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extracting K and Epsilon from Spalart Allmaras

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Old   July 6, 2006, 00:11
Default extracting K and Epsilon from Spalart Allmaras
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Sundar
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Hi, I am working in an Aeroacoustics of Jet. Based on the paper by Craig Hunter, I have developed a code to calculate the SPL for the jets. I use Fluent to compute the flow.

The aeroacoustic code requires K, Epsilon and the Reynolds stresses to calculate the SPL. We are trying to test different turbulence model to match our experiments, and we beleive that Spalart Allmaras model might have good conformance with the results.

Now, as the Spalart Allmaras model is based on Eddy viscosity, the question arises of how to calculate the terms K and Epsilon.

Can anyone throw a light on that?

Regards, Sundar
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Old   July 7, 2006, 05:08
Default Re: extracting K and Epsilon from Spalart Allmaras
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mar
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I don't think that Spalart-Allmaras is a good choice because this model has been developed for airfoil configurations (it contains a notion of distance from the wall). Anyway it is not correct to obtain k and eps from the eddy viscosity because the relation is not invertible (you cannot obtain 2 parameters from one). The only think you can do is to suppose that Spalart Allmaras contains the same hypotesis of the one equation model (which is an equation in k) and use this relation to obtain only k. However this hypothesis is not so smart for jet-noise prediction!!!
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Old   July 7, 2006, 05:13
Default Re: extracting K and Epsilon from Spalart Allmaras
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Sundar
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I was thinking the same. Thanks for your inputs. As an additional information from my study, when I tried with different turbulence models (in Fluent), Spalart Allmaras model had the highest velocity decay.
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Old   July 30, 2006, 03:34
Default Re: extracting K and Epsilon from Spalart Allmaras
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davood rashidi
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I need information about SPALART ALLMARAS model. beacuse of I want use this model for solve my final MS poroject. pleas help me. thancks alot davood rashidi aerodynamic engineer from KNTU univercity
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Old   July 31, 2006, 02:02
Default Re: extracting K and Epsilon from Spalart Allmaras
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mar
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The main paper is:

P.R. Spalart and S.R. Allmaras, A one equation turbulence model for aerodynamic flows. La Recerche Aerospatiale 1994; 1:5-21.

using Google you can find many papers in which this model is used.
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