Calculateur de Sédimentation de Stokes Gratuit
Calculez la vitesse de sédimentation d'une particule avec la loi de Stokes. Déterminez le temps de décantation.
Settling Velocity
0.00898943 m/s
Settling Velocity vs Particle Density
Formule
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.
Exemple Résolu
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
Questions Fréquentes
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.
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