Question

Friction factor for fluid flow in pipe does not depend upon the A. pipe length. B. pipe roughness. C. fluid density & viscosity. D. mass flow rate of fluid.

Answer 1

C. fluid density & viscosity

Step-by-step explanation:

In 1850, Darcy-Weisbach experimentally deduced an equation to calculate shear losses ("friction"), in a tube with permanent flow and constant diameter:

hf = (f x L x V^2) / (D x 2g)

where:

hf: shear losses

f: shear loss factor (pipe roughness)

g: gravity acceleration

D: tube diameter

L: tube length

V: fluid average speed in the tube

To calculate the loss factor “f” in the Poiseuille laminar region, he proposed in 1846 the following equation:

f = 64 / Re

Where:

Re: Reynolds number

The influence of the parameters on f is quantitatively different according to the characteristics of the current.

In any straight pipeline that transports a liquid at a certain temperature, there is a critical speed below which the regimen is laminar. This critical value that marks the transition between the two regimes, laminar and turbulent, corresponds to a Re = 2300, although in practice, between 2000 and 4000 the situation is quite inaccurate. Thus:

Re <2000: laminar regimen

2000 <Re <4000: critical or transition zone

Re> 4000: turbulent regime