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May 10, 2012, 09:47 
Transition kklomega parameters at inlet

#1 
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Hi!
I'm testing Transition kklomega turbulence model. I was told that this model is very sensitive to initial parameters at flow inlet. So at boundary conditions (in my case pressure inlet) I have to input the value of laminar kinetic energy (kl), but i can`t find any equation in user manual which will help me to estimate this value. Has anybody got information obout estimating of kl for this turbulence model? 

May 11, 2012, 02:03 

#2 
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GavrilovIY
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Hello! I'm interested in this problem too.


May 11, 2012, 03:14 

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I have found some information. In Fluent additional materials it is written that this parameter should be always equal 10^6. Is it correct?


May 11, 2012, 03:39 

#4 
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The only parameter which is important for transition model is the turbulence intensity. 2nd less important parameter is the length scale (in some papers they give value of 0.3 chord as length scale.) but it has little effect as per recent studies(I can send you papers)
Edit : instead of 0.3 chord the correct formula is 0.03 chord or 3% of chord Last edited by Far; May 11, 2012 at 05:08. 

May 11, 2012, 04:58 

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Quote:


May 11, 2012, 05:06 

#6 
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same but for some purpose.
In other models turbulence intensity has no impact (as you are solving the problem fully turbulent). Whereas in transition models increasing/decreasing the turbulence intensity change the behaviour of transition from laminar to turbulent state. 

May 11, 2012, 05:24 

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May 11, 2012, 10:27 
Where did you find the information?

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May 11, 2012, 11:37 

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February 21, 2014, 10:45 

#11  
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Goutam Saha
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Quote:
ranamath06@gmail.com 

February 21, 2014, 11:09 
here you go :)

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February 21, 2014, 12:29 

#13  
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Goutam Saha
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Quote:


June 17, 2016, 14:37 
New model

#15 
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Alberto
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After 8 years, there is a new version (or new model) of the kklomega model.
There are a few problems with the kklomega model in the farfield. One of them is the growth of Laminar Kinetic energy when separation occurs. Lopez and Walters have a paper (have not been published yet) correcting this issue: Maurin Lopez. D. K. Walters. “A recommended correction to the kklomega transition sensitive eddyviscosity model”. Journal of Fluid Engineering. This correction has to be made to the 2008 kklomega model from now on. Now, Lopez and Walters also developed a new transitional model (komegav2) as an alternative to the kklomega one. This new model has more capabilities (it is more reliable) than the kklomega model, especially in the farfield computations. Fortunately the paper for this new model is already publish. Maurin Lopez. D. K. Walters. “Prediction of transitional and fully turbulent free shear flows using an alternative to the laminar kinetic energy approach”. Journal of Turbulence, Vol 17, Iss. 3, 2016. If you see the papers, you will immediately see how the kklomega model is not good for free shear flows, and how the new model corrects all those issues. From now on, kklomega users have to start using the new komegav2 model. Hope this helps 

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