[hamidciv]

hi to all
i read help of cfx about near wall modeling, As it was written, two way exist for modeling flow near the wall:
1-wall function approach that using of scalable wall function that used for all models based on epsilon equation.

2- The Low-Reynolds-Number method that is suitable for models based on omega equation, in fact it has automatic near wall treatment in order to reduce Requirements of resolution.

whether yplus for models are based on epsilon equation cant located in viscous sublayer? whether it induce To need to yplus< 0.2 in low reynolds number?
unfortunately i dont find specific values for yplus for variety of turbulence models and only discussed about low-Reynolds number k-epsilon & k-w in help cfx, i find your mentions about this in previous topic as following:
SST can handle any y+.
k-e should be >11
k-omega should be <1
RSM should be >11 if using wall functions or anything if automatic.
The question that came to me is that:
as your mentioned , sst can handle with any yplus, in my simulation y+ value is too large, But I did was sensitivity study in mesh, whether really amount does not matter and What is the reason it?
There is no specific limit?
my impression is that it Due to the use of automatic near wall treatment.
i opologize for long discussion

thanks a lot for any comment
kind regards
hamid

[ghorrocks]

whether yplus for models are based on epsilon equation cant located in viscous sublayer?

I don't quite understand this question, but I will guess. Epsilon based turbulence models are undefined at the walls. So you need to do something at the walls for a boundary condition, and wall functions are the normal approach. Omega based turbulence models are defined at the walls, so they can be integrated directly to the wall with no special treatment required.

The maximum value allowable for y+ comes down to a mesh size sensitivity, and the error you are happy to have in the simulation.

[hamidciv]

hi dear glenn
as your mentioned, your guess about my question is correct and I mean it was.
thanks a lot