Calcolatore Legge di Stokes
Calcola la velocità di sedimentazione di una particella sferica in un fluido viscoso.
Settling Velocity
0.00898943 m/s
Settling Velocity vs Particle Density
Formula
Stokes Settling (Low Reynolds Number)
Very small particles settle through a fluid at a terminal velocity governed by Stokes' law.
Formula
v_s = 2 (rho_p - rho_f) g r^2 / (9 mu)
This applies when Re < 1 (creeping flow regime). Larger particles settle faster because velocity scales as r^2.
Esempio Risolto
Sand grain (r = 50 um, rho = 2650 kg/m3) in water.
- 01v_s = 2 * (2650 - 1000) * 9.807 * (5e-5)^2 / (9 * 0.001)
- 02delta_rho = 1650
- 03r^2 = 2.5e-9
- 04v_s = 2 * 1650 * 9.807 * 2.5e-9 / 0.009
- 05v_s = 8.09e-5 / 0.009 = 0.00899 m/s
Domande Frequenti
When does Stokes law fail?
When the particle Reynolds number exceeds about 1, inertial effects become important and the drag coefficient no longer scales linearly with velocity.
How does this apply to sedimentation?
Stokes settling governs sedimentation in lakes, blood cell separation in centrifuges, and paint settling in cans.
What about non-spherical particles?
An equivalent-sphere correction factor is applied. Flatter or more irregular particles settle slower than spheres of the same mass.
Impara