Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

The Darcy friction factor f for laminar flow in a circular pipe (Reynolds number less than 2320) is given by the formula.

f = 64/Re.

There is a mistake here, its not loss of head, its expression for coefficient of friction.

Fanning's coefficient of friction f = 16/Re.

Darcy's friction factor f = 64/Re.

Coefficient of friction (f) = 16/Re.

Friction factor = 64/Re.

If the value of the friction factor is 0.064, then the Darcy friction factor is plotted in the Moody diagram. Note that the nonzero digits in 0.064 are the numerator in the formula for the laminar.

Darcy friction factor: fD = 64/Re.

If the value of the friction factor is 0.016, then the Fanning friction factor is plotted in the Moody diagram. Note that the nonzero digits in 0.016 are the numerator in the formula for the laminar.

Fanning friction factor: f = 16/Re.

If friction factor is asked then 64/Re.

If coefficient of friction is asked then 16/Re.

f=16/Re is the expression for the entry length of a fully developed flow.

Its depend on the "f" value, if it is nearly equal to 0.01, it would be f.

Or if it is nearly 0.0001, it would be "4f".

4f = 64/Re.
=>f=16/Re answer.

@Bharat.

Its Only f=64/Re.

Not 4f.