Question

For a smooth conduit, which of the following is the value of friction factor (f) for laminar and turbulent flow respectively?

(a) 10/Re, 0.0791(Re)^-0.25

(b) 16/Re, 0.0791(Re)^-0.25

(c) 10/Re, 0.0771(Re)^-0.25

(d) 16/Re, 0.0171(Re)^-0.25

I have been asked this question by my college director while I was bunking the class.

This key question is from Effects of Friction and Velocity Distribution in chapter Pouring – Gating Design, Melting Furnaces, Melting and Casting Quality of Casting-Forming-Welding I

Answer 1

Correct choice is (b) 16/Re, 0.0791(Re)^-0.25

The explanation: For a smooth conduit, the value of f is given by the equations

f = 16/Re for laminar flow (Re < 2000),

f = 0.0791(Re)^-0.25 for turbulent flow (Re > 2000),

Where, Re is Reynolds number.