y+ is similar to a local Reynolds number, so its magnitude can

be expected to determine the relative importance of viscous and turbulent

processes. Different regions, or layers, in the near-wall flow are defined on the basis

of y+. In the viscous wall region y+ < 50, there is a direct effect of molecular

viscosity on the shear stress; whereas, conversely, in the outer layer y+>50 the direct effect of viscosity is negligible. Within the viscous wall region, in the viscous sublayer y+