Computation of the Starting Vortex Flow Past a Flat Plate

Xu, Ling; Nitsche, Monika; Krasny, Robert

doi:10.1016/j.piutam.2017.03.019

Cited by 10 publications

(6 citation statements)

References 7 publications

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“…For example, figure 4(e) of Pullin & Perry (1980) shows reasonable agreement between experiment and the inviscid theory (for z c ) for wedges and thin plates with Re t ∼ 10 3 -10 6 . Similarly, Xu et al (2017) report good agreement between viscous and inviscid solutions for the location, size and shape of the vorticity spiral vortex cores, and also for the shed circulation as a function of time, for Re c = 250-2000. These previous studies suggest that similar agreement may be found for the present problem in this limit of very small convective time, T 1, at moderately large Re t .…”

Section: Type I Vortex Sheetmentioning

confidence: 58%

“…Luchini & Tognaccini (2017) compared these motions with their counterpart found in inviscid starting-vortex simulations. Xu, Nitsche & Krasny (2017) made detailed comparisons of regularized, inviscid spiral-like solutions with viscous simulations for the impulsive, non-rotating starting flow of a finite flat plate at Reynolds numbers between 250 and 2000. Good agreement was reported for large-scale features of the flow.…”

Section: Introductionmentioning

confidence: 99%

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On the starting vortex generated by a translating and rotating flat plate

Pullin

Sader

2020

J. Fluid Mech.

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Section: Type I Vortex Sheetmentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

On the starting vortex generated by a translating and rotating flat plate

Pullin

Sader

2020

J. Fluid Mech.

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“…In this model, vortex sheets approximate the thin viscous boundary layers along the body, which are advected from its trailing edge into the flow downstream. This can be regarded as the inviscid limit of the viscous flow, and gives a good representation of the large-scale features of the flow and the vortex wake dynamics at Reynolds numbers of O(10 2 -10 5 ) [31,39,40]. These flows are challenging to simulate directly due to the need to resolve sharp layers of vorticity in the vicinity of an unsteady, possibly deforming solid boundary.…”

Section: Introductionmentioning

confidence: 99%

Large-amplitude membrane flutter in inviscid flow

Mavroyiakoumou

Alben

2020

J. Fluid Mech.

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We study the large-amplitude flutter of membranes (of zero bending rigidity) with vortex-sheet wakes in 2D inviscid fluid flows. We apply small initial deflections and track their exponential decay or growth and subsequent large-amplitude dynamics in the space of three dimensionless parameters: membrane pretension, mass density, and stretching modulus. With both ends fixed, all the membranes converge to steady deflected shapes with single humps that are nearly fore-aft symmetric, except when the deformations are unrealistically large. With leading edges fixed and trailing edges free, the membranes flutter with very small amplitudes and high spatial and temporal frequencies at small mass density. As mass density increases, the membranes transition to periodic and then increasingly aperiodic motions, and the amplitudes increase and spatial and temporal frequencies decrease. With both edges free, the membranes flutter similarly to the fixedfree case but also translate vertically with steady, periodic, or aperiodic trajectories, and with nonzero slopes that lead to small angles of attack with respect to the oncoming

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“…We have employed the non-uniform blob regularization for the longtime computation of free vortex sheets. It was shown numerically that the vortex blob method reproduces many features associated with the Navier-Stokes solution with increasing Reynolds number [52,53]. However, a direct link of the δ-parameter and the physical effects such as viscosity or layer thickness has not yet been established.…”

Section: Discussionmentioning

confidence: 99%

“…21 and 22. We refer to Xu, Nitsche and Krasny [52] for the simulation for the same problem in this section by using the vortex sheet model, in comparison with the Navier-Stokes simulations for varying Reynolds numbers.…”

Section: Comparison With the Previous Modelmentioning

confidence: 99%

An inviscid model of unsteady separated vortical flow for a moving plate

Sohn

2020

Theor. Comput. Fluid Dyn.

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An inviscid vortex shedding model for separated vortices from a solid body is studied. The model describes the separated vortices by vortex sheets and the attached flow via conformal mapping. We develop a computational model to simulate the vortex shedding of a moving body, with varying angle. An unsteady Kutta condition is imposed on the edges of the plate to determine the edge circulations and velocities. The force on the plate is obtained by integrating the unsteady Blasius equation. We apply the model to two representative cases of an accelerated plate, with impulsive start and uniform acceleration, and investigate the dynamics for large angles of attack. For both cases, the vortex force is dominant in the lift over times. The lift coefficients are initially high and decrease in four chord lengths of displacement, in general. For large angles of attack, the appearance of a peak of lift at an early time depends on the power-law velocity, which differs from the behavior for small angles of attack. The lift and drag from the model are in agreement with the Navier-Stokes simulation and experiment for moderate Reynolds numbers. We also demonstrate the vortex shedding of hovering and flapping plates. In the hovering motion, the large increase in lift at the early backward translation is due to the combined effect of the vortex force and added mass force. In the flapping plate, our model provides an improvement in the prediction for the induced force than other shedding models.The flight of insects and birds has attracted much attention for the past decades owing to its potential applications to microair vehicles. It has been shown that the conventional aerodynamic theory based on steady flows cannot explain the generation of large lift by small insects, and therefore, unsteady aerodynamics should be considered. Typical flapping-wing animals fly in the regime of Reynolds number 10-10,000 and employ high angles of attack. Various aerodynamic mechanisms have been proposed for lift generation of hovering flights [1][2][3][4][5].Unsteady vortex separation during the thrust stroke of the wing motion plays a crucial role in the production of forces in the flapping flight [6]. At high Reynolds numbers, the diffusion of vorticity is negligible compared with its inertial motion; hence, the evolution of the separated flow can be approximated by the inviscid vortex particles. The early vortex models by Wagner [7] and von Karman and Sears [8] included only the trailing-edge vortex. These models admit analytical solutions by assuming that the vortex particles are fixed after deposition, but are applicable to small angles of attack.The main approaches for modeling of the unsteady separated vortical flow are categorized into two classes: discontinuous models (point vortices) and continuous models (vortex sheets). The former models [9-11] release Communicated

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Computation of the Starting Vortex Flow Past a Flat Plate

Cited by 10 publications

References 7 publications

On the starting vortex generated by a translating and rotating flat plate

On the starting vortex generated by a translating and rotating flat plate

Large-amplitude membrane flutter in inviscid flow

An inviscid model of unsteady separated vortical flow for a moving plate

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