular orientation. At certain angular positions, the control rod reduces the sound pressure level (SPL) generated during acoustic resonance excitation. However, at different angular positions, the rod exacerbates resonance excitation. This variability is attributed to the control rod’s profound influence on the vortex core formation and the energy transfer mechanism during acoustic resonance.

Enhanced flow induced vibration piezoelectric energy harvesting performance by optimizing tapered beam

This paper proposes a tapered cantilever beam flow induced vibration piezoelectric energy harvester, for optimizing the tapered beam and improving the output characteristics. The physical model of the tapered beam harvester is conceived, a two-dimensional CFD simulation model is established, and experimental validation as well as investigation is conducted. The output voltage and displacement response of the harvesters with various tapered beams are explored. The results show that the tapered beam possesses more uniform strain distribution and larger equivalent stiffness, and increasing the fixed end width results in enhancing output voltage and reducing vibration displacement. The optimal tapered beam with a tip width of 25 mm and fixed end width of 45 mm is obtained. The maximum output voltages of the tapered beam VIVPEH and GPEH are increased by 58.30% and 33.16% over the rectangular beam, respectively. The vibration displacements of the tapered beam VIVPEH and GPEH are reduced by 18.31% and 25.12% over the rectangular beam, respectively. The tapered effect in the flow field reduces the vortex shedding distance, increases the shedding frequency, enhances the aerodynamic forces, and thus improves the energy harvesting performance. This work lays the important foundation for exploring the cantilever beam flow induced vibration harvester system.

Turbulent wake characteristics for a circular cylinder in proximity to a moving wall

This study investigates the scenario of flow past a circular cylinder in proximity to a moving wall (or equally a body translating in still fluid parallel to a stationary wall). Fifty high-fidelity three-dimensional direct numerical simulations are performed over a parameter space of turbulent Reynolds numbers (Re) of 300 to 1000 combined with gap-to-diameter ratios (G/D) of 0.2 to 3. The flow, hydrodynamic and turbulence characteristics over the (Re, G/D) parameter space are examined in detail. Small-scale rib-like mode B structures and alternate vortex shedding are observed for all cases. The streamwise location for the vortex shedding (quantified by the wake recirculation length Lr) varies strongly with both Re and G/D. The variation of Lr with Re and G/D can be explained by the spanwise circulation $\varGamma_z$ fed into the wake, where the variation trends of Lr and $\varGamma_z$ are inversely correlated. The variations of the mean drag and fluctuating lift coefficients are also governed by the variations in Lr and $\varGamma_z$ . The total kinetic energy in the wake region reduces drastically as G/D reduces below 0.8, which is contributed collectively by (i) reduction in the strength of the shed vortices, (ii) downstream movement of the location of vortex shedding and (iii) associated delayed generation of streamwise vortices. The present results on a moving wall also help to explain several flow and hydrodynamic characteristics reported in the literature for a stationary wall, because the moving wall eliminates the complex wall boundary layer and retains a ‘clean’ near-wall effect.

Fluid-solid interaction simulations of an aeroelastic square prism in sinusoidal oscillatory flows

This study numerically investigates the aerodynamic and aeroelastic characteristics of a square prism (aeroelastic model) and wind field around it in sinusoidal oscillatory flows (SOFs). The reliability of the fluid-solid interaction (FSI) simulation is validated by a free vibration test and wind tunnel tests in smooth flow and SOF. The effects of the amplitude and frequency of SOFs are studied at the mean wind speed of vortex-induced resonance. The results show that increasing the amplitude and frequency of SOFs will amplify the root mean square (RMS) along-wind and across-wind base shear forces of the aeroelastic model but decrease the RMS across-wind displacement at the top of the aeroelastic model. The spectral analysis of the base shear forces indicates that the influence of vortex shedding on the across-wind base shear force is reduced by either increasing the amplitude or increasing the frequency of SOFs. The mean and instantaneous wind fields around the aeroelastic model in SOFs and smooth flow are compared, and the wake characteristics of the aeroelastic model in SOFs are analysed by dynamic mode decomposition. It is observed that when the frequency of SOFs is 1.5 times as large as the fundamental natural frequency of the aeroelastic model, the regular vortex shedding process is substantially affected.