Reynolds Number (Advanced) Calculator
Calculate the Reynolds number for flow through a pipe or over a surface: Re = rho * v * L / mu, with laminar/turbulent classification.
Reynolds Number
100,000.00
Reynolds Number vs Fluid Density
Formula
## Reynolds Number The Reynolds number predicts whether flow will be laminar (smooth) or turbulent (chaotic). ### Formula **Re = rho v L / mu** - *rho* = fluid density - *v* = flow velocity - *L* = characteristic length (pipe diameter, plate length) - *mu* = dynamic viscosity For pipe flow: Re < 2300 is laminar, 2300-4000 is transitional, > 4000 is turbulent.
Esempio Risolto
Water (rho = 1000, mu = 0.001) at 2 m/s through a 5 cm pipe.
- 01Re = rho v L / mu
- 02Re = 1000 * 2 * 0.05 / 0.001
- 03Re = 100 / 0.001 = 100 000
- 04This is well into the turbulent regime.
Domande Frequenti
What is the physical meaning of the Reynolds number?
It represents the ratio of inertial forces to viscous forces. High Re means inertia dominates (turbulent); low Re means viscosity dominates (laminar).
Why does the transition occur around Re = 2300?
This is an empirical observation for smooth pipe flow. Small disturbances are damped by viscosity at low Re but amplified at high Re.
Does the Reynolds number apply to gases?
Yes. Gases have lower density but also lower viscosity, so Re can still be high for fast flows.
Impara