Stoke’s law remains applicable when the particle Reynolds number NRe, p falls below_________________?
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Answer: A. 2
Explanation
Stokes law derivation assumes inertial forces are completely negligible compared to viscous drag forces surrounding the sphere. Mathematical rigor dictates that this creeping flow approximation remains valid only when the particle Reynolds number stays very small. Empirical and theoretical validations confirm that inertial effects become significant once the particle Reynolds number exceeds two. The particle Reynolds number is calculated using particle diameter, fluid density, relative velocity, and dynamic fluid viscosity. Creeping flow represents a low Reynolds number hydrodynamic regime dominated entirely by linear viscous shear forces. George Gabriel Stokes formulated this classic drag law for spheres moving slowly through viscous fluid media.
A Reynolds number of 100 falls well within the laminar boundary separation regime where inertial forces dominate significantly. A Reynolds number of 2100 marks the typical transition threshold from laminar to turbulent flow inside circular pipes. A Reynolds number of 700 represents fully developed unsteady vortex shedding flow regimes far beyond creeping flow limits.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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