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On the Alignment of Strain, Vorticity and Scalar Gradient in Turbulent, Buoyant, Nonpremixed FlamesThe alignment of vorticity and scalar gradient with the eigendirections of the rate of strain tensor is investigated in turbulent buoyant nonpremixed horizontal and vertical flames. The uniqueness of a buoyant nonpremixed flame is that it contains regions with distinct alignment characteristics. The strain-enstrophy angle Psi is used to identify these regions. Examination of the vorticity field and the vorticity production in these different regions indicates that Psi and consequently the alignment properties near the flame surface identified by the mixture fraction band F approximately equals F(sub st) differ from those in the fuel region, F > F(sub st) and the oxidizer region, F < F(sub st). The F approximately equals F(sub st) band shows strain-dominance resulting in vorticity/alpha alignment while F > F(sub st) (and F < F(sub st) for the vertical flame) band(s) show(s) vorticity/beta alignment. The implication of this result is that the scalar dissipation, epsilon(sub F), attains its maximum value always near F approximately equals F(sub st). These results are also discussed within the framework of recent dynamical results [Galanti et al., Nonlinearity 10, 1675 (1997)] suggesting that the Navier-Stokes equations evolved towards an attracting solution. It is shown that the properties of such an attracting solution are also consistent with our results of buoyant turbulent nonpremixed flames.
Document ID
20000030670
Acquisition Source
Legacy CDMS
Document Type
Preprint (Draft being sent to journal)
External Source(s)
Authors
Boratav, O. N.
(California Univ. Irvine, CA United States)
Elghobashi, S. E.
(California Univ. Irvine, CA United States)
Zhong, R.
(California Univ. Irvine, CA United States)
Date Acquired
September 7, 2013
Publication Date
September 1, 1999
Publication Information
Publication: Physics of Fluids
Publisher: American Inst. of Physics
Volume: 10
Issue: 9
ISSN: 1070-6631
Subject Category
Inorganic, Organic And Physical Chemistry
Report/Patent Number
ISSN: 1070-6631
Funding Number(s)
PROJECT: RTOP 101-53
CONTRACT_GRANT: NGT3-52300
Distribution Limits
Public
Copyright
Public Use Permitted.
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