Whether a fluid is experiencing laminar or transitional fluid

flow can be determined by its Reynolds number, which is discussed below.

However, transitional flow can possess many flow rates and mannerism due its

differing frictional energy whilst flowing therefore with separate equations to

predict its fluid flow behaviour.

A typical piping system involves; various diameter pipes

connected by various fittings/elbows, which route the fluid, valves to control

flow rate, pumps to pressurize the fluid. Fluid flow, especially liquids, are

generally transported in circular pipes as they can endure great pressure variances,

without substantial distortion. The loss of pressure/energy (for example, in

the forms of heat or sound) in a fluid, through a pipe, is due to the required

energy to overcome the viscous or frictional forces exerted by the walls of the

pipe on the moving fluid (Uio.no,

n.d.). Energy losses also occur due to fluid flowing through

fittings (valves, elbows, contractions and expansion). The pressure losses in

pipes are known as head losses, derived from Bernoulli’s equation. Head losses

are categorized into minor and major head losses. Minor energy head losses are

due to the bends and valves present within the system whereas, energy losses

due to the frictional resistance acting against the flow of the fluid, are

defined as major head losses; together equating to the total head loss. (Kabir, 2014)

Major head losses are

calculated using the Darcy-Weishbach equation, equation 1:

The dimensionless quantity, the Darcy frictional factor, is

used in the Darcy-Weishbach equation, equation 2. It is used as a description

of the frictional losses in pipe flow (Nuclear Power, n.d.):The friction factor, f is dependent on the flow’s Reynolds

number and on the pipes degree of roughness on the pipe’s inner surface (. Reynold’s number is dimensionless and is the ratio of the fluids’

inertia force to the fluids viscosity force, and can be found using the

equation 3:

Reynolds number can be used to describe the behavior of the flow. The

flow can be either laminar or turbulent depending on whether the Reynolds

number is above or below a critical value. The critical Reynolds value for pipe

flow is around 2000. Where above critical value is a turbulent flow and below

is laminar (both flows can be observed when the value is close to the critical

value). Experimental evidence has proven and concluded that the frictional

factor is dependent on the Reynolds number as well as the degree of roughness. As

outlined on the moody chart (Engineeringtoolbox.com, n.d.).

As a rule, the flow is:

i)

Laminar when Reynolds number is <2300.
ii)
Turbulent when the reynolds number is 2300