Reynolds number (Re) is a dimensionless number that predicts flow patterns in different fluid flow situations. It is defined as:
Where:
ρ = fluid density
v = fluid velocity
L = characteristic length (e.g., diameter of a pipe)
μ = dynamic viscosity of the fluid
ν = kinematic viscosity of the fluid
Significance Reynolds Number:
Re < 2000: Laminar flow (smooth and orderly flow).
2000 < Re < 4000: Transitional flow (mix of laminar and turbulent flow).
Re > 4000: Turbulent flow (chaotic and irregular flow)