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Star-CD and K-Epsilon turbulence model

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Old   June 1, 2009, 11:19
Default Star-CD and K-Epsilon turbulence model
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Hamoudi djamel
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Hello Everybody,

I have a simulation on a numerical jet of air For this I use the Star-CD with Turbulence Model K-epsilon
as you know at the beginning of the simulation we need to initialize the values of
K and epsilon ( Energy and Dissipation rate of turbulence )
to calculate these two parameters
Energy
K = 3 / 2 * (U * I)
Velocity of Jet . U = 286 m / s
I= Intensity = 5 %
K= 360,73 m2/s2

Epsilon

Epsilon = (cmu 3 / 4) * K (3 / 2) / L



cmu = 0,09,

L= Mixing Length = 0.07


Epsilon = 1,25 e +04


My simulation diverge always


Please I am waiting for your Answers



****** Is this possible ********





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Old   June 2, 2009, 13:00
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gmg
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Hi,
can I get your one which you are doing.. because I am working on k-e model.

thanks

gmg
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Old   June 2, 2009, 13:02
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gmg
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my e-mail address is mustafa_ruet@yahoo.com.

thanks.
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Old   June 5, 2009, 06:02
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Try using smaller URF for k and e to start the case and then later on increase as the solution has run for a few iterations and stabilised. You could also initiate the solution with smaller value of k. General k-e models under-predict the 'spread' of k values from meanline in jet modeling.
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