On the formation of Taylor-Görtler structures in the vortex induced vibration phenomenon

Pastrana, Daniel; Rodríguez, I.; Cajas, Juan Carlos; Lehmkuhl, O.; Houzeaux, Guillaume

doi:10.1016/j.ijheatfluidflow.2020.108573

Cited by 4 publications

(8 citation statements)

References 61 publications

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“…Moreover, as there is a large wake deficit as a consequence of the large displacement of the cylinder , the drag coefficient is also more than three times the values reported for the static cylinder. In addition to the 2T vortex-shedding pattern, the super-upper branch is characterised by the intermittent emergence of three-dimensional structures of counterrotating streamwise vorticity on the cylinder surface [20]. These structures (see Figure 5) have been shown to be due to the appearance of a centrifugal instability when the cylinder approaches its maximum elongation.…”

Section: Flow Field Salient Featuresmentioning

confidence: 98%

“…Although described in detail in Pastrana et al [16,20], for completeness, a brief summary of the main flow features observed in both the initial and super-upper branches is given. Figure 4 shows the coherent structures and the vortex tubes in the wake of the cylinder in both branches.…”

Section: Flow Field Salient Featuresmentioning

confidence: 99%

“…A later study performed by the same authors showed that when the cylinder is at its maximum elongation in the super-upper branch, Taylor-Görtler structures are formed on the cylinder surface. The appearance of these structures can be attributed to a centrifugal instability occurring twice every vortex-shedding cycle [20].…”

Section: Introductionmentioning

confidence: 99%

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On the Wake Dynamics of an Oscillating Cylinder via Proper Orthogonal Decomposition

Eiximeno

Miró

Cajas

et al. 2022

Fluids

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The coherent structures and wake dynamics of a two-degree-of-freedom vibrating cylinder with a low mass ratio at Re=5300 are investigated by means of proper orthogonal decomposition (POD) of a numerical database generated using large-eddy simulations. Two different reduced velocities of U*=3.0 and U*=5.5, which correspond with the initial and super-upper branches, are considered. This is the first time that this kind of analysis is performed in this kind of system in order to understand the role of large coherent motions on the amplification of the forces. In both branches of response, almost 1000 non-correlated in-time velocity fields have been decomposed using the snapshot method. It is seen that a large number of modes is required to represent 95% of the turbulent kinetic energy of the flow, but the first two modes contain a large percentage of the energy as they represent the wake large-scale vortex tubes. The energy dispersion of the high-order modes is attributed to the cylinder movement in the inline and cross-stream directions. Substantially different POD modes have been found in the two branches. While the first six modes resemble those observed in the static cylinder or in the initial branch of a one-degree of freedom cylinder in the initial branch, the modes not only contain information about the wake vortexes in the super-upper branch but also about the formation of the 2T vortex pattern and the Taylor–Görtler structures. It is shown that the 2T vortex pattern is formed by the interplay between the Taylor–Görtler stream-wise vortical structures and the cylinder movement and is responsible for the increase in the lift force and larger elongation in the super-upper branch.

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Section: Flow Field Salient Featuresmentioning

confidence: 98%

Section: Flow Field Salient Featuresmentioning

confidence: 99%

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On the Wake Dynamics of an Oscillating Cylinder via Proper Orthogonal Decomposition

Eiximeno

Miró

Cajas

et al. 2022

Fluids

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“…Extensive reviews regarding this instability can be found in Hall [42] and Saric [43]. Although most of the studies have been focused on boundary layer instabilities in concave surfaces, Görtler instabilities over convex surfaces, as the case of the circular cylinder, were also recently studied [44,45]. However, whether instabilities here are of a TS type or are triggered by a centrifugal force deserve a more thorough analysis and is beyond the focus of the present study.…”

Section: Time-frequency Analysismentioning

confidence: 99%

On the Characteristics of the Super-Critical Wake behind a Circular Cylinder

Rodríguez

Lehmkuhl

2021

Fluids

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The flow topology of the wake behind a circular cylinder at the super-critical Reynolds number of Re=7.2×105 is investigated by means of large eddy simulations. In spite of the many research works on circular cylinders, there are no studies concerning the main characteristics and topology of the near wake in the super-critical regime. Thus, the present work attempts to fill the gap in the literature and contribute to the analysis of both the unsteady wake and the turbulent statistics of the flow. It is found that although the wake is symmetric and preserves similar traits to those observed in the sub-critical regime, such as the typical two-lobed configuration in the vortex formation zone, important differences are also observed. Owing to the delayed separation of the flow and the transition to turbulence in the attached boundary layer, Reynolds stresses peak in the detached shear layers close to the separation point. The unsteady mean flow is also investigated, and topological critical points are identified in the vortex formation zone and the near wake. Finally, time-frequency analysis is performed by means of wavelets. The study shows that in addition to the vortex shedding frequency, the inception of instabilities that trigger transition to turbulence occurs intermittently in the attached boundary layer and is registered as a phenomenon of variable intensity in time.

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“…The final scheme preserves momentum, angular momentum and kinetic energy at the discrete level. It has been extensively validated for many applications [50][51][52][53][54], in particular, the formulation using WALE and ALE has been previously used to model synthetic jet actuators [14,20]. mesh…”

Section: Case Definition and Modelmentioning

confidence: 99%

Flow topology and heat transfer analysis of slotted and axisymmetric synthetic impinging jets

Miró

Sòria

Cajas

et al. 2021

International Journal of Thermal Sciences

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On the formation of Taylor-Görtler structures in the vortex induced vibration phenomenon

Cited by 4 publications

References 61 publications

On the Wake Dynamics of an Oscillating Cylinder via Proper Orthogonal Decomposition

On the Wake Dynamics of an Oscillating Cylinder via Proper Orthogonal Decomposition

On the Characteristics of the Super-Critical Wake behind a Circular Cylinder

Flow topology and heat transfer analysis of slotted and axisymmetric synthetic impinging jets

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