1. What is Stokes Law?

Stokes Law describes the force of viscosity acting on spherical objects with very small Reynolds numbers in a viscous fluid. It is fundamental in fluid dynamics for calculating drag force on small particles moving through fluids.

2. How Does the Calculator Work?

The calculator uses the Stokes Law formula:

Where:

• \( F_D \) — Drag Force (N)
• \( \pi \) — Archimedes' constant (≈3.14159)
• \( \mu \) — Dynamic Viscosity (Pa·s)
• \( V_s \) — Settling Velocity (m/s)
• \( D \) — Diameter (m)

Explanation: The equation calculates the drag force experienced by a spherical particle moving through a viscous fluid at low Reynolds numbers.

3. Importance of Drag Force Calculation

Details: Accurate drag force calculation is crucial for understanding particle sedimentation, fluid flow analysis, designing separation processes, and studying particle dynamics in various engineering and scientific applications.

4. Using the Calculator

Tips: Enter dynamic viscosity in Pa·s, settling velocity in m/s, and diameter in meters. 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 applies only to spherical particles in laminar flow conditions with Reynolds numbers less than 0.1. It assumes the fluid is Newtonian and the particle is far from boundaries.

Q2: When is Stokes Law applicable?
A: Stokes Law is applicable for small particles moving slowly through viscous fluids, typically in sedimentation, centrifugation, and aerosol particle motion studies.

Q3: What is the significance of Reynolds number in Stokes Law?
A: Reynolds number indicates the flow regime. Stokes Law is valid only for very low Reynolds numbers (Re < 0.1) where viscous forces dominate over inertial forces.

Q4: Can Stokes Law be used for non-spherical particles?
A: No, Stokes Law is specifically derived for spherical particles. For non-spherical particles, shape factors and correction coefficients must be applied.

Q5: What are typical applications of Stokes Law?
A: Applications include calculating settling rates of particles in liquids, designing sedimentation tanks, analyzing blood cell movement, and studying atmospheric particle behavior.