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September 1, 2010, 12:55 |
max courant/courant...velocity spikes?
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#1 |
New Member
Matt James
Join Date: Jun 2010
Location: Marinette,WI, USA
Posts: 25
Rep Power: 15 |
Hi all,
I'm running a turbulent half-channel flow (dynSmag). I'm wondering why the max courant number is being reported in the neighborhood of 10-12 while the mean courant is around 0.3, where i calculated it based on expected mean flow. Where might these wild velocity fluctuations be coming from? Thanks very much for any help! |
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September 17, 2010, 00:59 |
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#2 |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Have you very refined cells somewhere in your domain?
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 17, 2010, 13:08 |
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#3 |
New Member
Matt James
Join Date: Jun 2010
Location: Marinette,WI, USA
Posts: 25
Rep Power: 15 |
Ah, yes. I have some near wall refinement but only in the wall normal direction. Eddy generation and therefore v and w velocities occurring I suppose?
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September 21, 2010, 15:06 |
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#4 |
Senior Member
Steven van Haren
Join Date: Aug 2010
Location: The Netherlands
Posts: 149
Rep Power: 15 |
Have the same "problem" in my channel flow LES/DNS.
If you are interested you can use the Co utility to determine where the high Courant number appears. |
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September 24, 2010, 03:32 |
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#5 | |
Senior Member
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Hello,
i have two questions. Quote:
Is it possible to tell more about Co utility? |
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September 24, 2010, 04:20 |
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#6 |
Senior Member
Steven van Haren
Join Date: Aug 2010
Location: The Netherlands
Posts: 149
Rep Power: 15 |
Which solver are u using? I get mean and max Co in my terminal window using channelFoam/channelOodles.
Co utility should be in your openfoam folder. Just use Co -help to see how it works. |
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September 24, 2010, 05:44 |
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#7 |
Senior Member
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i use pisoFoam. i want solve a rearward facing step with RAS and LES. my problem is i don't know how much can courant be large in solving process. do you know about it?
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September 24, 2010, 06:26 |
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#8 |
Senior Member
Steven van Haren
Join Date: Aug 2010
Location: The Netherlands
Posts: 149
Rep Power: 15 |
RAS, no idea
LES, max CFL ~ 0.5 |
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