Influence of inlet shear on the 3-D flow past a square cylinder at moderate Reynolds number

Lankadasu, A.; Vengadesan, S.

doi:10.1016/j.jfluidstructs.2009.04.003

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…Its three-dimensional structure appears shifted by half a wavelength after every vortex-shedding cycle, so that the instability would plausibly correspond to mode C, which would have taken precedence over modes A and B following the disruption of the spatial Z 2 symmetry. At Re = 200 and K = 0.2, three-dimensional simulations have shown mode-A-and mode-B-type structures on the low and high velocity halves, respectively, of the wake (Lankadasu & Vengadesan 2009), although nothing similar has been reported elsewhere.…”

Section: Introductionsupporting

confidence: 52%

Square cylinder in the interface of two different velocity streams

Mansy

Sarwar²,

Bergadà³

et al. 2022

J. Fluid Mech.

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We investigate the incompressible flow past a square cylinder immersed in the wake of an upstream nearby splitter plate separating two streams of different velocity. The bottom stream Reynolds number, based on the square side, $Re_B=56$ is kept constant while the top-to-bottom Reynolds numbers ratio $R\equiv Re_T/Re_B$ is increased in the range $R\in [1,6.5]$ , corresponding to a coupled variation of the bulk Reynolds number $Re\equiv (Re_T+Re_B)/2\in [56,210]$ and an equivalent non-dimensional shear parameter $K\equiv 2(R-1)/(R+1)\in [0,1.4667]$ . The onset of vortex shedding is pushed to higher $Re$ as compared with the square cylinder in the classic configuration. The advent of three dimensionality is triggered by a mode-C-type instability, much as reported for open circular rings and square cylinders placed at an incidence. The domain of minimal spanwise-periodic extension that is capable of sustaining spatiotemporally chaotic dynamics, namely one accommodating about twice the wavelength of the dominant eigenmode, has been chosen for the analysis of the wake transition regime. The path towards spatiotemporal chaos is, in this minimal domain, initiated with a modulational period-doubling tertiary bifurcation that also doubles the spanwise periodicity. At slightly higher values of $R$ , the flow has become spatiotemporally chaotic, but the main features of mode C are still clearly distinguishable. Although some of the nonlinear solutions found along the wake transition regime employing the minimal domain might indeed be unstable to long wavelength disturbances, they still are solutions of the infinite cylinder problem and are apt to play a relevant role in the inception of spatiotemporally chaotic dynamics.

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Section: Introductionsupporting

confidence: 52%

Square cylinder in the interface of two different velocity streams

Mansy

Sarwar²,

Bergadà³

et al. 2022

J. Fluid Mech.

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“…It was reported that 2D unsteady RANS solutions have the ability to capture the cessation of the vortex shedding. Square cylinder at moderate Re has been studied by Lankadasu and Vengadesan [8]. That work presented some characteristics that are seen over square cylinders for 3D numerical work for Re = 200.…”

Section: Introductionmentioning

confidence: 93%

“…The unsteady, two-dimensional, Navier-Stokes equations along with the incompressibility constraint have been numerically solved in the present study. The equations for continuity, (7), and momentum, (8), in dimensionless form are given later. It should be noted here that the fluid is assumed as incompressible (i.e., density of the fluid is constant).…”

Section: Mathematical Equationsmentioning

confidence: 99%

Wall proximity effects on flow over cylinders with different cross sections

et al. 2014

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This paper presents the results of a numerical study on flow characteristics over circular, square, and diamond cross-sectional cylinders. Investigations are performed in a two-dimensional domain using the finite volume discretization method solver for Reynolds number, Re = 20 000. Unsteady Reynolds averaged Navier-Stokes equations with Spalart-Allmaras turbulence model have been used as a turbulence closure. After the validation of the simulations with the available experimental data from the open literature, global characteristics of the flow field around different shaped cylinders near the wall have been presented. Effects of wall proximity on cylinders are investigated for four different gap width (G) to cylinder width (D) ratios. Résumé :Nous présentons ici les résultats d'une étude numérique sur les caractéristiques d'écoulement d'un fluide sur la surface de cylindres de section efficace, circulaire, carrée et en diamant. Ces études se font sur un domaine 2D par voie d'une discrétisation en volumes finis, pour une valeur du nombre de Reynolds, Re = 20 000. Nous utilisons les équations de NavierStokes avec décomposition de Reynolds instable, additionnées du modèle de turbulence de Spalart-Allmaras utilisé pour fermer les équations de turbulence. Après validation des résultats à l'aide des résultats expérimentaux provenant de la littérature disponible, nous présentons les caractéristiques globales du champ d'écoulement autour des cylindres de différentes formes près de la couche limite (mur). Nous étudions l'effet de la proximité du mur sur les cylindres, pour quatre différents rapports de largeur d'espacement (G) sur la largeur du cylindre (D). [Traduit par la Rédaction]

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“…No-slip conditions are prescribed on the body surface. At the top and the bottom boundary, in the present work, we have used *ũ/*y = K , v = *w/*y = 0 [11][12][13]. It should be noted that, if the K value is zero, this condition results in symmetry condition, which is the most commonly used far field boundary condition.…”

Section: Introductionmentioning

confidence: 99%

“…This is achieved by using Highly Simplified Marker and Cell algorithm [18]. Basic 680 A. LANKADASU AND S. VENGADESAN validation of the code can be found in [11][12][13]. The time marching calculations were started with the fluid at rest.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation of bluff body wake in planar shear flow

Lankadasu

Vengadesan

2009

Numerical Methods in Fluids

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SUMMARYLarge eddy simulation of planar shear flow past a square cylinder has been investigated. Dynamic Smagorinsky model has been used to model subgrid scale stress. The shear parameter, K , namely the nondimensional streamwise velocity gradient in the lateral direction, is 0.0, 0.1 and 0.2. Reynolds number based on the centerline velocity is fixed at Re = 21 400. The time and span-averaged velocity components, pressure coefficient, Reynolds stresses for uniform are in good agreement with the literature. In shear flow the calculated flow structure and mean velocity components are shown to be markedly different from those of the uniform flow. With increasing shear parameter, the cylinder wake is dominated by clockwise vortices. Both the velocity components in shear flow are compared with respective components in uniform flow. Comparison of normal and shear stresses between shear and no shear case have also been presented.

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Influence of inlet shear on the 3-D flow past a square cylinder at moderate Reynolds number

Cited by 6 publications

References 11 publications

Square cylinder in the interface of two different velocity streams

Square cylinder in the interface of two different velocity streams

Wall proximity effects on flow over cylinders with different cross sections

Large eddy simulation of bluff body wake in planar shear flow

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