Home
Back
Stokes' Law for Low Reynolds Number:
| From: | To: |
The drag coefficient (C_d) is a dimensionless quantity that describes the drag or resistance of an object in a fluid environment. The Reynolds number (Re) is a dimensionless quantity that predicts flow patterns in different fluid flow situations, representing the ratio of inertial forces to viscous forces.
The calculator uses Stokes' law for low Reynolds numbers:
Where:
Explanation: Stokes' law provides the drag coefficient for a sphere at low Reynolds numbers (typically Re < 1), where viscous forces dominate over inertial forces.
Details: Accurate drag coefficient calculation is crucial for predicting fluid resistance on objects, designing aerodynamic and hydrodynamic systems, and understanding particle sedimentation in various engineering applications.
Tips: Enter the Reynolds number (must be greater than 0). The calculator is valid for low Reynolds numbers where Stokes' law applies (typically Re < 1).
Q1: What is the range of validity for Stokes' law?
A: Stokes' law is valid for low Reynolds numbers, typically Re < 1, where flow is laminar and viscous forces dominate.
Q2: How does drag coefficient change with Reynolds number?
A: At low Re, C_d decreases as 24/Re. At higher Re, the relationship becomes more complex and empirical correlations are needed.
Q3: What factors affect the drag coefficient?
A: Shape of the object, surface roughness, fluid properties, and flow conditions all influence the drag coefficient.
Q4: When is Stokes' law not applicable?
A: For high Reynolds numbers, non-spherical objects, turbulent flow conditions, or when other forces (such as buoyancy or electrostatic) are significant.
Q5: What are typical drag coefficient values?
A: For spheres at low Re, C_d can be very high (hundreds to thousands). For streamlined objects at high Re, C_d can be as low as 0.04-0.1.