Journal of Fluid Mechanics



Some characteristics of small-scale turbulence in a turbulent duct flow


R. A.  Antonia a1, J.  Kim a2 and L. W. B.  Browne a1
a1 Department of Mechanical Engineering, University of Newcastle, NSW 2308, Australia
a2 Center for Turbulence Research, NASA-Ames Research Center, Moffett Field, CA 94035, USA

Article author query
antonia ra   [Google Scholar] 
kim j   [Google Scholar] 
browne lw   [Google Scholar] 
 

Abstract

The fine-scale structure of turbulence in a fully developed turbulent duct flow is examined by considering the three-dimensional velocity derivative field obtained from direct numerical simulations at two relatively small Reynolds numbers. The magnitudes of all mean-square derivatives (normalized by wall variables) increase with the Reynolds number, the increase being largest at the wall. These magnitudes are not consistent with the assumption of local isotropy except perhaps near the duct centre-line. When the assumption of local isotropy is relaxed to one of local axisymmetry, or invariance with respect to rotation about a coordinate axis (here chosen in the streamwise direction), satisfactory agreement is indicated by the data outside the wall region. Support for axisymmetry is demonstrated by anisotropy invariant maps of the dissipation and vorticity tensors. The departure from axisymmetry does not appear to be affected by the Reynolds number. Expressions are proposed for approximations to the average energy dissipation and components of the mean-square vorticity. These proposals should allow these quantities to be measured accurately, at least in the present flow.

(Published Online April 26 2006)
(Received December 13 1990)
(Revised May 3 1991)



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