Mesh problem in Ansys Turbogrid

[mahdien]

in ansys turbogrid i faced a setting that couldn't find out how it works and couldn't find an appropriate description for that.
Near Wall Element Size specification in mesh data object that has 3 methods(1-absolute 2-y+ 3-normalize)
i upload an image from software
if someone know anything about these please help me

thanks

 

[bigfooted]

I'm not familiar with turbogrid, but I'd say that for 1-absolute you give the size of the first cell at the wall in absolute numbers, e.g. 0.001 m.
if it is 2-y+, your cell size will be such that you obtain a certain y+ value at the wall, e.g. y+=1 for completely resolved wall or y+=30 if you are using turbulence wall functions. 3-normalized, you probably give a relative value based on some length scale, so if it is a pipe with a typical length scale of 2 m, then 0.001 will mean a 0.002 m cell size at the wall.
Having a mesh with a certain y+ value is preferred, but you need the local velocity for that, so the actual solution of the flow problem. I'm not sure how turbogrid knows how to do this.