Laminar flow of a Newtonian fluid breaks down and transitions when the Reynolds number exceeds___________________?
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Answer: B. 2100
Explanation
Laminar flow remains stable until inertial forces overcome stabilizing viscous damping mechanisms completely. Experiments demonstrate that smooth pipe flow destabilizes around a Reynolds number of 2100. Exceeding this critical threshold triggers rapid fluctuations and transition into turbulent flow regimes. The Reynolds number represents the dimensionless ratio of fluid inertial forces to viscous forces. Osborne Reynolds famously demonstrated this flow transition using dye injections in glass pipes. Flow below the critical limit dampens perturbations, maintaining smooth parallel fluid streamlines.
Engineers design pipeline systems for viscous liquids to operate below this threshold safely. Maintaining laminar flow prevents excessive pressure drops and turbulence-induced erosion in pipes. Blood flow in smaller human capillaries typically remains well within this stable laminar regime. Option A represents a fully turbulent threshold value well above the initial transition zone. Option C is too low and underestimates the actual onset of pipe flow disturbances. Option D describes a transitional zone value rather than the standard accepted critical number.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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