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Old   March 13, 2006, 16:11
Default Dear all In my case of chan
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tadashi
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Dear all

In my case of channelOodles, the result of velocity seems laminar profile(parabolic profile) even at turbulent condition.
I think something my setup is wrong, but I can't find it.
Please help anybody!

Values of my case model are below.

Re number=30000.

turbulenceProperties are
LESmodel: Smagorinsky
delta : vanDriest

Values of Ubar and nu are written on transportProperties file.

Y+ values are below 10.

initial value of k is zero.
inlet outlet conditions are cyclic.
Other conditions are refered from tutorial sample.

Best regards

Tadashi
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Old   March 13, 2006, 17:42
Default You should not start with init
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Hrvoje Jasak
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You should not start with initial k = 0. Estimate uPrime to several percent of uBar and do

k = 3/2 uPrime^2

as the initial guess of k.

Hrv
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Old   March 14, 2006, 08:52
Default Thank you very much Hrv. I wi
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Thank you very much Hrv.
I will try again with your advice.

Tadashi
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Old   March 14, 2006, 09:32
Default What is your initial value of
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Eugene de Villiers
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What is your initial value of U?

The case will take ages to go turbulent from a uniform velocity unless you give it a push.
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Old   March 14, 2006, 10:12
Default Hi Eugene Initial value of
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tadashi
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Hi Eugene

Initial value of U is as same as value of Ubar for uniform, and I could get turbulent condition with my case. But the result of mean velocity profile is quite different from that of RANS result.

Is there any other value that I must check?

Tadashi
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Old   March 14, 2006, 11:57
Default Hmm, above you said your U pro
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Eugene de Villiers
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Hmm, above you said your U profile was parabolic. The only way for that to happen is for the resolved flow to be laminar (at least in my experience).

Could you post a picture of the instantaneous U and k in the channel?
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Old   March 14, 2006, 12:52
Default Please refer as below. U \
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tadashi
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Please refer as below.

U
\image(/home/tadashi/temp/LES_U.jpg)
k
\image(/home/tadashi/temp/LES_k.jpg)
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Old   March 14, 2006, 13:48
Default Sorry, I am not good at these
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tadashi
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Sorry, I am not good at these kinds.

U

k

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Old   March 24, 2006, 14:12
Default Dear Eugene Sorry, I couldn
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tadashi
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Dear Eugene

Sorry, I couldn't upload pics.
But I thought that the problem is cyclic boundary condition will just loose kinetic energy every iterations.
Finaly, flow will become laminar.
How to give kinetic energy to flow every iterations?
Or is my understanding wrong?
Thanks.
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Old   March 25, 2006, 10:00
Default channelOodles already takes ca
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Eugene de Villiers
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channelOodles already takes care of this via a mean pressure gradient that is adjusted to maintain the target mean velocity, Ubar, that is set in the transportProperties dictionary. Of course running normal oodels on a periodic flow will cause it to wind down.

Check the formatting section of the forum on how to upload pictures.
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