Stirred-Tank Reynolds Number
Stirred-Tank Reynolds Number
The impeller Reynolds number tells whether mixing in a stirred tank is laminar or turbulent, setting the power number and blend time.
The impeller Reynolds number is Re = ρ·N·D²/μ. where ρ is density, N the rotational speed, D the impeller diameter and μ the viscosity.
Inputs
rho := 1000 kg/m^3=1000 kg/m^3
N := 5 Hz=5 Hz
D := 0.3 m=300 mm
mu := 0.001 Pa·s=1e-03 kg/m/s
Form the impeller Reynolds number.
Re := rho·N·D^2/mu=450000
Results
Above about 10⁴ the tank is fully turbulent and well mixed; below ~10 it is laminar. The value selects the correct power-number correlation.
Assumptions & limitations
- Newtonian fluid.
- Speed in revolutions per second.
- Standard impeller geometry.