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SIMPLE algorithm and k-eps turbulence model

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Old   October 14, 2002, 05:17
Default SIMPLE algorithm and k-eps turbulence model
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zqnwpu
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I'm using SIMPLE-based control volume method and K-eps model to calculate the flow fields around airfoils,but when I use much more grids or highly stretched grids near the solid surface, the computation diverges,I don't know what caused this. Can anyone help me with that? thanks!

Zhang
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Old   October 14, 2002, 06:35
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Abhi
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keep an eye on the n+ value. See whether the code diverges when n+ is < 11.63 in one of the cells? If that is the case, then derive the value of G, epsilon & wall shear stress using linear velocity profile !
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Old   October 15, 2002, 02:31
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Holidays
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If y+ is getting small this can get tricky indeed, as you may not be respecting your model's assumptions. In Aero applications Low-Re k-E models are much more adapted as well as Shear Stress Transport k-Omega type models where you integrate to the walls.
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Old   October 15, 2002, 21:46
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YANG
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Dear Abhi

What's the meaning of G in your suggestion?

YANG
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Old   October 15, 2002, 21:55
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YANG
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Hi, Abhi

What's the lower limit of n+ for k-epsilon model near the solid wall?

Thanks YANG
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Old   October 16, 2002, 02:46
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Yang,

You should read CFD textbook materials! Details about most classical models, their applications and restrictions can be found in the books by Versteeg and Malalasekera (1995) or Wilcox (1993) for a more exhaustive approach. These are only suggestions of reading; there exist a lot more. In these anyway you would find explanations on P and G terms (G is the production term due to body force in general) and a lot more...
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Old   October 16, 2002, 03:50
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YANG
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Dear Holidays

Thanks a lot for you patient help.

YANG
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Old   October 16, 2002, 06:00
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"G is the production term due to body force in general" - it originates when you go for Reynold's averaging. Look at the viscous dissipation.
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Old   October 16, 2002, 07:02
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G is of the form Gbuoy (+Grot + Gresist) with Gbuoy which can be written as -Mu_effective/(Rho*Sigma_Rho)*g*GradRho, ie a term that accounts for buoyancy and body force effects...
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Old   October 16, 2002, 08:42
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Abhi
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Was the question first coined by YANG ? Yang , give me some more inputs abt the way ur code is behaving. May be I can suggest something. READ Turbulent Flows by STEFAN POPE if u have not!!!!!!! A very very good book
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Old   October 21, 2002, 18:22
Default Re: SIMPLE algorithm and k-eps turbulence model
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ammar
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i am using the TEACH-T code which uses the SIMPLE algorithm and K-E model and i want to modify it to solve unsteady problem what type of code ur using and what do u think of TEACH-T and could the modification be easily accomplished
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Old   May 28, 2012, 04:08
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milad
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Hi,
Would you please send me the TEACH-T code.
Thanks a lot.
my email : ghorbani.mec@gmail.com
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