Law of the wall
= Law of the wall
{title2=$U/u_*=\kappa^{-1}\log(z/z_0)$}
{wiki}
In a neutral turbulent constant-stress region, the stress velocity and wall distance give mean shear $U_z=u_*/(\kappa z)$. Its logarithmic integral uses the <roughness length>. The law applies outside the inner sublayer and below the outer boundary-layer scale, not all the way to a smooth wall.