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

#1 
New Member
Join Date: Aug 2011
Posts: 8
Rep Power: 6 
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 
New Member
GavrilovIY
Join Date: Sep 2011
Location: Russian
Posts: 5
Rep Power: 6 
Hello! I'm interested in this problem too.


May 11, 2012, 03:14 

#3 
New Member
Join Date: Aug 2011
Posts: 8
Rep Power: 6 
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 
Super Moderator

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 

#5  
New Member
Join Date: Aug 2011
Posts: 8
Rep Power: 6 
Quote:


May 11, 2012, 05:06 

#6 
Super Moderator

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 

#7  
New Member
Join Date: Aug 2011
Posts: 8
Rep Power: 6 
Quote:


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

#9 
Member
Sheng
Join Date: Jun 2011
Posts: 58
Rep Power: 7 

May 11, 2012, 11:37 

#10 
New Member
Join Date: Aug 2011
Posts: 8
Rep Power: 6 

February 21, 2014, 10:45 

#11  
Senior Member
Goutam Saha
Join Date: Dec 2011
Location: UK
Posts: 131
Rep Power: 6 
Quote:
ranamath06@gmail.com 

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

#12 
Super Moderator


February 21, 2014, 12:29 

#13  
Senior Member
Goutam Saha
Join Date: Dec 2011
Location: UK
Posts: 131
Rep Power: 6 
Quote:


June 17, 2016, 14:37 
New model

#15 
New Member
Alberto
Join Date: Sep 2013
Posts: 21
Rep Power: 4 
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 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Pulsating flow with nonreflective inlet boundary  cc1000  CFX  6  April 27, 2009 08:10 
transitional inlet boundary condition  kamp  CFX  1  June 21, 2006 11:08 
Has anyone successfully used transition modell..p2  PetrK  CFX  12  May 26, 2006 16:27 
Diffusion component at inlet  Balaji  FLUENT  2  August 8, 2005 07:37 
length scales at inlet for internal flows  AnneMarie Giroux  Main CFD Forum  3  July 5, 1999 21:28 