Skip to main content
×
Home
    • Aa
    • Aa

Critical points in a turbulent near wake

  • Y. Zhou (a1) and R. A. Antonia (a1)
Abstract

Velocity data were obtained in the turbulent wake of a circular cylinder with an orthogonal array of sixteen X-wires, eight in the (x, y)-plane and eight in the (x, z)-plane. By applying the phase-plane technique to these data, three types of critical points (where the velocity is zero and the streamline slope is indeterminate) were identified. Of these, foci and saddle points occurred most frequently, although a significant number of nodes was also found. Flow topology and properties associated with these points were obtained in each plane. Saddle-point regions associated with spanwise vortices provide the dominant contribution to the Reynolds shear stress and larger contributions to the normal stresses than focal regions. The topology was found to be in close agreement with that obtained from other methods of detecting features of the organized motion. The inter-relationship between critical points simultaneously identified in the two planes can provide some insight into the three-dimensionality of the organized motion. Foci in the (x, z)-plane correspond, with relatively high probability and almost negligible streamwise separation, to saddle points in the (x, y)-plane and are interpreted in terms of ribs aligned with the diverging separatrix between consecutive spanwise vortex rolls. Foci in the (x, z)-plane which correspond, with relatively weak probability, to foci in the (x, y)-plane seem consistent with a distortion of the vortex rolls in the (y, z)-plane.

Copyright
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

Bisset, D. K., Antonia, R. A. & Britz, D. 1990a Structure of large-scale vorticity in a turbulent far wake. J. Fluid Mech. 218, 463482.

Bisset, D. K., Antonia, R. A. & Browne, L. W. B. 1990b Spatial organization of large structures in the turbulent far wake of a cylinder. J. Fluid Mech. 218, 439461.

Cantwell, B. J., Coles, D. & Dimotakis, P. E. 1978 Structure and entrainment in the plane of symmetry of a turbulent spot. J. Fluid Mech. 87, 641672.

Chong, M. S., Perry, A. E. & Cantwell, B.1990A general classification of three-dimensional flow patterns. Phys. Fluids A 2, 767777.

Hayakawa, M. & Hussain, F. 1989 Three-dimensionality of organized structures in a plane turbulent wake. J. Fluid Mech. 206, 375404.

Hunt, J. C. R. Abell, C. J., Peterka, J. A. & Woo, H. 1978 Kinematical studies of the flows around free or surface-mounted obstacles, applying topology to flow visualization. J. Fluid Mech. 86, 179200.

Hussain, A. K. M. F. & Hayakawa, M. 1987 Education of large-scale organized structures in a turbulent plane wake. J. Fluid Mech. 180, 193229.

Kiya, M. & Matsumura, M.1985Turbulence structure in intermediate wake of a circular cylinder. Bull. JSME28, 26172624.

Kiya, M. & Matsumura, M. 1988 Incoherent turbulence structure in the near wake of a normal plate. J. Fluid Mech. 190, 343356.

Meiburg, E. & Lasheras, J. C.1987Comparison between experiments and numerical simulations of three-dimensional plane wakes. Phys. Fluids30, 623625.

Perry, A. E. & Chong, M. S.1987A description of eddying motions and flow patterns using critical-point concepts. Ann. Rev. Fluid Mech.19, 125155.

Robinson, S. K.1991Coherent motions in the turbulent boundary layer. Ann. Rev. Fluid Mech.23, 601639.

Smith, J. H. B.1972Remarks on the structure of conical flow. Prog. Aeronaut. Sci.12, 241272.

Soria, J. & Cantwell, B. J.1993The identification and classification of topological structures in free shear flows. In Eddy Structure Identification in Turbulent Shear Flows (ed. M. N.Glauser & J.-P.Bonnet), pp. 379390. Kluwer.

Williamson, C. H. K.1988The existence of two stages in the transition to three-dimensionality of a cylinder wake. Phys. Fluids31, 31563168.

Zhou, Y. & Antonia, R. A.1992Convection velocity measurements in a cylinder wake. Exps Fluids13, 6370.

Zhou, Y. & Antonia, R. A. 1993a A study of turbulent vortices in the near wake of a cylinder. J. Fluid Mech. 253, 643661.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×
MathJax