CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

LowRe RANS turbulence models

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree7Likes
  • 1 Post By eugene
  • 4 Post By hjasak
  • 2 Post By yohannperrot

Reply
 
LinkBack Thread Tools Display Modes
Old   January 10, 2006, 14:22
Default Hi all, I have some doubts,
  #1
Member
 
Luca M.
Join Date: Mar 2009
Location: Luzern, Switzerland
Posts: 59
Rep Power: 8
luca is on a distinguished road
Hi all,

I have some doubts,

OpenFOAM supports Low-Reynolds RANS Turbulence Models?
How can I activate Low-Reynolds Turbulence Models in OpenFOAM for RANS calculations?!

Thanks
luca is offline   Reply With Quote

Old   January 10, 2006, 14:34
Default Choose LienCubicKELowRe, Lie
  #2
Senior Member
 
Eugene de Villiers
Join Date: Mar 2009
Posts: 725
Rep Power: 12
eugene is on a distinguished road
Choose
LienCubicKELowRe,
LienLeschzinerLowRe
or SpalartAllmaras

as your turbulence model. Make sure all turbulent variables are set to zero (or 1e-20) on the boundary and off you go.
fumiya likes this.
eugene is offline   Reply With Quote

Old   January 10, 2006, 14:39
Default You're probably better off wit
  #3
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,763
Rep Power: 21
hjasak will become famous soon enough
You're probably better off with one of these instead:

- LaunderSharma. My choice - I wouldn't say it's special, but it's a very decent choice. Requires the first cell to be below y+ = 1
- LamBremhorstKE. That's the standard reference, but needs distance to the wall everywhere. More sensitive to the near-wall resolution
- QZeta. Nice - a reformulation of LaunderSharma in better variables (lower resolution requirements).

Enjoy,

Hrv
chegdan, fumiya, 1/153 and 1 others like this.
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   January 11, 2006, 10:31
Default First, thank you very much for
  #4
Member
 
Luca M.
Join Date: Mar 2009
Location: Luzern, Switzerland
Posts: 59
Rep Power: 8
luca is on a distinguished road
First, thank you very much for the answers.

but when i write, for example, "LienCubicKELowRe" in turbulenceProperties file i receive this message:

FOAM FATAL ERROR : Unknown turbulenceModel type LienLeschzinerLowRe

Valid turbulenceModel types are :

7
(
kEpsilon
realizableKE
LaunderSharmaKE
laminar
RNGkEpsilon
LRR
LaunderGibsonRSTM
)

So it's not clear how can i set low-Re turbulence models in RANS compressible calculations.
Moreover, when i set LaunderSharma for Low-Re turbulence model simulation i have to digit "LaunderSharmaLowRe" in turbulenceProperties file ?!

sorry but i have some difficult

thanks in advance again

Luca
luca is offline   Reply With Quote

Old   January 11, 2006, 10:46
Default For compressible flows, we've
  #5
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,763
Rep Power: 21
hjasak will become famous soon enough
For compressible flows, we've only got LaunderSharmaKE for low-Re simulations.

constant/turbulenceProperties:

turbulenceModel LaunderSharmaKE;



I don't understand the second part of the question, sorry.

Hrv
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   January 11, 2006, 11:57
Default sorry for the confusion in the
  #6
Member
 
Luca M.
Join Date: Mar 2009
Location: Luzern, Switzerland
Posts: 59
Rep Power: 8
luca is on a distinguished road
sorry for the confusion in the last phrase..

your answer is enough for my doubt.

Best regards

Luca
luca is offline   Reply With Quote

Old   July 19, 2006, 09:51
Default I am trying to use Launder-Sha
  #7
diego_n
Guest
 
Posts: n/a
I am trying to use Launder-Sharma lo-Re compressible model which, standing on literature, requires a zero value for epsiln at wall.
By setting epsilon equal to 0 at wall I obtain a singularity error, while it runs using a zeroGradient boundary at wall.
Which boundary do you use for this model?
  Reply With Quote

Old   July 20, 2006, 04:06
Default In any CFD software, avoid as
  #8
New Member
 
Yohann PERROT
Join Date: Mar 2009
Posts: 2
Rep Power: 0
yohannperrot is on a distinguished road
In any CFD software, avoid as much as possible setting 0 to values which are used as a denominator somewhere in the code (so as to avoid infinity values, undetermined forms and so on). Put a low number close to zero like 1.e-10 instead.

Good Luck
fumiya and 1/153 like this.
yohannperrot is offline   Reply With Quote

Old   October 4, 2007, 11:06
Default Hi, can anyone give me the re
  #9
Member
 
Rolando Maier
Join Date: Mar 2009
Posts: 89
Rep Power: 8
rolando is on a distinguished road
Hi,
can anyone give me the references of the following turbulence models?
-LienCubicKELowRe
-LienLeschzinerLowRe

The nomenclature of the models in the common literature might do as well.

Thanks

Rolando
rolando is offline   Reply With Quote

Old   October 4, 2007, 11:39
Default Hey Rolando: Check the link
  #10
Member
 
Ning Yang
Join Date: Mar 2009
Location: University Park, PA, USA
Posts: 85
Rep Power: 8
nzy102 is on a distinguished road
Hey Rolando:

Check the link below:

http://www.cfd-online.com/cgi-bin/Op...cus/discus.cgi

Hope this will help.
nzy102 is offline   Reply With Quote

Old   October 4, 2007, 11:51
Default Hi Ning, something doesnīt wo
  #11
Member
 
Rolando Maier
Join Date: Mar 2009
Posts: 89
Rep Power: 8
rolando is on a distinguished road
Hi Ning,
something doesnīt work with the link you posted.
Donīt copy paste the URL. Try to right click on the yellow icon in the header line of the message (beside the blue arrows) and copy the link. This should word.

Could you please try it again?

Rolando
rolando is offline   Reply With Quote

Old   October 4, 2007, 12:20
Default Do a search for liencubic and
  #12
Member
 
Ning Yang
Join Date: Mar 2009
Location: University Park, PA, USA
Posts: 85
Rep Power: 8
nzy102 is on a distinguished road
Do a search for liencubic and you should be able to find my post.

Ning
nzy102 is offline   Reply With Quote

Old   October 4, 2007, 13:34
Default Thanks Ning Rolando
  #13
Member
 
Rolando Maier
Join Date: Mar 2009
Posts: 89
Rep Power: 8
rolando is on a distinguished road
Thanks Ning

Rolando
rolando is offline   Reply With Quote

Old   September 21, 2008, 15:13
Default Sorry for refreshing this old
  #14
Senior Member
 
BastiL
Join Date: Mar 2009
Posts: 471
Rep Power: 11
bastil is on a distinguished road
Sorry for refreshing this old post. I am wondering if OF has some kind of "blending" between Low- and Hi-Re formulations for turbulence as comercial codes have (all yplus wall threament in ccm+, hybrid wall function in STAR-CD or enhanced wall threadment in Fluent). I have not come over something like that so far.
bastil is offline   Reply With Quote

Old   September 22, 2008, 07:25
Default Hi Bastil, I am trying to i
  #15
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 10
braennstroem is on a distinguished road
Hi Bastil,

I am trying to implement a 'compound wall treatment' together with a low-Re turbulence model. I still got some trouble implementing it (http://www.cfd-online.com/OpenFOAM_D...tml?1219326882). Maybe it is a good case to take a look on at the 'Stammtisch' :-)

Fabian
braennstroem is offline   Reply With Quote

Old   August 9, 2010, 05:42
Default
  #16
Senior Member
 
Sandy Lee
Join Date: Mar 2009
Posts: 207
Rep Power: 9
sandy is on a distinguished road
Quote:
Originally Posted by braennstroem View Post
Hi Bastil,

I am trying to implement a 'compound wall treatment' together with a low-Re turbulence model. I still got some trouble implementing it (http://www.cfd-online.com/OpenFOAM_D...tml?1219326882). Maybe it is a good case to take a look on at the 'Stammtisch' :-)

Fabian
Hi Fabian, I am interesting in this kind of blending wall fuction too. What about your work for it? Did you finish it? I am also wondering why there are not V2f-like turbulence models with the "compound wall treatment" in OF.
sandy is offline   Reply With Quote

Old   August 11, 2010, 13:57
Default
  #17
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 10
braennstroem is on a distinguished road
I actually did not work von the v2f-model anymore as it did not converge for all my hvac test cases except for some 2D/3D diffuser cases. Did you have more success with the v2f-model and for which cases? I did some different approaches for the SST model, but never got as good results as Luca with his kOmega98-model...
braennstroem is offline   Reply With Quote

Old   February 4, 2011, 04:51
Default
  #18
New Member
 
Join Date: Nov 2009
Location: Germany
Posts: 8
Rep Power: 7
DanielPT is on a distinguished road
Hi,

my problem is an internal flow in a diffuser with Re_inlet=13000. My y+ is below 1, so I want to use LaunderSharmaKE as lowRe model.
Is it right to set k and epsilon to 0 at walls (at y=0) for this k-epsilon model?

Daniel
DanielPT is offline   Reply With Quote

Old   February 4, 2011, 07:19
Default
  #19
Senior Member
 
Olivier
Join Date: Jun 2009
Location: France, grenoble
Posts: 240
Rep Power: 9
olivierG is on a distinguished road
Short answer: no
(see previous post: do not use 0 but 1e-10 to avoid infinite value)
zerogradient may also work

regards,
olivier
olivierG is offline   Reply With Quote

Old   February 4, 2011, 07:52
Default
  #20
New Member
 
Join Date: Nov 2009
Location: Germany
Posts: 8
Rep Power: 7
DanielPT is on a distinguished road
Ah ok, thanks a lot Oliver! I have overlooked the previous post.

Regards
Daniel
DanielPT is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
RANS Turbulence Model John Haynes Main CFD Forum 0 January 16, 2009 17:17
UDF for Turbulence Stresses with RANS two-eq model Amr FLUENT 0 May 6, 2008 11:05
RANS vs.LES turbulence model usker CD-adapco 1 April 3, 2008 18:38
Rankings of RANS based Turbulence Models Abhijit Tilak Main CFD Forum 0 September 10, 2004 12:10
flow calculations with RANS 2eq models Andreas Abdon Main CFD Forum 3 March 8, 2000 07:09


All times are GMT -4. The time now is 15:51.