[immortality]

I have heard from someone that in compressible cases Y* should be considered not Y+ for turbulence.
for example as he said in low-Re method y*<1 is the condition not y+<1.
have anyone heard something about somewhere or have any experiments?
thanks.

[wyldckat]

Hi Ehsan,

Since you asked me for my point of view on this (caution: very limited point of view, since I'm not an expert in CFD!), here goes:

All I can find on this topic is from a very old Fluent manual I found online using Google, is that Fluent uses the:

laws-of-the-wall for mean velocity and temperature are based on the wall unit, y*

which is basically based on this: http://www.cfd-online.com/Wiki/Two_e...wall_functions

So, what I can figure out is that the class of the wall function itself will calculate the local y+ or y*, depending on the implementation the authors followed.
As for the indicative value y+ or y*, it depends on:

• the wall function itself;
• and on whether you want it to handle the "viscous" or the "log" zone. (for other readers, see this recent thread: http://www.cfd-online.com/Forums/ope...tml#post432933 post #4)

Best regards,
Bruno