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Recomended value for y+?

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Old   September 20, 2004, 10:07
Default Recomended value for y+?
  #1
Joe
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Looking for the y+ distance from the wall to the wall-adjacent cell when using the Non-Equilibrium Wall functions?

Thank you /Joe
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Old   September 20, 2004, 21:34
Default Re: Recomended value for y+?
  #2
carlos ortiz
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I would recommend between 1 and 5 for mesh adaption.
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Old   September 21, 2004, 02:01
Default Re: Recomended value for y+?
  #3
anindya
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I believe you have the same rules as for standard wall functions, i.e. y+ > 30. Please check Fluent manual (chapter 10 on turbulence modeling)
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Old   October 3, 2004, 10:07
Default Re: Recomended value for y+?
  #4
ap
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If you use standard or non-equilibrium wall-function, you need to have 30 < y+ < 60.

Values of y+ close to 1 are required by the enhanced wall treatment, but are not acceptable for wall-functions.

Hi

ap
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Old   October 3, 2004, 10:08
Default Re: Recomended value for y+?
  #5
ap
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This is not valid for wall functions, but for the enhanced wall treatment.

Hi

ap
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Old   October 12, 2004, 16:28
Default Re: Recomended value for y+?
  #6
chenjiansheng
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Hello, ap

Why you always say Y+ is between(30,60)? As I know near 30 is ok! someone always use >11.

Can you give some references?

thanks
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Old   October 12, 2004, 17:21
Default Re: Recomended value for y+?
  #7
ap
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A good reference is Wilcox's book:

D. C. Wilcox. Turbulence Modeling for CFD. DCW Industries, Inc., La Canada, California, 1998.

For y+ < 11.225 FLUENT uses the linear law, while it switches to the log law for greater values of y+, which, however, is proven to be valid only for y+ about in the range 30 < y+ < 60. The more you go out of this range, the worst results you should expect, but keep in mind these are empirical results (all wall functions are based on empirical results).

You're right, a value around 30 is ok, it's close to the range of validity.

Hi

ap
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