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 sedimentology, chemical engineering, and aerosol science.

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 with viscous drag force to determine terminal velocity.

3. Importance of Settling Velocity

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

4. Using the Calculator

Tips: Enter all values in SI units. Particle radius should be in meters (convert from microns by multiplying by 10^-6). All values must be positive.

5. Frequently Asked Questions (FAQ)

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

Q2: When is Stokes Law not applicable?
A: For large particles, high velocities (turbulent flow), non-spherical particles, or in non-Newtonian fluids.

Q3: How to convert dynamic viscosity from cP to Pa·s?
A: 1 cP = 0.001 Pa·s. Water at 20°C has μ ≈ 0.001 Pa·s.

Q4: What's the maximum particle size for Stokes Law?
A: Typically <50μm in water, but depends on density difference and viscosity.

Q5: How does temperature affect settling velocity?
A: Higher temperature reduces viscosity (μ), increasing settling velocity for the same particle.