1. What is Stokes Law?

Stokes Law describes the force of viscosity on a sphere moving through a viscous fluid at low Reynolds numbers. It provides a relationship between the drag force on a spherical particle and its diameter, settling velocity, and fluid viscosity.

2. How Does the Calculator Work?

The calculator uses the Stokes Law formula:

Where:

• \( D_S \) — Diameter of spherical particle (m)
• \( F_D \) — Drag force (N)
• \( \pi \) — Archimedes' constant (≈3.1416)
• \( V_s \) — Settling velocity (m/s)
• \( \mu \) — Dynamic viscosity (Pa·s)

Explanation: The formula calculates the diameter of a spherical particle based on the drag force it experiences when moving through a viscous fluid at its terminal settling velocity.

3. Importance of Particle Diameter Calculation

Details: Calculating particle diameter using Stokes Law is crucial in various fields including fluid mechanics, sedimentation analysis, aerosol science, and industrial processes involving particle separation and classification.

4. Using the Calculator

Tips: Enter drag force in newtons (N), settling velocity in meters per second (m/s), and dynamic viscosity in pascal-seconds (Pa·s). All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What are the limitations of Stokes Law?
A: Stokes Law is valid only for small spherical particles at low Reynolds numbers (Re < 0.1) in laminar flow conditions.

Q2: Can this formula be used for non-spherical particles?
A: No, Stokes Law specifically applies to spherical particles. For non-spherical particles, shape factors and other corrections are needed.

Q3: What is the typical range of particle sizes where Stokes Law applies?
A: Stokes Law typically applies to particles ranging from 1 micrometer to 100 micrometers in diameter, depending on fluid properties.

Q4: How does temperature affect the calculation?
A: Temperature affects dynamic viscosity significantly. Ensure viscosity values correspond to the actual temperature conditions of your application.

Q5: What units should I use for accurate results?
A: Use consistent SI units: newtons for force, meters per second for velocity, and pascal-seconds for viscosity to get diameter in meters.