Application
of HPIV data of turbulent duct flow for turbulence modeling
Bo Tao, Joseph Katz and Charles Meneveau
Department of Mechanical Engineering
The Johns Hopkins University, Baltimore, MD 21218
ABSTRACT: Holographic PIV is used to measure the three-
dimensional velocity distribution of fully developed turbulent
flow within a square duct at ReH = 1.2 x 10^5. The data is
used for mapping the structure of the filtered, three-dimensional
vorticity, strain-rate and subgrid-scale stress tensor distributions.
Visualizations of iso-vorticity surfaces show structures
that are only slightly elongated, as opposed to the long
and thin "worms" observed in DNS for unfiltered
turbulence. The structure of these fields is studied further
by measuring absolute and relative orientations of characteristic
vectors. The fluctuating vorticity has a preferred direction
aligned at about 45? to the mean flow. The preferential alignment
of the vorticity with the intermediate eigenvector of the
strain-rate tensor observed previously in DNS data is also
found in this high Reynolds number shear flow. The PDF of
the intermediate eigenvalue shows some differences compared
to DNS results. Two of the SGS stress eigenvectors are nearly
randomly aligned compared to the most extensive and intermediate
eigenvectors of the strain-rate tensor. In contrast, the
most extensive stress eigenvector has a significant correlation
with the direction of the most compressible strain-rate eigendirection.
These results help to shed light on the relative success
of eddy viscosity models in predicting the SGS dissipation,
but their failure in predicting the actual stresses. In addition,
the observed preferential alignments of the vorticity with
two stress eigendirections may point to new modeling approaches
based on vorticity.
in:
Proceedings of ASME FEDSM99
ASME 2000 Fluids Engineering Division Summer Meeting
paper: FEDSM99-7281 (1999)
Full
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(©ASME,
see http://www.aps.org).