Air ( ρ=1.23kg/m3, µ=1.79x10-5 N-s/m2) flows in 0.2m long pipe of D= 0.005m, V=40m/s. Given the roughness of the pipe is ε=0.0015mm.
The friction factor (f) is given by:
1/sqrt(f)+2log10[(E/3.5D)+2.5/(re)sqrt(f)=0
re=ρVD/µ
ρ=density of fluid
µ=viscosity of fluid