Engineering Sciences
Mechanical Engineering
1883
IntermediateReynolds Number
Ratio of inertial to viscous forces—predicts laminar vs turbulent flow.
By Osborne Reynolds
Engineering Sciences
Reynolds Number
1883 · Osborne Reynolds
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Why it matters: Dimensionless number enabling scale modeling of fluid systems.
Discoverers: Osborne Reynolds (1883)
What does it mean?
Ratio of inertial to viscous forces—predicts laminar vs turbulent flow.
Why should I care?
Dimensionless number enabling scale modeling of fluid systems.
Equation Compass
North — Prerequisites
West — History
East — Applications
South — Derivations
Variables & Units
| Symbol | Name | Unit | Meaning |
|---|---|---|---|
| Reynolds number | — | Dimensionless | |
| Density | — | kg/m³ | |
| Velocity | — | m/s | |
| Length scale | m | Characteristic length | |
| Viscosity | — | Pa·s |
Worked Example
Pipe flow: Re < 2300 laminar, Re > 4000 turbulent.
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Ratio of inertial to viscous forces—predicts laminar vs turbulent flow.
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