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Stokes' Law Equation:
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Stokes' law provides the drag coefficient for a sphere at low Reynolds numbers (typically Re < 0.1). This equation describes the relationship between drag coefficient and Reynolds number for creeping flow conditions where viscous forces dominate.
The calculator uses Stokes' law equation:
Where:
Explanation: This inverse relationship shows that as Reynolds number increases, the drag coefficient decreases, which is characteristic of laminar flow conditions at low Reynolds numbers.
Details: Calculating drag coefficient is essential for understanding fluid resistance on spherical objects, designing particle separation systems, analyzing sedimentation rates, and studying fluid dynamics in various engineering applications.
Tips: Enter the Reynolds number (must be greater than 0). This calculator is valid for low Reynolds numbers (typically Re < 0.1) where Stokes' law applies.
Q1: What is the range of validity for Stokes' law?
A: Stokes' law is valid for very low Reynolds numbers, typically Re < 0.1, where flow is laminar and viscous forces dominate.
Q2: Why does drag coefficient decrease with increasing Reynolds number?
A: At low Reynolds numbers, the drag force is primarily due to viscous effects. As Reynolds number increases, the relative importance of viscous forces decreases compared to inertial forces.
Q3: Can this equation be used for non-spherical objects?
A: No, Stokes' law in this form is specifically derived for spherical objects. Different shapes have different drag coefficient relationships.
Q4: What are typical applications of Stokes' law?
A: Applications include calculating settling velocities of particles, designing filtration systems, analyzing aerosol behavior, and studying microscopic fluid dynamics.
Q5: How does temperature affect the drag coefficient calculation?
A: Temperature affects fluid viscosity, which in turn affects Reynolds number. The relationship through Stokes' law remains valid, but the input parameters may change with temperature.