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The subgrid-scale scalar variance under supercritical pressure conditions

Masi, Enrica and Bellan, Josette (2011) The subgrid-scale scalar variance under supercritical pressure conditions. Physics of Fluids, 23 (8). Art. No. 085101 . ISSN 1070-6631.

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To model the subgrid-scale (SGS) scalar variance under supercritical-pressure conditions, an equation is first derived for it. This equation is considerably more complex than its equivalent for atmospheric-pressure conditions. Using a previously created direct numerical simulation (DNS) database of transitional states obtained for binary-species systems in the context of temporal mixing layers, the activity of terms in this equation is evaluated, and it is found that some of these new terms have magnitude comparable to that of governing terms in the classical equation. Most prominent among these new terms are those expressing the variation of diffusivity with thermodynamic variables and Soret terms having dissipative effects. Since models are not available for these new terms that would enable solving the SGS scalar variance equation, the adopted strategy is to directly model the SGS scalar variance. Two models are investigated for this quantity, both developed in the context of compressible flows. The first one is based on an approximate deconvolution approach and the second one is a gradient-like model which relies on a dynamic procedure using the Leonard term expansion. Both models are successful in reproducing the SGS scalar variance extracted from the filtered DNS database, and moreover, when used in the framework of a probability density function (PDF) approach in conjunction with the β-PDF, they excellently reproduce a filtered quantity which is a function of the scalar. For the dynamic model, the proportionality coefficient spans a small range of values through the layer cross-stream coordinate, boding well for the stability of large eddy simulations using this model.

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Additional Information:© 2011 American Institute of Physics. Received 23 February 2011; accepted 9 June 2011; published online 1 August 2011. This study was conducted at the Jet Propulsion Laboratory (JPL) of the California Institute of Technology (Caltech) under sponsorship of the U.S. Department of Energy and of the U.S. Air Force Office of Scientific Research. Computational resources were provided by the supercomputing facility at JPL.
Funding AgencyGrant Number
Department of Energy (DOE)UNSPECIFIED
Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
Subject Keywords:compressible flow, flow simulation, mixing, numerical analysis, thermal diffusion, turbulent diffusion
Classification Code:PACS: 47.27.tb; 47.27.wj; 47.40.-x; 47.51.+a; 47.11.-j; 47.27.ek
Record Number:CaltechAUTHORS:20110921-110133253
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25386
Deposited By: Tony Diaz
Deposited On:27 Sep 2011 22:20
Last Modified:26 Dec 2012 13:41

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