k-epsilon or k-omega or other models which is more appropriate for internal flow?

immortality · May 17, 2013, 00:57

in an internal flow with walls,inlet and outlet which model is more suitable for including both free stream outside of the boundary layer and also near the wall in the boundary layer so that can capture near wall phenomena the best?
Suggestions are appreciated.

jola · May 17, 2013, 02:49

Experts disagree. There is no clear concensus on this. We use SST k-omega for some applications, where secondary flows are strong and a model that is extra conservative for separation predictions is needed. For other applications we user a realizable k-epsilon model, which is easier to work with, converges better and is most often also conservative for separation (not always though)

immortality · May 17, 2013, 07:10

thank you Mr.Larsson
1)If i want to use realizable k-epsilon model how should i treat in the mesh?
I have regions of separation.should i fine the mesh til y+<1 or its sufficinet to be bigger and arround 30?
2)does realizable k-epsilon has an automatic function like kOmegaSST into itself that change to wall function near the wall when 30<y+<60?
Thank you so much.

May 17, 2013, 00:57	k-epsilon or k-omega or other models which is more appropriate for internal flow?	#1
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 26	in an internal flow with walls,inlet and outlet which model is more suitable for including both free stream outside of the boundary layer and also near the wall in the boundary layer so that can capture near wall phenomena the best? Suggestions are appreciated. __________________ Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked.

May 17, 2013, 02:49		#2
jola Administrator Jonas Larsson Join Date: Jan 2009 Location: Gothenburg, Sweden Posts: 824 Rep Power: 10	Experts disagree. There is no clear concensus on this. We use SST k-omega for some applications, where secondary flows are strong and a model that is extra conservative for separation predictions is needed. For other applications we user a realizable k-epsilon model, which is easier to work with, converges better and is most often also conservative for separation (not always though) immortality likes this. Last edited by jola; May 17, 2013 at 03:22.

May 17, 2013, 07:10		#3
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 26	thank you Mr.Larsson 1)If i want to use realizable k-epsilon model how should i treat in the mesh? I have regions of separation.should i fine the mesh til y+<1 or its sufficinet to be bigger and arround 30? 2)does realizable k-epsilon has an automatic function like kOmegaSST into itself that change to wall function near the wall when 30<y+<60? Thank you so much. __________________ Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
reversed flow during RNG in turbulence-k epsilon	Suman Kandula	FLUENT	4	April 2, 2012 07:12
Standard K Epsilon and Transitional SST models	Robin	FLUENT	1	January 17, 2010 18:06
SimpleFoam k and epsilon bounded	nedved	OpenFOAM Running, Solving & CFD	1	November 25, 2008 20:21
justification of the form models of Omega	dali	Main CFD Forum	0	March 25, 2005 04:11
computation about flow around a yawed cone	Tylor Xie	Main CFD Forum	0	June 9, 1999 07:33