Journal of Fluid Mechanics



A description of the organized motion in the turbulent far wake of a cylinder at low Reynolds number


R. A.  Antonia a1, L. W. B.  Browne a1, D. K.  Bisset a1 and L.  Fulachier a2
a1 Department of Mechanical Engineering, University of Newcastle, N.S.W., 2308, Australia
a2 Institut de Mécanique Statistique de la Turbulence, Université d'Aix-Marseille, 13003 Marseille, France

Article author query
antonia ra   [Google Scholar] 
browne lw   [Google Scholar] 
bisset dk   [Google Scholar] 
fulachier l   [Google Scholar] 
 

Abstract

The topology of the organized motion has been obtained in the slightly heated self-preserving far wake of a circular cylinder at a Reynolds number, based on the cylinder diameter, of about 1200. In a frame of reference moving with the organized motion, the toplogy in the plane of main shear reduces to a succession of centres and saddles, located at about the wake half-width. Centres are identifiable by large values of spanwise vorticity associated with the coherent large-scale motion. Saddles occur at the intersection of converging and diverging separatrices, the latter being identifiable with the high strain rate due to the large-scale motion. Large values of the longitudinal turbulence intensity associated with the smaller-scale motion occur at the centres. High values of the normal and shear stresses, the temperature variance and heat fluxes associated with the large-scale motion occur on either side of each saddle point along the direction of the diverging separatrix. Contours for the production of energy and temperature variance associated with the small-scale motion are aligned along the diverging separatrices, and have maxima near the saddle point. Contours for one component of the dissipation of small-scale temperature variance also have a high concentration along the diverging separatrix. Flow visualizations in the far wake suggest the existence of groups of three-dimensional bulges which are made up of clusters of vortex loops.

(Published Online April 21 2006)
(Received August 20 1986)
(Revised March 13 1987)



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