Engineering
Advanced

Reynolds Number

Predicts laminar vs turbulent flow.

Formula

Re=ρvLμRe = \frac{\rho v L}{\mu}

Variables

\rhoDensity
vVelocity
LLength
\muViscosity

Example

Below Re ≈ 2300 pipe flow is smooth (laminar); above it turns turbulent.

Did You Know?

The Reynolds number predicts whether flow is smooth or turbulent — vital for pipes, wings, and blood vessels.

fluidsreynoldsflow