Reynolds number formula
Reynolds number is used to check whether the flow is laminar or turbulent. It is denoted by Re. This number got by comparing inertial force with Viscous force.It is found by dividing the fluid's inertial force by its viscous force. The Reynold's number is unitless.
\[Reynolds\: number =\frac{Inital\: force}{Viscous \: force}=\frac{density \times velocity \times diameter}{viscosity} \]
\[R=\frac{\rho \vartheta L}{\mu } \]
R = Reynold's number (unitless)
ρ = the density of the fluid (kg/m3)
v = the velocity of the fluid (m/s)
L = the "characteristic length"or diameter of the fluid flow (m)
μ = the viscosity of the fluid
For a circular pipe, the characteristic length is the diameter of the pipe. The boundaries between the types of flow are:
- Laminar flow when R < 2300
- Transient flow when 2300 < R < 4000
- Turbulent flow when R > 4000
