Remove the Turbulence Model

Jem01 · September 22, 2017, 11:16

Hey, how can i remove the turbulence model?

Im using the Channel395 and i want to remove the turbulence model. Is it enough to change the Turbulence model from "WALE" to "laminar" in the turbulence Properties?

I did that, but i kinda get the same results.

Greetings
Jem01

BlnPhoenix · September 25, 2017, 09:27

Quote:

Originally Posted by Jem01

Hey, how can i remove the turbulence model?

Im using the Channel395 and i want to remove the turbulence model. Is it enough to change the Turbulence model from "WALE" to "laminar" in the turbulence Properties?

I did that, but i kinda get the same results.

Greetings
Jem01

Yes, setting to "laminar" is enough to run without turbulence modelling. What kind of results are you expecting?

Jem01 · September 25, 2017, 09:37

Im trying to reconstruct the famous dns channel flow from Kim, Moin, Moser with OpenFOAM.

I Attached my results. S2 is with turbulence model and S3 is without. I Hoped i get closer to the KMM reference by removing the turbulence model, but it dosnt. I also changed the Grid Resolution and the time resolution d^*.

My aime is to get as close to the reference as possible.

Jem01 · September 25, 2017, 09:41

Here proper Attachments

BlnPhoenix · September 25, 2017, 09:45

What is your mesh resolution?

Jem01 · September 25, 2017, 11:24

S1 Resolution = 60 000 (with turbulence Model, d* = 0m3)

S2 Resolution changed from 60 000 to 260 000

S3 Turbulence Model removed

S4 d* from 0,3 changed to 0,03

BlnPhoenix · September 26, 2017, 02:38

Hi, i'm not familiar with the KMM DNS case but a quick google search showed me they used a mesh in the Order of ~3 Mio. cells. So if you want to get there without turbulence modelling (=DNS) there is no alternative to increasing mesh size further, i suppose.

The real question seems why your LES solution is off from reference case. I'm no expert in LES unfortunately but i know that BC's is an important topic. Basically LES solutions are very sensitive to the right inlet/outlet conditions. I would also check the WALE model regarding mesh sizing etc.

Good luck.

September 22, 2017, 11:16	Remove the Turbulence Model	#1
Jem01 New Member Jem Join Date: Dec 2016 Posts: 19 Rep Power: 9	Hey, how can i remove the turbulence model? Im using the Channel395 and i want to remove the turbulence model. Is it enough to change the Turbulence model from "WALE" to "laminar" in the turbulence Properties? I did that, but i kinda get the same results. Greetings Jem01

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Question about matching of solver and turbulence model	louistse	OpenFOAM Running, Solving & CFD	1	February 1, 2017 21:36
Error in Two phase (condensation) modeling	adilsyyed	CFX	15	June 24, 2015 19:42
Overflow Error in Multiphase Modelling with Two Continuous Fluids	ashtonJ	CFX	6	August 11, 2014 14:32
An error has occurred in cfx5solve:	volo87	CFX	5	June 14, 2013 17:44
Wrong calculation of nut in the kOmegaSST turbulence model	FelixL	OpenFOAM Bugs	27	March 27, 2012 09:02

September 25, 2017, 09:45		#5
BlnPhoenix Senior Member Join Date: Aug 2014 Location: Germany Posts: 292 Rep Power: 13	What is your mesh resolution?

September 26, 2017, 02:38		#7
BlnPhoenix Senior Member Join Date: Aug 2014 Location: Germany Posts: 292 Rep Power: 13	Hi, i'm not familiar with the KMM DNS case but a quick google search showed me they used a mesh in the Order of ~3 Mio. cells. So if you want to get there without turbulence modelling (=DNS) there is no alternative to increasing mesh size further, i suppose. The real question seems why your LES solution is off from reference case. I'm no expert in LES unfortunately but i know that BC's is an important topic. Basically LES solutions are very sensitive to the right inlet/outlet conditions. I would also check the WALE model regarding mesh sizing etc. Good luck.