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February 15, 2010, 04:57 |
Initial condition
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#1 |
New Member
Join Date: Apr 2009
Posts: 14
Rep Power: 17 |
Hi to everyone!
I would like to create a turbulent initial condition for my channel flow simulation.. but i don't know how to do it! I used foamCalc randomise 0.2 U for creating a perturbation inside the velocity field.. but after few time-steps (10= 1 sec), the flow became laminar again.. So i try to perturb the flow every 10 time step.. but now i'm at 20 sec and if i don't perturb the flow, it returns laminar again (after 30 time steps= 3 second)... what i have to do? thx |
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February 15, 2010, 12:54 |
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#2 |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
__________________
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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June 23, 2011, 18:24 |
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#3 |
Senior Member
Tarak
Join Date: Aug 2010
Location: State College, PA
Posts: 111
Rep Power: 15 |
Hii Alberto,
Can you please let me know the best way to get an initial perturbed field for starting a LES simulation? Just like perturbU, which is for channel flow, I need to know a generalized way to get the preturbations. Presently I am using the turbulentinlet boundary condition, with 2% fluctuation. Is it a good way to generate instabilities? Thanks, Tarak |
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June 23, 2011, 18:41 |
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#4 | |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Quote:
The initialisation depends on the case you are considering. If you have an inlet, and have detailed information on the flow conditions there, you might want to consider synthetic turbulence BC's (you'll have to implement them). If you are interested, you should check the literature on the topic. Some OF users were working on that too, so the Turbulence SIG (see wiki) might be of help. Best,
__________________
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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