Derive the formula Friction Factor in Terms of Reynolds Number for Smooth Pipes for turbulent flow and for rough pipe, to show the following Eqns. (1/vf)=1.74 In (Revf) -0.391 Hint: For the purposes of obtaining the total flow rate, and hence the mean velocity, the logarithmic profile vz+ = A + B Iny+ can be assumed to hold over the whole pipe, because the laminar sublayer is so thin and contributes virtually nothing to the flow.