...
Problem Setup > Reference Values
Select inlet inlet under Compute Fromto tell FLUENT to use values at the pipe inlet for the reference values. Check that the reference value for density is 1 kg/m3, velocity is 1 m/s, and coefficient of viscosity is 2e-5 kg/m-s as given in the Problem Specification.These reference values will be used to non-dimensionalize the distance of the cell center from the wall to obtain the corresponding y+ values.
Let's plot y+ values for wall-adjacent cells to check how it compares with the recommendation mentioned above.
...