免费斯托克斯沉降计算器
使用斯托克斯定律计算球形颗粒在流体中的沉降速度。
Settling Velocity
0.00898943 m/s
Settling Velocity vs Particle Density
公式
## 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)** - *rho_p* = particle density - *rho_f* = fluid density - *r* = particle radius - *mu* = dynamic viscosity This applies when Re < 1 (creeping flow regime). Larger particles settle faster because velocity scales as r^2.
计算示例
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
常见问题
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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