| (1) | {\rm Re} = \frac{v \, L}{\nu} = \frac{\rho \, v \, L}{\mu} |
Dimension = dimensionless
The physical meaning of Reynolds number is the ratio of intertial forces and viscous forces:
| (2) | {\rm Re} = \frac{{\rm Inertial} \ {\rm forces}}{{\rm Viscous} \ {\rm forces}} |