Question

Which among the following is the formula for friction factor(f)?

(a) f = 0.079*Re^0.25

(b) f = 0.079/Re^0.25

(c) f = 0.079/Re^0.5

(d) f = 0.079*Re^0.5

I got this question during an interview.

My doubt is from Loss of Head due to Friction in Viscous Flow topic in chapter Viscous Flow & Turbulent Flow of Fluid Mechanics

Answer 1

The correct option is (b) f = 0.079/Re^0.25

The best explanation: To calculate the friction factor of a fluid, we use the Blasius equation. This equation is accurate for values within 5% having Reynolds number less than 10^5. (Blasius equation: f= 0.079/Re^0.25)