1. What is Stokes Law?

Stokes Law describes the force of viscosity on a small sphere moving slowly through a fluid. It provides the relationship between the drag force and the settling velocity of spherical particles in a fluid medium.

2. How Does the Calculator Work?

The calculator uses the Stokes Law formula:

Where:

• \( V_s \) — Settling velocity (m/s)
• \( F_D \) — Drag force (N)
• \( \mu \) — Dynamic viscosity (Pa·s)
• \( D \) — Diameter of the particle (m)
• \( \pi \) — Mathematical constant pi (≈3.1416)

Explanation: The formula calculates the terminal velocity at which the gravitational force on a spherical particle is balanced by the drag force and buoyancy.

3. Importance of Settling Velocity Calculation

Details: Settling velocity calculations are crucial in various fields including sediment transport, wastewater treatment, particle separation processes, and environmental engineering for predicting how particles settle in fluids.

4. Using the Calculator

Tips: Enter drag force in Newtons, dynamic viscosity in Pascal-seconds, and diameter in meters. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What are the assumptions of Stokes Law?
A: Stokes Law assumes spherical particles, laminar flow (low Reynolds number), uniform particle size, and that particles are far from container walls.

Q2: What is the typical range of applicability for Stokes Law?
A: Stokes Law is valid for Reynolds numbers less than 0.1, which corresponds to very small particles settling slowly in viscous fluids.

Q3: How does temperature affect settling velocity?
A: Temperature affects fluid viscosity - higher temperatures generally decrease viscosity, which increases settling velocity according to Stokes Law.

Q4: Can Stokes Law be used for non-spherical particles?
A: For non-spherical particles, shape factors and corrections must be applied as the original Stokes Law is derived for perfect spheres.

Q5: What are some practical applications of settling velocity calculations?
A: Applications include water treatment plants, sedimentation tanks, air pollution control, pharmaceutical manufacturing, and geological sediment analysis.