Abstract
The purpose of the present work is to study the various specific time scales of the turbulent separating flow around a square cylinder, in order to determine the Reynolds number effect on the separating shear layer, where occurs a transition to turbulence. Unsteady analysis based on large eddy simulation (LES) at intermediate Reynolds numbers and laser doppler velocimetry (LDV) measurements at high Reynolds numbers are carried out. The Reynolds number, based on the cylinder diameter D and the inflow velocity U o , is ranging from Re = 50 to Re = 300,000. A special focus is performed on the coherent structures developing on the sides and in the wake of a square cylinder. For a large Reynolds number range above Re ≈ 1,000, both signatures of Von Karman (VK) and Kelvin–Helmholtz (KH) type vortical structures are found on velocity time samples. The combination of their frequency signature is studied based on Fourier and wavelet analysis. In the present study, We observe the occurrence of KH pairings in the separating shear layer on the side of the cylinder, and confirm the intermittency nature of such a shear flow. These issues concerning the structure of the near wake shear layer which were addressed for the round cylinder case in a recent experimental publication (Rajagopalan and Antonia, Exp Fluids 38:393–402, 2005) are of interest in the present flow configuration as well.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
Balarac, G., Métais, O., Lesieur, M.: Mixing enhancement of coaxial jets through inflow forcing: a numerical study. Phys. Fluids 19, 1–17 (2007)
Bloor, M.S.: The transition to turbulence in the wake of a circular cylinder. J. Fluid Mech. 19, 290 (1964)
Bonnet, J.P., Delville, J.: Review of coherent structures in turbulent free shear flows and their possible influence on computational methods. Flow Turbul. Combust. 66, 333–353 (2001)
Braza, M., Chassaing, P., Ha Minh, H.: Numerical study and physical analysis of the pressure and velocity fields in the near wake of a circular cylinder. J. Fluid Mech. 165, 79 (1986)
Brede, M.: Measurement of turbulence production in the cylinder separated shear-layer using event-triggered laser-doppler anemometry. Exp. Fluids 36, 860–866 (2004)
Brun, C., Goossens, T.: 3d coherent vortices in the turbulent near wake of a square cylinder. Comptes Rendus Mécanique 336(4), 363–369 (2008)
Brun, C., Tenchine, D., Hopfiner, E.J.: Role of the shear layer instability in the near wake behavior of two side-by-side circular cylinders. Exp. Fluids 36(2), 334–343 (2004)
Cherry, N.J., Hillier, R., Latour, M.E.M.P.: Unsteady measurements in a separated and reattaching flow. J. Fluid Mech. 144, 13–46 (1984)
Dong, S., Karniadakis, G.E., Ekmecki, A., Rockwell, D.: A combined direct numerical simulation-particle image velocimetry study of the turbulent near wake. J. Fluid Mech. 569, 185–207 (2006)
Ducros, F., Comte, P., Lesieur, M.: Large-eddy simulation of transition to turbulence in a boundary layer developing spatially over a flat plate. J. Fluid Mech. 326, 1–36 (1996)
Farge, M.: Wavelet transform and their applications to turbulence. Annu. Rev. Fluid. Mech. 24, 395–457 (1992)
Goossens, T.: Etude expérimentale et numérique du sillage turbulent et des forces instationnaires sur un obstacle bi-dimensionnel non profilé. In: Ph.D thesis, Université d’Orléans (2005)
Goossens, T., Brun, C., Doris, L., Hureau, J.: Kelvin–Helmholtz structures in the separated shear layer on the top of a square cylinder: experimental and numerical investigation. In: ETC 11, Trondheim (2004)
Howard, R.J.A., Pourquie, M.: Large eddy simulation of an Ahmed reference model. J. Turbul. 3(1), 12 (2002) Institute of Physics Pub Ltd.
Kim, H.J., Durbin, P.A.: Investigation of the flow between a pair of circular cylinders in the flopping regime. J. Fluid Mech. 196, 431 (1988)
Kourta, A., Boisson, H.C., Chassaing, P., Ha Minh, H.: Non-linear interaction and the transition to turbulence in the wake of a circular cylinder. J. Fluid Mech. 181, 141 (1987)
Lesieur, M., Métais, O.: New trends in large-eddy simulations of turbulence. An. Rev. Fluid. Mech. 28, 45–82 (1996)
Luo, S.C., Chew, Y.T., Ng, Y.T.: Characteristics of square cylinder wake transition fows. Phys. Fluids 17, 1–4 (2003)
Lyn, D.A., Einav, S., Rodi, W., Park, J.-H.: A laser-doppler velocimetry study of ensemble-averaged characteristics of the turbulent near wake of a square cylinder. J. Fluid Mech. 304, 285–319 (1995)
Lyn, D.A., Rodi, W.: The flapping shear layer formed by flow separation from the forward of a square cylinder. J. fluid Mech. 267, 353–376 (1994)
Michalke, A.: On spatially growing disturbances in an inviscid shear layer. J. Fluid Mech. 23(3), 521–544 (1965)
Orlansky, I.: A simple boundary condition for unbounded hyperbolic flows. J. Comp. Phys. 21, 251 (1976)
Prasad, A., Williamson, C.H.K.: The instability of the shear layer separating from a bluff body. J. Fluid Mech. 333, 375 (1997)
Rajagopalan, S., Antonia, R.A.: Flow around a circular cylinder—structure of the near wake shear layer. Exp. Fluids 38, 393–402 (2005)
Rodi, W., Ferziger, J.H., Breuer, M., Pourqui, M.: Status of large eddy simulation: results of a workshop. ASME J. Fluid Eng. 119(2), 248–262 (1997)
Saha, A.K., Biswas, G., Muralidar, K.: Three-dimensional study of flow past a square cylinder at low reynolds numbers. Int. J. Heat Fluid Flow 24, 54–66 (2003)
Sohankar, A., Davidson, L., Norberg, C.: Large eddy simulation on flow past a square cylinder: comparison of different subgridscale models. J. Fluid Eng. 122, 39–47 (2000)
Sohankar, A., Norberg, C., Davidson, L.: Simulation of three-dimensional flow around a square cylinder at moderate reynolds numbers. Phys. Fluids 11, 288–306 (1999)
Thompson, M.C., Hourigan, K.: The shear-layer instability of a circular cylinder wake. Phys. Fluids 17, 1–4 (2005)
Vickery, B.J.: Fluctuating lift and drag on a long cylinder of square cross-section in a smooth and in a turbulent stream. J. fluid Mech. 25, 481–494 (1966)
Wei, T., Smith, C.R.: Secondary vortices in the wake of circular cylinders. J. Fluid Mech. 169, 513 (1986)
Williamson, C.H.K.: Vortex dynamics in the cylinder wake. Annu. Rev. Fluid. Mech. 28, 477 (1996)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Brun, C., Aubrun, S., Goossens, T. et al. Coherent Structures and their Frequency Signature in the Separated Shear Layer on the Sides of a Square Cylinder. Flow Turbulence Combust 81, 97–114 (2008). https://doi.org/10.1007/s10494-008-9152-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10494-008-9152-4