Home
Back
Stokes' Law Approximation:
| From: | To: |
The drag coefficient (C_d) is a dimensionless quantity that describes an object's resistance to fluid flow. Stokes' law provides an approximation for the drag coefficient of a sphere at low Reynolds numbers, where viscous forces dominate.
The calculator uses Stokes' law approximation:
Where:
Explanation: This equation provides a good approximation for the drag coefficient of spherical objects at low Reynolds numbers (typically Re < 0.1), where flow is laminar and viscous effects dominate.
Details: Accurate drag coefficient estimation is crucial for predicting fluid resistance on objects, designing aerodynamic structures, calculating terminal velocities, and analyzing particle motion in fluids.
Tips: Enter the Reynolds number (must be > 0). The calculator is valid for low Reynolds numbers where Stokes' law approximation applies.
Q1: What is the range of validity for Stokes' law?
A: Stokes' law approximation is typically valid for Reynolds numbers less than 0.1, where flow is laminar and viscous forces dominate.
Q2: Why is the drag coefficient dimensionless?
A: The drag coefficient is dimensionless because it represents the ratio of drag force to the product of dynamic pressure and reference area.
Q3: How does Reynolds number affect drag coefficient?
A: At low Reynolds numbers, drag coefficient decreases with increasing Reynolds number. At higher Reynolds numbers, the relationship becomes more complex and depends on flow regime.
Q4: Can this be used for non-spherical objects?
A: No, this specific formula is derived for spherical objects. Non-spherical objects have different drag coefficient relationships.
Q5: What are typical drag coefficient values?
A: For spheres at low Reynolds numbers, drag coefficients can range from 240 (Re=0.1) to much higher values at extremely low Reynolds numbers.