Flat-Plate Reynolds Number
Flat-Plate Reynolds Number
For external flow the Reynolds number uses the distance along the surface, deciding where the boundary layer turns turbulent.
The Reynolds number is Re = ρ·v·L/μ. where ρ is density, v the velocity, L the plate length and μ the viscosity.
Inputs
rho := 1.225 kg/m^3=1.23 kg/m^3
v := 20 m/s=20 m/s
L := 2 m=2 m
mu := 1.8e-5 Pa·s=1.8e-05 kg/m/s
Form the Reynolds number on plate length.
Re := rho·v·L/mu=2.72e+06
Results
Transition to turbulence on a flat plate occurs near Re ≈ 5×10⁵. The value here is well past it, so most of the plate has a turbulent boundary layer.
Assumptions & limitations
- Length-based Reynolds number.
- Newtonian fluid.
- Smooth flat plate.