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LES of Non-Premixed Combustion in CFX??

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Old   February 3, 2008, 09:14
Default LES of Non-Premixed Combustion in CFX??
  #1
Manu
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Hi Robin and Glenn, Just curious to know why i cant combine LES Samagorisky Model and Eddy Dissipation Model for a non premixed combustion problem in CFX? Is CFX unable to do LES for such problem? However support says SAS is capable enough to give results like LES. But i am not satisfied. Can you please throw some light on it. Thanks in advance.

Manu
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Old   February 3, 2008, 17:35
Default Re: LES of Non-Premixed Combustion in CFX??
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Glenn Horrocks
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Hi,

I have no experience in using the Eddy Dissipation model in LES, but I can't see why you can't use it with LES. What is telling you that you cannot use it?

Glenn Horrocks
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Old   February 4, 2008, 04:09
Default Re: LES of Non-Premixed Combustion in CFX??
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Manu
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Hi Glenn, When you select both( EDM and LES) of them and press ok. After that if you reopen to see whether they are there or not i always find k-e has replaced the LES Samagosrinsky model. This is what the problem is. regards Kirti

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Old   February 4, 2008, 17:30
Default Re: LES of Non-Premixed Combustion in CFX??
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Glenn Horrocks
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Hi,

I would talk to CFX support about this. It may be a bug in CFX-Pre. You can tell the solver to use EDM and LES via the CCL anyway if you want to over-ride CFX-Pre.

Regards, Glenn Horrocks
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Old   February 22, 2008, 12:18
Default Re: LES of Non-Premixed Combustion in CFX??
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Rumors
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In their standard formulations these models are not combineable. The reason is not a bug in CFX but the theory of both models. Have a look at the theory manual of CFX or the literature (famous old paper of Spalding). The EDM reaction rate depends on turbulent kinetic energy and its dissipation. How do you define these quantities in LES?

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Old   February 25, 2008, 17:34
Default Re: LES of Non-Premixed Combustion in CFX??
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Glenn Horrocks
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Hi,

Good point!

Glenn Horrocks
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