1. What is Stokes Law?

Stokes Law describes the settling velocity of small spherical particles in a fluid medium. It's fundamental in fields like sedimentation, centrifugation, and particle size analysis.

2. How Does the Calculator Work?

The calculator uses the Stokes Law equation:

Where:

• \( v \) — Settling velocity (m/s)
• \( \rho_p \) — Particle density (kg/m³)
• \( \rho_f \) — Fluid density (kg/m³)
• \( \mu \) — Dynamic viscosity (Pa·s)
• \( g \) — Gravitational acceleration (9.81 m/s²)
• \( r \) — Particle radius (m)

Explanation: The equation balances gravitational force, buoyant force, and drag force to determine terminal settling velocity.

3. Importance of Settling Velocity

Details: Settling velocity calculations are crucial for designing sedimentation tanks, analyzing airborne particles, and understanding geological deposition processes.

4. Using the Calculator

Tips: Enter all values in SI units. Ensure particle radius is in meters (not micrometers). All density and viscosity values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What are the assumptions of Stokes Law?
A: Assumes spherical particles, laminar flow (Re < 1), no particle-particle interactions, and constant temperature.

Q2: What is the Reynolds number limitation?
A: Stokes Law is valid for Reynolds numbers below 1 (very small particles in viscous fluids).

Q3: How does temperature affect the calculation?
A: Temperature affects fluid viscosity (μ). Use viscosity values appropriate for your temperature.

Q4: Can this be used for non-spherical particles?
A: No, Stokes Law is strictly for spherical particles. For non-spherical particles, shape factors must be considered.

Q5: What if my particles are too large?
A: For larger particles where Re > 1, more complex equations (like Newton's Law) are needed.