Reynolds Number: Water at 3 m/s in a 3 cm Pipe
Water flowing at 3 m/s through a 3 cm diameter pipe gives Re = 90000, well into the turbulent regime.
How to use this tool
- Enter fluid density ρ, flow velocity v, characteristic length l and dynamic viscosity μ in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your reynolds number re and the full breakdown beneath it.
Use this preset to calculate the Reynolds number for fast-moving water in a small pipe, confirming highly turbulent conditions.
Frequently asked questions
- What fluid properties should I use for water and air?
- Water at 20°C: ρ = 998 kg/m³, μ = 0.001002 Pa·s. Air at 20°C: ρ = 1.204 kg/m³, μ = 1.81×10⁻⁵ Pa·s.
- What is the characteristic length for a pipe?
- For flow inside a pipe, use the internal diameter as the characteristic length. For flow over a flat plate, use the plate length.