CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   Is Y+ depends on the tubulence model? (http://www.cfd-online.com/Forums/main/92266-y-depends-tubulence-model.html)

krishnag2002 September 8, 2011 07:23

Is Y+ depends on the tubulence model?
 
If we use different turbulence models, the target Y+ will change accordingly?

cfd_newbie September 8, 2011 07:52

Quote:

Originally Posted by krishnag2002 (Post 323395)
If we use different turbulence models, the target Y+ will change accordingly?

Does you question mean -
"If you use different turbulence models we should target different Y+ while making grids ?"

krishnag2002 September 8, 2011 09:18

Yes Thanks in Advance

cfd_newbie September 8, 2011 23:36

These 3 links might be useful -
http://www.cfd-online.com/Forums/mai...ga-models.html
http://www.cfd-online.com/Wiki/RANS-...bulence_models
http://www.kxcad.net/STAR-CCM/online...ulence-15.html

mettler September 9, 2011 08:26

yes, it does

for the turbulence model chosen, a preferable range of Y+ must be obtained to be considered valid the analysis. What drives this range will be the size of the first cell adiacent to the wall.

Far September 12, 2011 15:44

for example yplus 30 or greater for K epsilon based models and y+1 ~ for the SST, BSL and SA type models. It is the preferable approach.

although we can extend the K epsilon model to yplus = 1 range by using the special damping functions as implemented in the Fluent

similarly SST model can be used with the yplus = 30 mesh


P.S: Yplus = 30 or greater implies we are not solving the viscous sub-layer (yplus 2 or less) and buffer layer (in between 2 and 30). It is also called wall function approach

Yplus = 1 implies we are resolving the viscous sub layer. It is necessary to use the yplus = 1 type mesh if flow is dominated by the separation and reattachment where wall function ceases to be valid

In commercial CFD codes after Yplus = 11.06 wall function approach is activated and below this viscous sub layer approach is used

also check this link http://www.cfd-online.com/Forums/cfx...machinery.html

krishnag2002 September 13, 2011 02:06

thanks for your information. now I have some idea about Y+


All times are GMT -4. The time now is 18:39.