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February 1, 2011, 16:07 |
perturbation in channelFoam?
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#1 |
Member
Charlie
Join Date: Dec 2010
Location: USA
Posts: 85
Rep Power: 15 |
I've just run the channelFoam using dynSmagorinsky model.
I just run the original case in tutorials, and found that the result seems to be more like laminar, which gives a Poiseuille flow. Maybe that's because I didn't define a perturbation in channelFoam, in k file in 0 folder, I can see that it's uniform 0. Can I just change it to be nonzero? Also the boundary type is fixed value of 0, can I change it to what's in RAS, i.e. kqRwallfunction? In the attachment, the dot stand for the classic profile of turbulence. 2.5log(y+) +5.5, the solid line stand for the result without defining perturbation. Does anyone have a similar experience? How can I set up the cse correctly to reproduce the log law? Thank you! |
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February 2, 2011, 16:42 |
Know how to add perturbation!
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#2 |
Member
Charlie
Join Date: Dec 2010
Location: USA
Posts: 85
Rep Power: 15 |
Forget it, I figured out that perturbU can do that, hopefully, I can post some results after a while.
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November 2, 2011, 12:58 |
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#3 |
New Member
Getnet
Join Date: Aug 2011
Location: LSU
Posts: 20
Rep Power: 15 |
I have the same problem. My channel flow is laminar and I am getting a problem when I run LES. Do you get any idea how to get turbulent flow in your channel simulation?
Thanks Last edited by aka; November 23, 2011 at 15:49. |
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November 2, 2011, 14:29 |
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#4 | |
Member
Charlie
Join Date: Dec 2010
Location: USA
Posts: 85
Rep Power: 15 |
you could use perturbU to generate perturbations based on the laminar solution, this will make your simulation to fully turbulent faster.
Basically, the perturbation is added following a Gauss normal distribution, you can define the magnitude of the perturbation, and you may need a few tries. you are also trying to implement LES in sediment transport? which model do you want to use? Quote:
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November 2, 2011, 15:10 |
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#5 |
New Member
Getnet
Join Date: Aug 2011
Location: LSU
Posts: 20
Rep Power: 15 |
Thanks. Yes I am trying to implement a sediment transport model.
Last edited by aka; November 23, 2011 at 15:52. |
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November 2, 2011, 16:36 |
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#6 |
New Member
Getnet
Join Date: Aug 2011
Location: LSU
Posts: 20
Rep Power: 15 |
one quick question: perturbU needs 'retau' in transport properties. Is there any thing else I have to put in the 'U' or 'k' files inside '0' folder?
Thanks |
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