However, the predicted trend of Lh with the Rein number is
similar to the correlation calculation. If the constant of 4.4 in the
correlation is increased to 5.8, that is, x=D ¼ 5:8Re0:6 (red line), the
predicted results are in good agreement with the correlation
calculations, as clearly demonstrated in this figure.
Fig. 2 also reveals that the fully-developed friction factor (fw,N) is
predicted to decrease with increasing Rein number. Fig. 4 compares
the predicted dependence of fw,N on the Rein number (dots) with
that obtained from the Blasius correlation [28] (dash) and the
Moody diagram [29] (line). The Blasius correlation is well applied in
the round tube with the Rein > 2300 and has the following form: