How it is calculated
The limits 2300 and 4000 are a convention. Roughness and how the flow enters can move the changeover.
Re = ρ × v × D / μ
Where the numbers come from
- Density — unit in the field: kg/m³
- Speed — unit in the field: m/s
- Diameter — unit in the field: m
- Viscosity — unit in the field: Pa·s
Example
Water at 1000 kg/m³, a speed of 1 m/s, a diameter of 0,05 m, and a viscosity of 0,001 Pa·s give Re = 50 000.
Questions
Kinematic viscosity instead of dynamic?
Divide dynamic viscosity by density, or take density out of the numerator and put ν in the denominator yourself: Re = vD/ν.
The pipe is not round?
Then you need the hydraulic diameter, which this screen does not calculate.
Water at 20 °C?
Dynamic viscosity is about 0,001 Pa·s. More exactly, it depends on the temperature.