First grid point in boundary layer, y+
 

Hey all,

I am going to perform a LES of turbulent channel flow.

would anybody please give me some idea of how fine the grid need to be. Somebody says you should resolve the boundary layer with at least 10 points across it, and with the first grid point at a position of approximately y+ = 1.

Given the definition of y+, how would you evaluate the frictional velocity (u*) which itself needs the shear stress at the wall? :confused:

Thanks.
Sinas