||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