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-   -   is there a yStarRAS tool? (http://www.cfd-online.com/Forums/openfoam-post-processing/119079-there-ystarras-tool.html)

immortality June 9, 2013 13:13

is there a yStarRAS tool?
 
Hi
is there a tool for y* like y+?

wyldckat June 9, 2013 15:23

Hi Ehsan,

AFAIK, there isn't one.

Uhm... didn't you make this bug report: http://www.openfoam.org/mantisbt/view.php?id=835
Here's a very old bug report also on this topic: http://www.cfd-online.com/Forums/ope...-vs-ystar.html - but the answers you got on your bug report was better.

In the mean time, I also found this: http://www.cfd-online.com/Forums/ope...tml#post424723 - post #4 - which was in response to a similar question of yours from a month ago.


So the very big question is: which "yStar" are you looking for?


The only references I found in OpenFOAM's own source code was in these files:
Code:

src/turbulenceModels/incompressible/RAS/LienLeschzinerLowRe/LienLeschzinerLowRe.C
src/turbulenceModels/incompressible/RAS/LienCubicKELowRe/LienCubicKELowRe.C

Both calculate it this way:
Code:

yStar_ = sqrt(k_)*y_/nu() + SMALL
Best regards,
Bruno

immortality June 9, 2013 16:48

thanks.I wanted to be confident about this subject.
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well then yPlusRAS acts as a y* function that is suitable in high-Re turbulent simulation(when the first cell center is in logarithmic region of turbulent boundary layer)
but yPlus tool that is created by cfd-online users is used when we have low-Re meshes(when first cell center is in laminar-sub layer region of turbulent boundary layer)
:)


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