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-   -   Star-CD and K-Epsilon turbulence model (http://www.cfd-online.com/Forums/star-cd/65015-star-cd-k-epsilon-turbulence-model.html)

hamoudi June 1, 2009 11:19

Star-CD and K-Epsilon turbulence model
 
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 ********






gmg June 2, 2009 13:00

Hi
 
Hi,
can I get your one which you are doing.. because I am working on k-e model.

thanks

gmg

gmg June 2, 2009 13:02

Hi
 
my e-mail address is mustafa_ruet@yahoo.com.

thanks.

SKK June 5, 2009 06:02

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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