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Low-Reynolds k-eps models

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Old   February 17, 2011, 22:46
Default Low-Reynolds k-eps models
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Hi everybody,

Anybody knows if it is possible to use low-Reynolds k-eps models in Fluent?
To clarify, in low_Re models the coefficients C_mu, C_eps1 and C_eps2 are modified based on flow characteristics or the distance from wall (different approaches in different models), and two source terms are also added to k and eps transport equations.
To summarize, I wanna know if it is possible to employ user defined coefficients rather than constant ones in Fluent and add new terms to the turbulence transport equations.
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Old   February 18, 2011, 01:48
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Hi,

you can change the constants used for the k-e model using a journal file if you want after each time step or iterations if you want. To get the basic framework you can record a journal file where manually change the constats. Using this as a reference you can add your own functions to the code to change it between time steps.

I do not think that you can add source terms to the existing equations though.

If it is a low- Re flow you could also use the k-w model.
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Old   February 18, 2011, 21:48
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Thank you for your help.
Could you please give me more explanation about journal files? or tell me where can I obtain more info.
In fact, I should decide whether Fluent is capable enough for my problem or I better proceed to an in-house code. It is actually a determining step for my PhD thesis.
How much using a journal file can increase computational cost? (I mean solution time)
I should model a rather complicated mixed convection turbulence flow and I need to examine different turbulence models so it is important for me to have enough freedom in using software.
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Old   February 18, 2011, 22:05
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I should add that the coefficients are functions of position too, so it is not enough to change them in each time step but in each cell.
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