Hi all,
I have some doubts,
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 |
Choose
LienCubicKELowRe,
Lie
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. |
You're probably better off wit
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 |
First, thank you very much for
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 |
For compressible flows, we've
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 |
sorry for the confusion in the
sorry for the confusion in the last phrase..
your answer is enough for my doubt. Best regards Luca |
I am trying to use Launder-Sha
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? |
In any CFD software, avoid as
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 |
Hi,
can anyone give me the re
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 |
Hey Rolando:
Check the link
Hey Rolando:
Check the link below: http://www.cfd-online.com/cgi-bin/Op...cus/discus.cgi Hope this will help. |
Hi Ning,
something doesnīt wo
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 |
Do a search for liencubic and
Do a search for liencubic and you should be able to find my post.
Ning |
Thanks Ning
Rolando
Thanks Ning
Rolando |
Sorry for refreshing this old
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.
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Hi Bastil,
I am trying to i
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 |
Quote:
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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...
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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 |
Short answer: no
(see previous post: do not use 0 but 1e-10 to avoid infinite value) zerogradient may also work regards, olivier |
Ah ok, thanks a lot Oliver! I have overlooked the previous post.
Regards Daniel |
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