The Reynolds number threshold most commonly associated with transition to turbulence is approximately:

The Reynolds number threshold most commonly associated with transition to turbulence is approximately:

• A. 1000
• B. 1500
• C. 2000
• D. 2500

Answer: (C)

Reynolds number compares inertial forces to viscous forces in a fluid. When viscosity dominates (low Re), the flow stays smooth and laminar. As Re grows, inertial effects become stronger and disturbances can amplify, leading to turbulence. In straight pipe flow, the onset of transition from laminar to turbulent is most commonly associated with Re around two thousand, though the exact transition range can vary and often spans roughly from 1900 to 2300 depending on conditions. Among the given values, about two thousand best matches this widely cited threshold, which is why it’s the correct choice. Values much lower tend to remain laminar, and while slightly higher numbers like 2500 can be within the transitional range, they are not the standard benchmark as clearly as 2000 is.

Reynolds number compares inertial forces to viscous forces in a fluid. When viscosity dominates (low Re), the flow stays smooth and laminar. As Re grows, inertial effects become stronger and disturbances can amplify, leading to turbulence. In straight pipe flow, the onset of transition from laminar to turbulent is most commonly associated with Re around two thousand, though the exact transition range can vary and often spans roughly from 1900 to 2300 depending on conditions. Among the given values, about two thousand best matches this widely cited threshold, which is why it’s the correct choice. Values much lower tend to remain laminar, and while slightly higher numbers like 2500 can be within the transitional range, they are not the standard benchmark as clearly as 2000 is.