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TurbulentInlet BC

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Old   September 5, 2006, 05:09
Default I want to use the 'turbulentIn
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chris book
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I want to use the 'turbulentInlet' boundary condition. As far as I can see the use only inputs a fluctuation scale but what about the integral length scale or other appropiate scales because the flucation scale alone do not define a turublent inlet.

Ok I know it is anyway no real turbulent inlet because there is no turbulence strcuture etc.

Additionally, I was wondering what I have to set for k and epsilon at this turbulent boundary (using high Re k-epsilon turb model)?
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Old   September 5, 2006, 11:15
Default Is there nobody who is able or
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Is there nobody who is able or want to answer my question?
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Old   September 5, 2006, 12:21
Default Hi, I think that that turbu
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Pierre Le Fur
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Hi,

I think that that turbulentInlet is to be used for LES/DNS, not RANS. It just produces a random noise at the inlet of given magnitude, which anyway is most lileky to be dissipated quickly.

For RANS, if you use K-Eps, just use fixed value boundary conditions and set k and Eps to what you like.
You can use something like
K_inlet = 3/2 (Uref*T)^2 and Eps = Cmu*k^(3/2)/L
where T is tubulence intensity (10% for example) and L is a turbulent lengthscale.

Hope this helps
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Old   September 20, 2006, 13:50
Default Excuse me for the stupid quest
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Daniel Mills
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Excuse me for the stupid question. I did not know you could actually set BC's like this. What would an example of the actual inlet BC be for k and epsilon?
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Old   September 9, 2013, 00:32
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chris

if you have found answer to your query, can you please let me know. I want to use turbulentInlet BC.

regards
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Old   March 27, 2014, 09:35
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Hi,

I am searching what does "fluctuationScale" in turbulentInlet BC mean?

If I set it 0.01, for example? What is this value signify?

Thanks in advance,

vut
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