SIMPLE algorithm and keps turbulence model
I'm using SIMPLEbased control volume method and Keps 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 
a suggestion
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 !

Re: a suggestion
If y+ is getting small this can get tricky indeed, as you may not be respecting your model's assumptions. In Aero applications LowRe kE models are much more adapted as well as Shear Stress Transport kOmega type models where you integrate to the walls.

Re: a suggestion
Dear Abhi
What's the meaning of G in your suggestion? YANG 
Re: a suggestion
Hi, Abhi
What's the lower limit of n+ for kepsilon model near the solid wall? Thanks YANG 
Re: a suggestion
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... 
Re: a suggestion
Dear Holidays
Thanks a lot for you patient help. YANG 
Re: a suggestion
"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.

Re: a suggestion
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...

Re: a suggestion
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

Re: SIMPLE algorithm and keps turbulence model
i am using the TEACHT code which uses the SIMPLE algorithm and KE model and i want to modify it to solve unsteady problem what type of code ur using and what do u think of TEACHT and could the modification be easily accomplished


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