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Toward Better Modeling of Supercritical Turbulent Mixingstudy was done as part of an effort to develop computational models representing turbulent mixing under thermodynamic supercritical (here, high pressure) conditions. The question was whether the large-eddy simulation (LES) approach, developed previously for atmospheric-pressure compressible-perfect-gas and incompressible flows, can be extended to real-gas non-ideal (including supercritical) fluid mixtures. [In LES, the governing equations are approximated such that the flow field is spatially filtered and subgrid-scale (SGS) phenomena are represented by models.] The study included analyses of results from direct numerical simulation (DNS) of several such mixing layers based on the Navier-Stokes, total-energy, and conservation- of-chemical-species governing equations. Comparison of LES and DNS results revealed the need to augment the atmospheric- pressure LES equations with additional SGS momentum and energy terms. These new terms are the direct result of high-density-gradient-magnitude regions found in the DNS and observed experimentally under fully turbulent flow conditions. A model has been derived for the new term in the momentum equation and was found to perform well at small filter size but to deteriorate with increasing filter size. Several alternative models were derived for the new SGS term in the energy equation that would need further investigations to determine if they are too computationally intensive in LES.
Document ID
20080048187
Acquisition Source
Jet Propulsion Laboratory
Document Type
Other - NASA Tech Brief
Authors
Selle, Laurent
(California Inst. of Tech. Pasadena, CA, United States)
Okongo'o, Nora
(California Inst. of Tech. Pasadena, CA, United States)
Bellan, Josette
(California Inst. of Tech. Pasadena, CA, United States)
Harstad, Kenneth
(California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 24, 2013
Publication Date
September 1, 2008
Publication Information
Publication: NASA Tech Briefs, September 2008
Subject Category
Man/System Technology And Life Support
Report/Patent Number
NPO-44402
Distribution Limits
Public
Copyright
Public Use Permitted.
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