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September 7, 2009, 19:23 
kklw turbulence model

#1 
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Daniel LLanes
Join Date: Aug 2009
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Hi everybody,
I´ve just asked some people what could they tell me about the kklw turbulence model and the answer i´ve got is that it´s a kind of turbulence recently released for commercial versions, and that it has been developed specifically for laminarturbulent transition. Could somebody tell me something more about that? It would be VERY useful for me, i can find no information on the web about it. My other problem is that it´s too difficult for me to get a good convergence on that model, but i do have more time to face this problem. Any website or information about the kklw model? Thank you in advance people 

September 8, 2009, 01:12 

#2 
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Join Date: Mar 2009
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you can find comprehensive information in fluent users's guide and theory guide.
regards 

September 9, 2009, 14:14 

#3 
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Sean Delfel
Join Date: Aug 2009
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Hello,
I've never used that model, but I imagine that modeling transition to turbulence requires a pretty fine mesh. The fluent user's guide should have the info. about grid requirements. sean 

September 9, 2009, 15:22 

#4 
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Daniel LLanes
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Thx for your replies m8s


November 5, 2009, 11:05 

#5 
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Abraham
Join Date: Nov 2009
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sorry for my English, i looking for information about equations of kklw model. i don´t know if kklomega model is the same that kkl model. i see fluent user guide but 3 equations model not appears.
thanks you 

September 19, 2011, 17:12 

#6 
Super Moderator

actually this model is going through the development. first model used the epsilon as turbulent length scale variable. in 2nd phase; model used the omega equation but still epsilon in other two equations. last model, which fluent has I believe, uses the omega equation with omega variable in all other equation.
besides that, there are large changes in other auxiliary equations and limiters (as you there are 24 constants in this model), which are more important to the overall model capability. among them two are very much important : one controls the by pass transition and other controls the natural transition I can send you all three papers for these three versions. 

September 20, 2013, 05:50 

#7 
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Tamara Annabelle
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September 24, 2013, 05:54 

#9 
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Tamara Annabelle
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@Far. I sent you a personal message with my emailadress. Thank you very much!


December 1, 2013, 15:40 

#10 
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saeideh mohamadi
Join Date: Aug 2012
Posts: 229
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Dear Far, whould you please send me the papers related to kklomega?
i really need som information about it. here you are, this my email : saeidehmohamadi@yahoo.com Thank you very much 

March 7, 2014, 13:31 

#11 
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Joao Correia
Join Date: Jul 2012
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SO it's been a while since this topic was last discussed.
I've used the kklw and compared computational with experimental surface flow vis. The results match perfectly with transition being predicted within 2% of the wing chord. But I've only be able to compare these results on a few limited cases. Drag and lift are also within 3% of experimental. Due to issues this turbulence model I've gone back to kw SST, but am suffering from problems as the forces are now 5%drag and 15%lift off! With the kklw I've had flow reversal being created at the outlet, which grows and grows. Checking the the turbulence intensity I've found that there is a spot near the outlet where the side wall and moving ground where turbulence is created....leading divergence sometimes or over 1000 faces having reverse flow on the outlet. My outlet is about 7 body lengths behind the body and upstream of the problematic area turbulence intensity is close to zero. Anyone suffering from the same? Any miracle solutions? 

May 14, 2015, 06:55 

#13 
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ahmed ramadan belal
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Could you send me papers about the model i m going to work on changing some constants of it so i have to know all thing about it


May 22, 2015, 05:04 

#14  
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Jim
Join Date: May 2015
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Quote:
I can confirm what delfel has said. both kklw and transition SST models in fluent require a fine mesh. Fluent reccomend y+ = 1 for the first cell height, and a growth rate of 1.1 in the turbulence modelling lit 

June 17, 2016, 14:35 
New version of the model

#15 
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Alberto
Join Date: Sep 2013
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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 

October 13, 2016, 12:14 

#17 
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Alberto
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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.


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