|June 1, 2009, 11:57||
Star-CD and K-Epsilon turbulence model
Join Date: Apr 2009
Posts: 50Rep Power: 8
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
K = 3 / 2 * (U * I)
Velocity of Jet . U = 286 m / s
I= Intensity = 5 %
K= 360,73 m2/s2
Epsilon = (cmu 3 / 4) * K (3 / 2) / L
cmu = 0,09,
L= M ixing Length = 0.07
Epsilon = 1,25 e +04
My simulation diverge always
Please I am waiting for your Answers
****** Is this possible ********
|July 16, 2009, 08:54||
Join Date: Mar 2009
Location: Brno, Czech Republic
Posts: 92Rep Power: 8
in fact you may specify the turbulence at inlet also by turb. intensity and length scale (usualy 0.1 - 0.07 of inlet diameter or characteristic size).
With you high velocity do you calculate the flow as compressible and do you have correct setting of the pressure boundary?
what is diverging, epsilon or continuity (pressure)?
|July 31, 2009, 05:34||
Join Date: Jul 2009
Posts: 4Rep Power: 8
I am having a somewhat similar problem. For a model i am only given the intensity and length scale for the turbulence model. How (and where) do I specify them in OF?