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Comparative early development of wake vortices behind a short semicircular-section cylinder in two opposite arrangements

Published online by Cambridge University Press:  26 April 2006

Nathalie Boisaubert ,
Madeleine Coutanceau  and
Patrick Ehrmann
Nathalie Boisaubert
Affiliation:
LMF/LEA, Université de Poitiers, 40, avenue du Recteur Pineau, 86022 Poitiers, France
Madeleine Coutanceau
Affiliation:
LMF/LEA, Université de Poitiers, 40, avenue du Recteur Pineau, 86022 Poitiers, France
Patrick Ehrmann
Affiliation:
LMF/LEA, Université de Poitiers, 40, avenue du Recteur Pineau, 86022 Poitiers, France
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Abstract

As a first step in a more general study of the influence of the body shape upon the initial time-development of wake vortices, we consider the case of a 5.20 aspect-ratio semicircular-section cylinder, fitted with two endplates, and with the rounded side and the flat side in turn facing the oncoming current. The flow structure is analysed by means of a detailed qualitative and quantitative analysis of numerous flow visualization pictures, for Reynolds numbers Re ranging between 60 and 600. Beyond the first phase of development, necessary for the vortex-shedding process to take place (t* [ges ] 6), a change in the flow evolution with Re is found for both body configurations, at a critical Reynolds number Rec whose final value is, within about 5%, 190 and 140 for the rounded and flat forebody respectively. However, this change varies with the body shape. Thus, above Re = 200, it is shown that the reversal of the body compared to the free stream (flat-forebody configuration) implies a clear difference in the wake development with a quasi-symmetrical shifting of the vortex cores to the rear of the recirculating zone and a complete annihilation of the process of vortex shedding, at least during the limited period of time corresponding to the present observation. The consequences of the modifications of the wake behaviour are quantitatively evaluated by considering the time- and Re-evolution of the wake geometrical parameters and of the axial velocity distribution; they are related to the body geometry.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 327 , 25 November 1996 , pp. 73 - 99
Copyright
© 1996 Cambridge University Press

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References

Abed-Meraïm, K. 1992 Etude expérimentale de l'écoulement plan engendré par la translation d’une coque semi-circulaire pour des nombres de Reynolds allant de 0 à 40. Thèse de l’Université de Poitiers.
Barkley, D. & Henderson, R. D. 1996 Three-dimensional Floquet stability analysis of the wake of a circular cylinder. J. Fluid Mech. (to appear).Google Scholar
Boisaubert, N. 1994 Particularités du sillage à l'aval d'un cylindre semi-circulaire, face plane amont ou aval. Rapport de D.E.A. de l'Université de Poitiers.
Bouard, R. & Coutanceau, M. 1980 The early stage of development of the wake behind an impulsively started cylinder for 40 < Re < 10 4. J. Fluid Mech. 101, 583–607.Google Scholar
Chen, Y. M., Ou, Y. R. & Pearlstein, A. J. 1993 Development of the wake behind a circular cylinder impulsively started into rotatory and rectilinear motion. J. Fluid Mech. 253, 449–484.Google Scholar
Collins, W. M. & Dennis, S. C. R. 1973 Flow past an impulsively started circular cylinder. J. Fluid Mech. 60, 105–127.Google Scholar
Coutanceau, M. & Bouard, R. 1977a Experimental determination of the main features of the viscous flow in the wake of a circular cylinder in uniform translation. Part 1. Steady flow. J. Fluid Mech. 79, 231–256.Google Scholar
Coutanceau, M. & Bouard, R. 1977b Experimental determination of the main features of the viscous flow in the wake of a circular cylinder in uniform translation. Part 2. Unsteady flow. J. Fluid Mech. 79, 257–272.Google Scholar
Coutanceau, M., Boyce, P. & Guérineau, G. 1988 Sur le rôle des décollements d'ordre supérieur sur la naissance de l'instabilité secondaire de la frontière d'un cylindre circulaire. C. R. Acad. Sci. Paris (II) 306, 1259–1263.Google Scholar
Coutanceau, M. & Defaye, J. R. 1991 Circular cylinder wake configurations: a flow visualization survey. Appl. Mech. Rev. 44, 255–305.Google Scholar
Coutanceau, M. & Ménard, C. 1985 Influence of rotation on the near-wake development behind an impulsively started circular cylinder. J. Fluid Mech. 158, 399–446.Google Scholar
Dennis, S. C. R., Wang Qiang, Coutanceau, M. & Launay, J. L. 1993 Viscous flow normal to a flat plate at moderate Reynolds numbers. J. Fluid Mech. 248, 605–635.Google Scholar
Ehrmann, P. 1996 Etude comparative de la formation des sillages en fonction de la forme des obstacles. Application à la coque semi-circulaire. Thèse de l'Université de Poitiers.
Ehrmann, P., Boisaubert, N. & Coutanceau, M. 1994 Development of Taylor—Görtler vortices in the near wake of a nominally semi-circular shell. Bull. Am. Phys. Soc. 39, 1948–1949.Google Scholar
Gerich, D. & Eckelmann, H. 1982 Influence of end-plates and free ends on the shedding frequency of circular cylinders. J. Fluid Mech. 122, 109–121.Google Scholar
Gerrard, J. H. 1978 The wakes of cylindrical bluff bodies at low Reynolds numbers. Phil. Trans. R. Soc. Lond. A 288, 351–382.Google Scholar
Green, R. B. & Gerrard, J. H. 1993 Vorticity measurements in the near wake of a circular cylinder at low Reynolds numbers. J. Fluid Mech. 246, 675–691.Google Scholar
Henderson, R. D. & Barkley, D. 1996 Secondary instability in the wake of a circular cylinder. Phys. Fluids (to appear).Google Scholar
Honji, H. & Taneda, S. 1969 Unsteady flow past a circular cylinder. J. Phys. Soc. Japan 27, 1668–1677.Google Scholar
Kalra, T. R. & Uhlherr, P. H. T. 1973 Geometry of bluff body wakes. Can. J. Chem. Engng 51, 655–658.Google Scholar
Karniadakis, G. E. & Triantafyllou, G. S. 1992 Three-dimensional dynamics and transition to turbulence in the wake of bluff objects. J. Fluid Mech. 238, 1–30.Google Scholar
Nagata, H., Nagase, I. & Ito, K. 1989 Unsteady flows past a circular cylinder started impulsively in the Reynolds number range 500 < Re < 104. JSME Intl J. (II) 32, 540–549.Google Scholar
Noack, B. R. & Eckelmann, H. 1994 A global stability analysis of the steady and periodic cylinder wake. J. Fluid Mech. 270, 297–330.Google Scholar
Pineau, G., Texier, A., Coutanceau, M. & Ta Phuoc, Loc 1992 Experimental and numerical visualization of the 3D-flow around a short circular cylinder fitted with end-plates. In Flow Visualization VI (ed. Y. Tanida & H. Miyashiro), pp. 343–347. Springer.
Polidori, G. 1994 Etude par visualisation de sillages tridimensionnels. Application à un profil rectangulaire. Thése de l'Université de Poitiers.
Polidori, G., Pineau, G., Abed Meraïm, K. & Coutanceau, M. 1992 Shedding process of the initial vortices from impulsively started cylinders at Re = 1000: end and body geometry effects. In Bluff-Body Wakes, Dynamics and Instabilities (ed. H. Eckelmann, J. M. R. Graham, P. Huerre & P. A. Monkewitz), pp. 285–288. Springer.
Slaouti, A. & Gerrard, J. H. 1981 An experimental investigation of the end effects on the wake of a circular cylinder towed through water at low Reynolds numbers. J. Fluid Mech. 112, 297–314.Google Scholar
Taneda, S. & Honji, H. 1971 Unsteady flow past a flat plate normal to the direction of motion. J. Phys. Soc. Japan 30, 262–272.Google Scholar
Ta Phuoc, Loc 1980 Numerical analysis of unsteady secondary vortices generated by an impulsively started circular cylinder. J. Fluid Mech. 100, 111–128.Google Scholar
Ta Phuoc, Loc & Bouard, R. 1985 Numerical solution of the early stage of the unsteady viscous flow around a circular cylinder: a comparison with experimental visualization and measurements. J. Fluid Mech. 160, 93–117.Google Scholar
Williamson, C. H. K. 1988 The existence of two stages in the transition to three-dimensionality of a cylinder wake. Phys. Fluids 31, 3165–3168.Google Scholar
Williamson, C. H. K. 1989 Oblique and parallel modes of vortex shedding in the wake of a circular cylinder at low Reynolds numbers. J. Fluid Mech. 206, 579–627.Google Scholar
Williamson, C. H. K. 1992 The natural and forced formation of spot-like ‘vortex dislocations’ in the transition of a wake. J. Fluid Mech. 243, 393–441.Google Scholar
Williamson, C. H. K. 1996 Vortex dynamics in the cylinder wake. Ann. Rev. Fluid Mech. 28, 477–539.Google Scholar
Williamson, C. H. K. 1996 Mode A secondary instability in wake transition. Phys. Fluids 8, 1680–1682.Google Scholar
Williamson, C. H. K. & Prasad, A. 1993 A new mechanism for oblique wave resonance in the ‘natural’ far wake. J. Fluid Mech. 256, 269–313.Google Scholar